Post by thread:Transformerless PSU

No exact or substring matches. trying for part
PICList Thread
'Transformerless PSU for PIC'
1999\11\30@045759 by Jinx

part 0 685 bytes The circuit counts mains cycles and supplies a small motor with 9V for about 1/2 second (dumped from the 3300u), adjustable timing / transistor drive for this from a 4001 one-shot. Functionally it works OK, what I'd like to have rendered efficient and safe is the 250VAC to 9V/5V part, correcting especially any stresses that anyone can see in the components used. I can't detect any heating and voltages seem to be stable. It's the type of transformerless circuit I build once in a blue moon and I haven't a good reference for it, basically modifying the first one made some time ago. Any suggestions ? Jinx Attachment converted: wonderland:mainspsu.gif (GIFf/JVWR) (000107EF)

1999\11\30@070319 by paulb

Jinx wrote: > Any suggestions ? Looks OK by and large. Not entirely sure what's the point of having the subsidiary 9V rail capacitor larger than the main reservoir cap, the other way round would seem more intuitive but maybe I'm wrong. Obviously you will have a number of decoupling capacitors across the PIC 5V rail *as well as* the Zener. -- Cheers, Paul B.

1999\11\30@105922 by Wagner Lipnharski

Hi Jinx, Due the need for lowest possible current on this system and the half wave rectifier, your 9V zener could transfer a high ripple to the final 5V zener. I wonder if the ripple could not reach the limits of 5V already. To avoid this possible problem, I would increase the system filtering, but to do that you need to increase the power drain from the source, what would need a bigger input cap and lower impedances in general, or, increase the 9V zener to a little higher voltage one, as 12V for example. The use of two zeners is a required safety procedure, since if the first zener blows up (open), your final circuit still protected by the second zener. I used a double configuration like that for a power meter with 0-1mA output, the Vdc is 12V and the primary zener is 33V. You would want to use a HSF (low ESR) capacitor at the 5V PIC input, with a couple of 0.1µF. The input cap (0.22µF) have different charge current for each senoid polarity. This is caused by your 9V zener that offers a 9V drop in one side of the senoid, while only 0.6V at the other senoid side. Remember that even with a nice current consume at the load, it is not the same as the full direct current flow through the zener. I used a 1N4007 diode in series with the zener, with a resistor in parallel to this diode. This resistor value is to balance both senoid polarity current over the cap. Without much calculation, I guess the primary cap current is around 9mA, so a 820 Ohms resistor should generate a Vdrop enough to balance when the senoid is negative at the hot wire. You need to test it in the bench. If you don't balance it, the cap will charge more than discharge, reducing the efficiency. | | ,---' A 12Vdc Zener | o---. | | 1N | R 820 Ohms 4007 _V_ R | | o---' | |

1999\11\30@163310 by Dwayne Reid

> Looks OK by and large. Not entirely sure what's the point of having >the subsidiary 9V rail capacitor larger than the main reservoir cap, the >other way round would seem more intuitive but maybe I'm wrong. > Actually - make sense to me - you want the PIC to power up faster than 40 mSec or you are likely to have weird reset problems. I use something very similar, except adapted for 120 Vac 60 Hz. My inrush limiting resistor is either 150R 0.5W (with 1 uF input cap) or 2 - 150R 0.5W resistors in parallel with a 2u2 input cap. I also put a LED and series 150R resistor in parallel with the inrush limiting resistor as a power indicator. The importtant thing here is that the inrush resistor is much larger than you would normally expect, with the resistor being carbon composition instead of film. Getting back to the original circuit Jinx posted, I would change the 1n914 diode (at the line sample input on the PIC) to a 4v7 xener. It doesn't cost much more than the 1n914 and ensures that the PIC input doesn't see high voltage. This is especially important if the sample gies to input GP3 on an 8 pin pic. The only other thing I use on some furnace controllers is a reset derived from the 5V supply. I use a cheapie pnp transistor (2n4403) wired with E to 5V rail, B to 4v3 zener cathode, C to reset with a pulldown resistor to gnd and a 100n cap from reset to vcc (across C-E of the transistor). Value of the pulldown depends whether I'm using an 8 pin pic or larger - the 8 pin PICs have a built in pullup which requires a lower value of pulldown resistor than normal. The anode of the 4v3 zener goes directly to gnd - the transistor / zener combo replaces the 5v zener in the original circuit. This has the advantage of holding the PIC in reset until the zener is conducting - the 100n cap across the transistor stops small transients from resetting the pic. Shipped many thousands of those with NO failures. Hope these comments help. dwayne Dwayne Reid <spam_OUTdwaynerTakeThisOuTplanet.eon.net> Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 15 years of Engineering Innovation (1984 - 1999) * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Do NOT send unsolicited commercial email to this email address. My posting messages to Usenet neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email.

1999\11\30@185628 by Jinx

Thanks for all suggestions so far. Point I should have made about the placement of the two large caps is that the motor just needs a flick to turn a cam every 15 seconds, and there's just enough juice in the 3300u to do that. It's a tiny motor that takes 50mA.The 470u is the PSU reservoir. The 3300u is isolated from the PIC supply by the 2k2 so that when the motor drains the 3300u it doesn't take the PIC supply down as well. So far I haven't had any problems with resets but the addition of other cheap components to preclude this and others to protect the PIC from spikes or over-voltage is good practise and means hopefully I'll never see it again as well as having a happy customer. Jinx

'[PICLIST] Transformerless PSU'
2001\07\25@205039 by Alexandre Domingos F. Souza

Dear guys, I think it's a basic one, but maybe fits the list I designed a circuit with a PIC (12C508) that turns on and off a relay, controlled by an external source. The power to this circuit (around 120mA) is a small transformer. I'd like to build a transformerless PSU into this circuit. But EVERY scheme I found on the internet was unusable. I saw something on the Embeeded Control Handbook from Microchip, but it only goes to (if I'm not mistaken) 45 mA. Maybe someone can help me to develop (or at least learn to) a simple transformerless PSU that can give me 12vcc / 120 mA??? Thanks for any info! :o) ---8<---Corte aqui---8<---- Alexandre Souza .....taitoKILLspam@spam@terra.com.br http://planeta.terra.com.br/lazer/pinball/ ---8<---Corte aqui---8<---- -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestKILLspammitvma.mit.edu

2001\07\25@211345 by Spehro Pefhany

At 09:52 PM 7/25/01 -0300, you wrote: > Dear guys, > > I think it's a basic one, but maybe fits the list > > I designed a circuit with a PIC (12C508) that turns on and off a relay, controlled by an external source. The power to this circuit (around 120mA) is a small transformer. I'd like to build a transformerless PSU into this circuit. But EVERY scheme I found on the internet was unusable. I saw something on the Embeeded Control Handbook from Microchip, but it only goes to (if I'm not mistaken) 45 mA. Maybe someone can help me to develop (or at least learn to) a simple transformerless PSU that can give me 12vcc / 120 mA??? I'd suggest not doing it. This kind of power supply has marginal reliability in many cases, and transformers are not that expensive in volume. If you must, then go to as high a voltage DC relay as possible to reduce the current. 24V at least. Keep in mind that without isolation any input or output is a potential source of DEATH to the user at any time in the future, over the life of each unit that you make. A typical 24VDC 360mW relay draws only 15mA. If you don't know how to scale the one shown in the MChip data then all the more reason to steer clear... transformers not only are more reliable but they are usually very effective at filtering noise and transients out of your circuit. A (bad) example of these is the crappy China-made IR light switches that sell for about $7 US retail on special (including die cast and molded housing, two CSA/UL light sockets, PCB, relay and IR sensor, supposedly weatherproofed, several pots and with a 4-color printed carton. These things last about one season around here. Best regards, =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Spehro Pefhany --"it's the network..." "The Journey is the reward" .....speffKILLspam.....interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= -- http://www.piclist.com hint: To leave the PICList EraseMEpiclist-unsubscribe-requestspam_OUTTakeThisOuTmitvma.mit.edu

2001\07\25@222722 by Edson Brusque

Hello Alexandre and Spehro, Alex, you don't want to use a transformer because of it's costs or to save weight and/or space? If cost isn't your problem, I would suggest you to buy a transformerless suply for 24V and step-it-down to 5V with a swithed-regulator like LT1173. You can use an small transistor to switch the relay from the PIC output and use the output from the LT1173 to power a 5V circuit up to about 300mA. LT1173 isn't cheap at about US$3.40 in Brazil. Best regards, Brusque ----------------------------------- Edson Brusque Research and Development C.I.Tronics Lighting Designers Ltda (47) 323-2138 / (47) 9993-6453 Blumenau - SC - Brazil http://www.citronics.com.br ----------------------------------- -- http://www.piclist.com hint: To leave the PICList piclist-unsubscribe-requestspam_OUTmitvma.mit.edu

2001\07\25@225713 by Alexandre Domingos F. Souza

> Alex, you don't want to use a transformer because of it's costs or to >save weight and/or space? It's a matter of space. Note the circuit is completely isolated from the operator (optocoupler). > If cost isn't your problem, I would suggest you to buy a transformerless >suply for 24V and step-it-down to 5V with a swithed-regulator like LT1173. >You can use an small transistor to switch the relay from the PIC output and >use the output from the LT1173 to power a 5V circuit up to about 300mA. > LT1173 isn't cheap at about US$3.40 in Brazil. Nah, I need it to be as small and CHEAP as possible :o( Any sugestions? ;o) ---8<---Corte aqui---8<---- Alexandre Souza @spam@taitoKILLspamterra.com.br http://planeta.terra.com.br/lazer/pinball/ ---8<---Corte aqui---8<---- -- http://www.piclist.com hint: To leave the PICList KILLspampiclist-unsubscribe-requestKILLspammitvma.mit.edu

2001\07\25@231653 by Spehro Pefhany

At 11:59 PM 7/25/01 -0300, you wrote: > Nah, I need it to be as small and CHEAP as possible :o( Any sugestions? ;o) If you insist, you can scale the supplies by simply increasing the capacitance and beefing up the other parts. But first try to reduce the current your circuit requires as much as possible. The higher the series resistor you put in there, the more heat you get, but the more resistant to transients your circuit will be. To get 100mA from a 240V 50Hz supply, you'd need a couple of uF rated for across the line operation (preferably 630VDC rating or UL/CSA X type if you want it to be relatively trouble-free). That means a fairly large film capacitor. They are fairly cheaply available (polyester). A transformer is usually better unless your product is throw-away cheap and dirty. Best regards, =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Spehro Pefhany --"it's the network..." "The Journey is the reward" RemoveMEspeffTakeThisOuTinterlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= -- http://www.piclist.com hint: To leave the PICList spamBeGonepiclist-unsubscribe-requestspamBeGonemitvma.mit.edu

2001\07\25@233121 by Gennette, Bruce

If you are trying to save space you're on a loser here. The 600V+ rated capacitor required to give >100mA in a transformerless power supply is *MUCH* bigger than than a transformer. *AND* about twice the price. Bye. {Original Message removed}

2001\07\26@014830 by Chris Carr

Presumably you are using a relay with a low voltage coil. Why not ease the low voltage current requirements by using a relay with a high voltage AC coil. If my presumption is correct then you will probably reduce your current consumption on the 5 volt rail to 45mA or less. Use a small Triac or thyristor to switch the relay. Regards Chris Carr > {Original Message removed}

2001\07\26@051543 by Roman Black

Alexandre Domingos F. Souza wrote: > > I designed a circuit with a PIC (12C508) that turns on and off a >relay, controlled by an external source. The power to this circuit (around >120mA) is a small transformer. I'd like to build a transformerless PSU into >this circuit. But EVERY scheme I found on the internet was unusable. I saw >something on the Embeeded Control Handbook from Microchip, but it only goes >to (if I'm not mistaken) 45 mA. Maybe someone can help me to develop (or at >least learn to) a simple transformerless PSU that 120mA. Hi Alexandre! This can be done if you REALLY want to do it. The Mchip app note shows 45mA, and that is with a half-wave rectifier (two diodes). Just change to a proper rectifier bridge, this will double the current to 90mA. Then using a 30% larger value of the main Xc cap will give you 120mA. This web page has Traffic.PDF sent by Richard Ottosen which shows a larger current Xc supply with a full-wave bridge: http://centauri.ezy.net.au/~fastvid/tube4w.htm IMPORTANT! using a full wave rectifier will give lethal voltages at ALL points of your 24v circuit. You no longer have a reference ground! I know you said you were using an optocoupler but remember at all times this circuit is dangerous... Some handy points, you can get reliable relay operation at half the hold current usng the old RC trick, which gives it full current for pull-in but only half current under hold. Costs one resistor and one 470uF electro. Maybe this would get you down to 60mA circuit current. I have used this trick down to about 25% hold current. Remember the Xc supply ALWAYS runs full current, so if your 120mA relay is OFF, something else (large zener?) must be drawing the 120mA. Have a serious think about this. Xc supply is best for circuits that always draw the same current. :o) -Roman -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2001\07\26@055235 by Bob

If the relay is a simple single pole on/off type, and not too many amperes are going through it, you could replace it with a triac and a zero crossing triac optocoupler interface (as low as 5ma current draw). If the load is inductive, you will need to add the proper snubber circuit too. You could then use a VB409 (from ST microelectronics) which is rated at 70ma out of its 5vdc 5% regulated pin (which should be more than enough to drive the triac opto and the pic), but I think it can kick out a bit more out of the 12~15Vdc unregulated pin (something like 140ma for 10ms max). Like the X cap setup, this part does run your circuit at line potential. Unlike the Xcap setup, it don't care if your not drawing anything from it, but it may need a heatsink if your drawing more than 40~45ma. {Original Message removed}

2001\07\26@061525 by Vasile Surducan

I've done one, some time ago, see http://www.geocities.com/vsurducan/c520.htm at the bottom of the page, up to 150mA, but I don't recommend such power supplies for production devices ( maybe on 120V mains, only ) Note that in my design, the supply don't like to remain without load... Vasile On Thu, 26 Jul 2001, Roman Black wrote: {Quote hidden}> Alexandre Domingos F. Souza wrote: > > > > I designed a circuit with a PIC (12C508) that turns on and off a > >relay, controlled by an external source. The power to this circuit (around > >120mA) is a small transformer. I'd like to build a transformerless PSU into > >this circuit. But EVERY scheme I found on the internet was unusable. I saw > >something on the Embeeded Control Handbook from Microchip, but it only goes > >to (if I'm not mistaken) 45 mA. Maybe someone can help me to develop (or at > >least learn to) a simple transformerless PSU that 120mA. > > > Hi Alexandre! This can be done if you REALLY want > to do it. The Mchip app note shows 45mA, and that > is with a half-wave rectifier (two diodes). > > Just change to a proper rectifier bridge, this will > double the current to 90mA. Then using a 30% larger > value of the main Xc cap will give you 120mA. > This web page has Traffic.PDF sent by Richard Ottosen > which shows a larger current Xc supply with a > full-wave bridge: > http://centauri.ezy.net.au/~fastvid/tube4w.htm > > IMPORTANT! using a full wave rectifier will give > lethal voltages at ALL points of your 24v circuit. > You no longer have a reference ground! I know you > said you were using an optocoupler but remember at > all times this circuit is dangerous... > > Some handy points, you can get reliable relay > operation at half the hold current usng the old RC > trick, which gives it full current for pull-in > but only half current under hold. Costs one resistor > and one 470uF electro. Maybe this would get you > down to 60mA circuit current. I have used this trick > down to about 25% hold current. > > Remember the Xc supply ALWAYS runs full current, > so if your 120mA relay is OFF, something else > (large zener?) must be drawing the 120mA. Have a > serious think about this. Xc supply is best for > circuits that always draw the same current. > :o) > -Roman > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2001\07\26@064931 by Spehro Pefhany

At 12:10 PM 7/26/01 +0300, you wrote: >I've done one, some time ago, see >http://www.geocities.com/vsurducan/c520.htm >at the bottom of the page, up to 150mA, but I don't recommend such power >supplies for production devices ( maybe on 120V mains, only ) >Note that in my design, the supply don't like to remain without load... >Vasile If you use something like this (and I don't recommend it..) be sure to put a resistor in series with the capacitor to reduce current surge and in *parallel* with the capacitor .. because there is a good chance if it is unplugged near the peak line voltage the capacitor may hold as much as +/-300V charge .. that's enough energy in a 4.7uF cap to give someone a goodly shock, and they can get it quite easily without opening the case, if you see that? Best regards, =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Spehro Pefhany --"it's the network..." "The Journey is the reward" TakeThisOuTspeffEraseMEspam_OUTinterlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2001\07\26@071458 by Vasile Surducan

Yapp, thank's for the point, I knew it ( it's more than 300V, it's 316V usual and much more on spikes or mains failure ) but this one was intend to work plugin forever , and exactly like this is working continuously from about two years...with same capacitor. But needs a VERY GOOD capacitor and I must admit, I had search something for it. (any cap or xcap like you named it, who make a delicate noise, almost imperceptible, will die soon ) About the current surge, you have right, there is a series resistor which seems is missing in the picture. Vasile On Thu, 26 Jul 2001, Spehro Pefhany wrote: {Quote hidden}> At 12:10 PM 7/26/01 +0300, you wrote: > >I've done one, some time ago, see > >http://www.geocities.com/vsurducan/c520.htm > >at the bottom of the page, up to 150mA, but I don't recommend such power > >supplies for production devices ( maybe on 120V mains, only ) > >Note that in my design, the supply don't like to remain without load... > >Vasile > > If you use something like this (and I don't recommend it..) be sure to > put a resistor in series with the capacitor to reduce current surge and > in *parallel* with the capacitor .. because there is a good chance > if it is unplugged near the peak line voltage the capacitor may hold as > much as +/-300V charge .. that's enough energy in a 4.7uF cap to give > someone a goodly shock, and they can get it quite easily without > opening the case, if you see that? > > Best regards, > > =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= > Spehro Pefhany --"it's the network..." "The Journey is the reward" > RemoveMEspeffTakeThisOuTinterlog.com Info for manufacturers: http://www.trexon.com > Embedded software/hardware/analog Info for designers: http://www.speff.com > Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com > =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2001\07\26@072342 by mike

On Wed, 25 Jul 2001 21:52:50 -0300, you wrote: > Dear guys, > > I think it's a basic one, but maybe fits the list > > I designed a circuit with a PIC (12C508) that turns on and off a relay, controlled by an external source. The power to this circuit (around 120mA) is a small transformer. I'd like to build a transformerless PSU into this circuit. But EVERY scheme I found on the internet was unusable. I saw something on the Embeeded Control Handbook from Microchip, but it only goes to (if I'm not mistaken) 45 mA. Maybe someone can help me to develop (or at least learn to) a simple transformerless PSU that can give me 12vcc / 120 mA??? > For that current, a transformer will be the cheapest, and probably not far off the smallest solution. Can you change the relay? - some types of relay are readily availalable with 48v coils, so you immediately reduce your current requirement by a factor of four, making a transformerless solution more practical. Another possibility is to use a mains-coil relay, and a small (TO92) triac, or MOC3020 opto-triac to drive it. The PIC can be run from a small transformerless 5V supply Of course if you REALLY wanted to do it as small as possible, and have a strong nerve, you could use the PIC to PWM or phase-control the relay current to get 12v avarage from the mains, using the relay's inductance to limit peak current, but make sure think very carefully about what would happen if the software crashed! -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2001\07\26@093203 by Roman Black

Vasile Surducan wrote: > > I've done one, some time ago, see > http://www.geocities.com/vsurducan/c520.htm > at the bottom of the page, up to 150mA, but I don't recommend such power > supplies for production devices ( maybe on 120V mains, only ) > Note that in my design, the supply don't like to remain without load... > Vasile Hi Vasile! Great web page! But that picture power.gif scares me a bit! The only thing limiting the voltage across C5 is the current drawn by the load!! Maybe you could put a 8v 1w or larger zener diode across it. Would improve safety a lot! :o) -Roman -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2001\07\26@094431 by Spehro Pefhany

At 11:32 PM 7/26/01 +1000, you wrote: >Hi Vasile! Great web page! But that picture power.gif >scares me a bit! The only thing limiting the voltage >across C5 is the current drawn by the load!! The regulator or C5 will break down before it gets to 50V, most likely. ;-) Best regards, =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Spehro Pefhany --"it's the network..." "The Journey is the reward" speffEraseME.....interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2001\07\26@095636 by Roman Black

Spehro Pefhany wrote: > > At 11:32 PM 7/26/01 +1000, you wrote: > > >Hi Vasile! Great web page! But that picture power.gif > >scares me a bit! The only thing limiting the voltage > >across C5 is the current drawn by the load!! > > The regulator or C5 will break down before it gets to 50V, > most likely. ;-) Ha ha! You could design TV sets! ;o) -Roman -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2001\07\26@135805 by Steven Bakaletz

Download the application note from MicroChip for a dimmer using the 12C508 www.microchip.com/Download/appnote/category/rdesigns/40171a.pdf Strip off everything but the triac part, and use that to drive a 120V AC relay. You don`t need the zero crossing just a high or low to the triac drive. Works I've used it. -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2001\07\27@063108 by Vasile Surducan

Like usual you have again right, but as I said already ( and test on about 100 hours with my measuring tools and more than 2 years just with my eyes...) it's no need any zenner on load or resistor across the capacitor if: - never plug on the supply without computed load connected ( and no other load ! ) - use a best quality polyester or PMP capacitor with nominal voltage 2 or 3 times greater than maximum voltage you may have (have big size ! ) I other condition I use a 5W 12V zenner as you've mentioned, but I don't like this sort of supplies (I've repaired many supplies like this, produced at Ganz-Hungary in some energetic equipment, here the capacitor was protected with a varistor who crashed frequently, also the protective zenner diode crashed ...), it's easy to develop a comutation supply up to 100W with only one power transistor, an a cheap UC344 or TL494, a little transformer, some fast diodes and some capacitors. You don't need to know only Faraday's low and some tricks about projecting a good pcb. Maybe in my next web page... Cheers, Vasile On Thu, 26 Jul 2001, Roman Black wrote: {Quote hidden}> Vasile Surducan wrote: > > > > I've done one, some time ago, see > > http://www.geocities.com/vsurducan/c520.htm > > at the bottom of the page, up to 150mA, but I don't recommend such power > > supplies for production devices ( maybe on 120V mains, only ) > > Note that in my design, the supply don't like to remain without load... > > Vasile > > > Hi Vasile! Great web page! But that picture power.gif > scares me a bit! The only thing limiting the voltage > across C5 is the current drawn by the load!! > Maybe you could put a 8v 1w or larger zener diode > across it. Would improve safety a lot! > :o) > -Roman > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

2001\07\27@063111 by Vasile Surducan

The regulator input never gets here more than 15V because I have a serious load on the unregulated section ( connected directly to the filtering capacitors ). Knowing this potential is a projecting rule for this kind of garbage supplys. Also you must know which is the whole variation domain for cos_fi on your local mains ( it's important to know if you have a more inductive or more capacitive loads connected on the same mains ) The capacitive reactance for pure resistive loads or for inductive loads is not the same (thinking from the capacitor life point of wiew ) and must be computed both for maximum voltage variation and supply cos_fi variation. Probably my last english phrases will be dificult to understood... Cheers, Vasile On Thu, 26 Jul 2001, Spehro Pefhany wrote: {Quote hidden}> At 11:32 PM 7/26/01 +1000, you wrote: > > >Hi Vasile! Great web page! But that picture power.gif > >scares me a bit! The only thing limiting the voltage > >across C5 is the current drawn by the load!! > > The regulator or C5 will break down before it gets to 50V, > most likely. ;-) > > Best regards, > > =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= > Spehro Pefhany --"it's the network..." "The Journey is the reward" > EraseMEspeffinterlog.com Info for manufacturers: http://www.trexon.com > Embedded software/hardware/analog Info for designers: http://www.speff.com > Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com > =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

2001\07\27@085324 by Ned Seith

Vasile, Your series capacitance voltage divider circuit has certainly received criticism. So I hope that I'm not kicking a dead horse. While a transformer would definitely be the safest approach for the typical hobbyist, I'm glad to see that there is someone who is willing to be more intimate with the electrons. The concept and configuration of your series capacitance voltage divider circuit is fine. I have designed industrial applications which have provided several amps of current at low voltages from 220 Vac and 277 Vac mains using a series capacitor. Industrial equipment and machines frequently use a series capacitor instead of a transformer for providing lower voltages. A few points: I would not add a resistor in series with the capacitor (C9) as this will vary the effective capacitance reactance which is providing the desirable voltage drop and will also dissipate heat. I would not add a resistor in parallel to the capacitor (C9) as this will vary the effective capacitance reactance which is providing the desirable voltage drop. This resistor would also dissipate heat. I would not be too concerned with the capacitor (C9) remaining charged as the approximate 6 mA current consumption from the voltage regulator will quickly discharge the capacitor. UL and TUV stipulate that the voltage potential on an unplugged power cord must diminish to 1/3 of the mains voltage within 10 seconds. So, If I wanted to increase the rate at which the capacitor discharges, I would place a resistor in parallel to (C5) on the low voltage side of the circuit. I would want a 1/4 amp fuse between the 220 Vac main and the series capacitor (C9). I would also want the series capacitor (C9) rated for 800 V to 1000 V. If the series capacitor (C9) is getting warm at all, then the voltage rating should be increased. I would want the diode rectifiers voltage rating increased to 800 V to 1000 V (1N4006, 1N4007) to assure that there is not any brief reverse conduction during the delay of the capacitors charge cycle. Otherwise, looks good to me. Just a few comments from an old engineer. Sincerely, Ned Seith Nedtronics 59 3rd Street Gilroy, CA 95020 (408) 842-0858 G O T G A R L I C ? GILROY GARLIC FESTIVAL 2001 ! >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> At 12:10 PM 7/26/01 +0300, you wrote: {Quote hidden}>I've done one, some time ago, see >http://www.geocities.com/vsurducan/c520.htm >at the bottom of the page, up to 150mA, but I don't recommend such power >supplies for production devices ( maybe on 120V mains, only ) >Note that in my design, the supply don't like to remain without load... >Vasile > >On Thu, 26 Jul 2001, Roman Black wrote: > > > Alexandre Domingos F. Souza wrote: > > > > > > I designed a circuit with a PIC (12C508) that turns on and off a > > >relay, controlled by an external source. The power to this circuit (around > > >120mA) is a small transformer. I'd like to build a transformerless PSU > into > > >this circuit. But EVERY scheme I found on the internet was unusable. I saw > > >something on the Embeeded Control Handbook from Microchip, but it only > goes > > >to (if I'm not mistaken) 45 mA. Maybe someone can help me to develop > (or at > > >least learn to) a simple transformerless PSU that 120mA. > > > > > > Hi Alexandre! This can be done if you REALLY want > > to do it. The Mchip app note shows 45mA, and that > > is with a half-wave rectifier (two diodes). > > > > Just change to a proper rectifier bridge, this will > > double the current to 90mA. Then using a 30% larger > > value of the main Xc cap will give you 120mA. > > This web page has Traffic.PDF sent by Richard Ottosen > > which shows a larger current Xc supply with a > > full-wave bridge: > > http://centauri.ezy.net.au/~fastvid/tube4w.htm > > > > IMPORTANT! using a full wave rectifier will give > > lethal voltages at ALL points of your 24v circuit. > > You no longer have a reference ground! I know you > > said you were using an optocoupler but remember at > > all times this circuit is dangerous... > > > > Some handy points, you can get reliable relay > > operation at half the hold current usng the old RC > > trick, which gives it full current for pull-in > > but only half current under hold. Costs one resistor > > and one 470uF electro. Maybe this would get you > > down to 60mA circuit current. I have used this trick > > down to about 25% hold current. > > > > Remember the Xc supply ALWAYS runs full current, > > so if your 120mA relay is OFF, something else > > (large zener?) must be drawing the 120mA. Have a > > serious think about this. Xc supply is best for > > circuits that always draw the same current. > > :o) > > -Roman > > > > -- > > http://www.piclist.com hint: PICList Posts must start with ONE topic: > > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > > > > >-- >http://www.piclist.com hint: PICList Posts must start with ONE topic: >[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

2001\07\27@091026 by Roman Black

Ned Seith wrote: {Quote hidden}> > Vasile, > > Your series capacitance voltage divider circuit has certainly received > criticism. > So I hope that I'm not kicking a dead horse. > While a transformer would definitely be the safest approach for the typical > hobbyist, I'm glad to see that there is someone who is willing to be more > intimate with the electrons. > The concept and configuration of your series capacitance voltage divider > circuit is fine. > I have designed industrial applications which have provided several amps of > current at low voltages from 220 Vac and 277 Vac mains using a series > capacitor. Industrial equipment and machines frequently use a series > capacitor instead of a transformer for providing lower voltages. > A few points: > I would not add a resistor in series with the capacitor (C9) as this will > vary the effective capacitance reactance which is providing the desirable > voltage drop and will also dissipate heat. > I would not add a resistor in parallel to the capacitor (C9) as this will > vary the effective capacitance reactance which is providing the desirable > voltage drop. This resistor would also dissipate heat. > I would not be too concerned with the capacitor (C9) remaining charged as > the approximate 6 mA current consumption from the voltage regulator will > quickly discharge the capacitor. UL and TUV stipulate that the voltage > potential on an unplugged power cord must diminish to 1/3 of the mains > voltage within 10 seconds. So, If I wanted to increase the rate at which > the capacitor discharges, I would place a resistor in parallel to (C5) on > the low voltage side of the circuit. > I would want a 1/4 amp fuse between the 220 Vac main and the series > capacitor (C9). > I would also want the series capacitor (C9) rated for 800 V to 1000 V. > If the series capacitor (C9) is getting warm at all, then the voltage > rating should be increased. > I would want the diode rectifiers voltage rating increased to 800 V to 1000 > V (1N4006, 1N4007) to assure that there is not any brief reverse conduction > during the delay of the capacitors charge cycle. > Otherwise, looks good to me. > Just a few comments from an old engineer. > > Sincerely, > Ned Seith Hi Ned, I find these type of supplies very interesting, and have been playing with them for many years. Since before they were legal. :o) I'm really interested in your "several amps" applications, can you give any more info? Size/cost of the capacitors? Or custom built capacitors? I've made some medium supplies with the 630v poly types, pref the blue milspec ones. They are still going good now after many years. Never been brave enough to sell one though, just for personal use in my workshop. Do you have any specific tricks for handling current under-loads or spike conditions? Regulation? Sorry to fire questions at you. :o) -Roman -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

2001\07\27@092025 by Eisermann, Phil [Ridg/CO]

> -----Original Message----- > From: Roman Black [sni[] > > I'm really interested in your "several amps" applications, > can you give any more info? and please share your wisdom with the list. I'm also interested in this sort of application. -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

2001\07\27@093726 by Spehro Pefhany

At 05:46 AM 7/27/01 -0700, you wrote: >I would not add a resistor in series with the capacitor (C9) as this will >vary the effective capacitance reactance which is providing the desirable >voltage drop and will also dissipate heat. It is the only thing limiting current when voltage transients appear at the input (as at turn-on). All production circuits will include this resistor. Consider the surge current rating on the metal film capacitor if nothing else... the current at switch-on is otherwise limited only by the impedance of the mains and the connections to the capacitor, which can blow the thin metalization right off the dielectric, creating holes and eventual failure ('self healing' notwithstanding). Needless to say, it also whacks the diodes with a surge, though diodes are fairly tough, I don't like to see the circuit dependent on external factors (such as whether the customer has plugged it into an extension cord or not) to be reliable. >I would not be too concerned with the capacitor (C9) remaining charged as >the approximate 6 mA current consumption from the voltage regulator will >quickly discharge the capacitor. UL and TUV stipulate that the voltage >potential on an unplugged power cord must diminish to 1/3 of the mains >voltage within 10 seconds. So, If I wanted to increase the rate at which >the capacitor discharges, I would place a resistor in parallel to (C5) on >the low voltage side of the circuit. This will do nothing- the capacitor is in series with the low voltage side when the plug is removed from the socket and the voltage will remain too long to meet any kind of safety standards without a parallel resistor. You won't see an approved design without it, or some equivalent. >I would want a 1/4 amp fuse between the 220 Vac main and the series >capacitor (C9). A flameproof fusible resistor can probably be used to avoid the need for that... it has to be a high surge current type anyway (not metal film, but MOF or wirewound). >I would also want the series capacitor (C9) rated for 800 V to 1000 V. Preferably with an AC rating > maximum line voltage. >If the series capacitor (C9) is getting warm at all, then the voltage >rating should be increased. Yes, a film cap should never get warm. Have you gotten your "several amperes" supplies inspected by any safety approval agencies? Are there any power factor specifications that cause problems? Best regards, =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Spehro Pefhany --"it's the network..." "The Journey is the reward" RemoveMEspeffEraseMEEraseMEinterlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

2001\07\27@112421 by Ned Seith

Roman, I had the good fortune, in the early 1990's, of consulting with Ralph Kerrigan, the Chief Capacitor Design Engineer with Sprague Electric due to the quantity of capacitors that I was ordering. I will share a few things that I learned from Mr. Kerrigan. At that time, the high voltage capacitors manufactured by Sprague were available with either a "foil" conductive material or with a "metalized film" conductive material. Mr. Kerrigan indicated that the "foil" conductive material had a superior reliability for handling "higher currents" while the "metalized film" conductive material had a superior reliability for "voltage transients". The "metalized film" also had a "self healing" characteristic allowing for recovery from minor transient voltage damage. At that time, the Sprague high voltage capacitors were also available with a "polyester" film dielectric material, a "polypropylene" film dielectric material or a "polycarbonate" film dielectric material. The "polypropylene" film was superior to the "polyester" film and cost 150% more than the "polyester" film.. The "polycarbonate" film was superior to the "polypropylene" film and cost 650% more than the "polyester" film. After weighing all the pros and cons, I decided to go with the "metalized film" conductive material with the "polypropylene" film dielectric material. This combination was available off the shelf in voltage ratings from 400V to 2000V in standard capacitance values. However, I had to special order because my specification of 1.68uF was not a standard value. I could have used an off the shelf 1uF and a 0.68uF combination, however, that would have doubled the cost and the physical space required. The body of these capacitors was approximately 1" in diameter and 3" in length. These capacitors had the typical oval geometry, typical white body and typical yellow outer wrap. In quantities of 10,000 the capacitors were $3.90. These capacitors were used to replace malfunctioning solid state controllers that provided 120 Vac to "Exit Lamps" from a 277 Vac main in all the international airports throughout the free world! Prior to this project, I didn't know that the typical international airport has 2,000 "Exit Lamps". The capacitors that you have are probably "foil" and "polyester" film which are fine for non critical applications. You should be able to purchase small quantities of "metalized" "polypropylene" film capacitors from a capacitor manufacturer's distributor and might even acquire "free" engineering samples! It should be noted that a 1,000 V "foil" and "polyester" film capacitor will provide a similar level of reliability as a 630 V "metalized" film and "polypropylene" film capacitor. This is why I emphasized raising the voltage ratings of the capacitors. The most important thing is that the voltage rating is more than adequate and that the capacitor is not generating heat. The capacitors surface temperature should never be allowed to reach 75ºC. The "Exit Lamp" capacitors while enclosed in the lamp fixtures experienced a maximum increase in surface temperature of 3ºC after 72 hours of continuous operation. I eventually upgraded the "Exit Lamp" design with SIDACs (SYDACs) that were manufactured by RCA and Motorola at that time. The SIDAC is a very interesting thyristor that has many useful applications. A simple but inaccurate description of the SIDAC would be that it is a two terminal TRIAC (DIAC) that must be activated by the application of a voltage that is greater than the typical 130 Vac main. Placing a SIDAC in series with a 120V lamp on a 120 Vac main will accomplish nothing. However, placing a 120V lamp in series with a SIDAC on a 277 Vac main will illuminate the lamp! One last bit of advice and hocus pocus . . . When ever dealing with high voltages, I sincerely think that it is best to be in a Nikola Tesla state of mind! Good luck with the killer volts! Sincerely, Ned Seith Nedtronics 59 3rd Street Gilroy, CA 95020 (408) 842-0858 G O T G A R L I C ? GILROY GARLIC FESTIVAL 2001 STARTS TODAY! At 11:10 PM 7/27/01 +1000, you wrote: {Quote hidden}>Ned Seith wrote: > > > > Vasile, > > > > Your series capacitance voltage divider circuit has certainly received > > criticism. > > So I hope that I'm not kicking a dead horse. > > While a transformer would definitely be the safest approach for the typical > > hobbyist, I'm glad to see that there is someone who is willing to be more > > intimate with the electrons. > > The concept and configuration of your series capacitance voltage divider > > circuit is fine. > > I have designed industrial applications which have provided several amps of > > current at low voltages from 220 Vac and 277 Vac mains using a series > > capacitor. Industrial equipment and machines frequently use a series > > capacitor instead of a transformer for providing lower voltages. > > A few points: > > I would not add a resistor in series with the capacitor (C9) as this will > > vary the effective capacitance reactance which is providing the desirable > > voltage drop and will also dissipate heat. > > I would not add a resistor in parallel to the capacitor (C9) as this will > > vary the effective capacitance reactance which is providing the desirable > > voltage drop. This resistor would also dissipate heat. > > I would not be too concerned with the capacitor (C9) remaining charged as > > the approximate 6 mA current consumption from the voltage regulator will > > quickly discharge the capacitor. UL and TUV stipulate that the voltage > > potential on an unplugged power cord must diminish to 1/3 of the mains > > voltage within 10 seconds. So, If I wanted to increase the rate at which > > the capacitor discharges, I would place a resistor in parallel to (C5) on > > the low voltage side of the circuit. > > I would want a 1/4 amp fuse between the 220 Vac main and the series > > capacitor (C9). > > I would also want the series capacitor (C9) rated for 800 V to 1000 V. > > If the series capacitor (C9) is getting warm at all, then the voltage > > rating should be increased. > > I would want the diode rectifiers voltage rating increased to 800 V to 1000 > > V (1N4006, 1N4007) to assure that there is not any brief reverse conduction > > during the delay of the capacitors charge cycle. > > Otherwise, looks good to me. > > Just a few comments from an old engineer. > > > > Sincerely, > > Ned Seith > > >Hi Ned, I find these type of supplies very interesting, >and have been playing with them for many years. Since >before they were legal. :o) > >I'm really interested in your "several amps" applications, >can you give any more info? Size/cost of the capacitors? >Or custom built capacitors? I've made some medium supplies >with the 630v poly types, pref the blue milspec ones. >They are still going good now after many years. Never >been brave enough to sell one though, just for personal >use in my workshop. > >Do you have any specific tricks for handling current >under-loads or spike conditions? Regulation? Sorry to fire >questions at you. :o) >-Roman > >-- >http://www.piclist.com hint: The list server can filter out subtopics >(like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

2001\07\27@115727 by Douglas Butler

> malfunctioning solid state controllers that provided 120 Vac to "Exit > Lamps" from a 277 Vac main in all the international airports > throughout the > free world! Prior to this project, I didn't know that the typical > international airport has 2,000 "Exit Lamps". What an odd voltage! I design stuff for seaports all over the world but I have never run into 277Vac. Is this some derivative of airplane wiring? Sherpa Doug -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

2001\07\27@120157 by Eisermann, Phil [Ridg/CO]

sounds like the phase voltage of a three-phase 480V Y-connected supply.... {Quote hidden}> -----Original Message----- > From: Douglas Butler [RemoveMEdbutlerspam_OUTKILLspamIMETRIX.COM] > Sent: Friday, July 27, 2001 11:50 AM > To: RemoveMEPICLISTTakeThisOuTspamMITVMA.MIT.EDU > Subject: Re: [EE]: Transformerless PSU > > > > malfunctioning solid state controllers that provided 120 > Vac to "Exit > > Lamps" from a 277 Vac main in all the international airports > > throughout the > > free world! Prior to this project, I didn't know that the typical > > international airport has 2,000 "Exit Lamps". > > What an odd voltage! I design stuff for seaports all over > the world but > I have never run into 277Vac. Is this some derivative of airplane > wiring? > > Sherpa Doug > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics > > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

2001\07\27@122928 by Spehro Pefhany

At 10:59 AM 7/27/01 -0500, you wrote: >sounds like the phase voltage of a three-phase 480V Y-connected supply.... Yup. 480/sqrt(3). I think mostly used in the USofA. Best regards, =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= Spehro Pefhany --"it's the network..." "The Journey is the reward" EraseMEspeffspamspamBeGoneinterlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com =-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

'[EE]: Transformerless PSU capacitors'
2001\07\27@130928 by Roman Black

Ned Seith wrote: {Quote hidden}> > Roman, > > I had the good fortune, in the early 1990's, of consulting with Ralph > Kerrigan, the Chief Capacitor Design Engineer with Sprague Electric due to > the quantity of capacitors that I was ordering. I will share a few things > that I learned from Mr. Kerrigan. At that time, the high voltage capacitors > manufactured by Sprague were available with either a "foil" conductive > material or with a "metalized film" conductive material. Mr. Kerrigan > indicated that the "foil" conductive material had a superior reliability > for handling "higher currents" while the "metalized film" conductive > material had a superior reliability for "voltage transients". The > "metalized film" also had a "self healing" characteristic allowing for > recovery from minor transient voltage damage. At that time, the Sprague > high voltage capacitors were also available with a "polyester" film > dielectric material, > a "polypropylene" film dielectric material or a "polycarbonate" film > dielectric material. The "polypropylene" film was superior to the > "polyester" film and cost 150% more than the "polyester" film.. The > "polycarbonate" film was superior to the "polypropylene" film and cost 650% > more than the "polyester" film. After weighing all the pros and cons, I > decided to go with the "metalized film" conductive material with the > "polypropylene" film dielectric material. This combination was available > off the shelf in voltage ratings from 400V to 2000V in standard capacitance > values. However, I had to special order because my specification of 1.68uF > was not a standard value. I could have used an off the shelf 1uF and a > 0.68uF combination, however, that would have doubled the cost and the > physical space required. The body of these capacitors was approximately 1" > in diameter and 3" in length. These capacitors had the typical oval > geometry, typical white body and typical yellow outer wrap. In quantities > of 10,000 the capacitors were $3.90. These capacitors were used to replace > malfunctioning solid state controllers that provided 120 Vac to "Exit > Lamps" from a 277 Vac main in all the international airports throughout the > free world! Prior to this project, I didn't know that the typical > international airport has 2,000 "Exit Lamps". > The capacitors that you have are probably "foil" and "polyester" film which > are fine for non critical applications. You should be able to purchase > small quantities of "metalized" "polypropylene" film capacitors from a > capacitor manufacturer's distributor and might even acquire "free" > engineering samples! > It should be noted that a 1,000 V "foil" and "polyester" film capacitor > will provide a similar level of reliability as a 630 V "metalized" film and > "polypropylene" film capacitor. This is why I emphasized raising the > voltage ratings of the capacitors. The most important thing is that the > voltage rating is more than adequate and that the capacitor is not > generating heat. The capacitors surface temperature should never be allowed > to reach 75ºC. The "Exit Lamp" capacitors while enclosed in the lamp > fixtures experienced a maximum increase in surface temperature of 3ºC > after 72 hours of continuous operation. > I eventually upgraded the "Exit Lamp" design with SIDACs (SYDACs) that were > manufactured by RCA and Motorola at that time. The SIDAC is a very > interesting thyristor that has many useful applications. A simple but > inaccurate description of the SIDAC would be that it is a two terminal > TRIAC (DIAC) that must be activated by the application of a voltage that is > greater than the typical 130 Vac main. Placing a SIDAC in series with a > 120V lamp on a 120 Vac main will accomplish nothing. However, placing a > 120V lamp in series with a SIDAC on a 277 Vac main will illuminate the lamp! > > One last bit of advice and hocus pocus . . . When ever dealing with high > voltages, I sincerely think that it is best to be in a Nikola Tesla state > of mind! > Good luck with the killer volts! Hi Ned, wow thanks for the info. I have saved your post for prosperity! :o) I'm an old hardware guy too, and have played with lots of caps, but generally i'm using the milspec polyester ones for size vs capacity. Let me say I really appreciate you sharing your experience here, like others I was a bit sceptical about your first post re not using the series resistor, as this is required by some certification standards, and series resistors always appeal to me as a TV repairer, i've seen what mains spike do to hardware! :o) I have a lot of polyprop caps, but generally don't use them as the 630v polyester are smaller and cheaper, but like I said before I don't sell HV cap products. I have seen some polyprops used in personal defence (electric discharge) products. And i've never seen one fail. Please keep sharing any wisdom you have on this matter, the whole Xc deal interests me a lot, I don't see why Xc should be any less respected than Xl but that always seems to be the case. In the future I see big improvements in caps but not much changing in inductors, and after being abused by my lecturer many years ago about my 45mA Xc supply, then seeing them become the modern standard some 15 years later, i'm now keeping an open mind as to where the future is headed. Capacitive transformers anyone?? -Roman -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

2001\07\27@140128 by Ned Seith

Spehro Pefhany, You are clearly well educated, however, I have an entirely different view of the situation. I do not consider resistors to be surge protectors. A 1,600 V inductive spike will have a DVDT that can not be suppressed by any RC circuit. If I was trying to implement surge protection I would employ an appropriate surge protector such as a Raychem over current surge protector. In my view, we are trying to get as much electrical current as possible from a high voltage source. As we are trying to "get" current, we don't want to "limit" the current whatsoever as that becomes counter productive, is inefficient and generates heat. In my view we want the impedance as low as possible. Voltage transients due to current in rushes are proportional to the resistance (impedance) of the circuit so that a higher resistance (impedance) will contribute to a higher transient voltage (I x R or I x Z). The majority of power line transients are due to "inductive" (not capacitive) voltage spikes caused by the collapsing electromagnetic fields of inductors which have experienced a removal of power. The power line's ability to kill equipment occurs when a motor or solenoid is deactivated at the moment of peak line voltage resulting in an inductive spike that is 7.07 times greater than the line voltage. The second most problematic source of voltage transients is from arching and ring oscillation in power switches and relay contacts which generates bursts of pulses with on times approaching RF frequencies. The switches and relay contacts also contribute to inductive voltage spikes of the inductive apparatus on their circuits. Turning off inductive equipment causes transients not turning inductive equipment on. As for power factor, the capacitive current of 150 mA in this application or a few amps in my applications is not of any significance to the utility companies local distribution transformer with a 10,000 amp capability. It should also be noted that if there was the introduction of a massive capacitive load to the power line that the line voltage would actually dip due to the current demand. The notion that capacitors are frail and can not withstand power line behavior is unsubstantiated. Capacitors have been used for decades as filters in equipment and directly connected across the power line. Utility companies employ capacitors for filtering and power factor compensation directly to the power lines. Selection of the proper composition of capacitor with a conservative voltage rating will assure reliability in conjunction with the power lines. For maximum reliability the capacitor should be rated for the electrical environment and not for just the working voltage. Excluding lightning strikes, when capacitors fail it is because the electrical environment exceeded the capacitor's rating. It should also be noted that a capacitor with a 2kV rating will absolutely not be harmed by the maximum inductive spike of 1,600 V produced on a 220 Vac power line. Of course lightning strikes require spark gap and/or MOV technology and there are no absolute assurances with lightning. I really honestly believe that Vasile should be commended for his circuit and encouraged. Sincerely, Ned Seith Nedtronics 59 3rd Street Gilroy, CA 95020 (408) 842-0858 G O T G A R L I C ? GILROY GARLIC FESTIVAL 2001 STARTS TODAY! At 09:39 AM 7/27/01 -0400, you wrote: {Quote hidden}>At 05:46 AM 7/27/01 -0700, you wrote: > > >I would not add a resistor in series with the capacitor (C9) as this will > >vary the effective capacitance reactance which is providing the desirable > >voltage drop and will also dissipate heat. > >It is the only thing limiting current when voltage transients appear at >the input (as at turn-on). All production circuits will include this >resistor. >Consider the surge current rating on the metal film capacitor if nothing >else... >the current at switch-on is otherwise limited only by the impedance of >the mains and the connections to the capacitor, which can blow the >thin metalization right off the dielectric, creating holes and eventual >failure ('self healing' notwithstanding). Needless to say, it also >whacks the diodes with a surge, though diodes are fairly tough, I don't >like to see the circuit dependent on external factors (such as whether >the customer has plugged it into an extension cord or not) to be reliable. > > >I would not be too concerned with the capacitor (C9) remaining charged as > >the approximate 6 mA current consumption from the voltage regulator will > >quickly discharge the capacitor. UL and TUV stipulate that the voltage > >potential on an unplugged power cord must diminish to 1/3 of the mains > >voltage within 10 seconds. So, If I wanted to increase the rate at which > >the capacitor discharges, I would place a resistor in parallel to (C5) on > >the low voltage side of the circuit. > >This will do nothing- the capacitor is in series with the low voltage >side when the plug is removed from the socket and the voltage will remain >too long to meet any kind of safety standards without a parallel resistor. >You won't see an approved design without it, or some equivalent. > > >I would want a 1/4 amp fuse between the 220 Vac main and the series > >capacitor (C9). > >A flameproof fusible resistor can probably be used to avoid the need for >that... >it has to be a high surge current type anyway (not metal film, but MOF >or wirewound). > > >I would also want the series capacitor (C9) rated for 800 V to 1000 V. > >Preferably with an AC rating > maximum line voltage. > > >If the series capacitor (C9) is getting warm at all, then the voltage > >rating should be increased. > >Yes, a film cap should never get warm. > >Have you gotten your "several amperes" supplies inspected by any >safety approval agencies? Are there any power factor specifications >that cause problems? > >Best regards, >=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= >Spehro Pefhany --"it's the network..." "The Journey is the reward" >RemoveMEspeffKILLspaminterlog.com Info for manufacturers: http://www.trexon.com >Embedded software/hardware/analog Info for designers: http://www.speff.com >Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com >=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-= > >-- >http://www.piclist.com hint: The list server can filter out subtopics >(like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

2001\07\27@141836 by Ned Seith

Phil, The 277 Vac is taken from 3 phase transformers and used to power fluorescent lights in extremely large facilities such as airports, high rise buildings, sports arenas, etc. Most extremely large facilities have a 277 volt bus that powers the entire facilities lighting. The 277 volt scheme presents a tremendous cost savings as individual lamp ballasts are not required. Other benefits include centralized power factor control and other power saving controls. LSI Lighting / Prescolite of San Leandro, California, USA is the world leader in 277 V bus power control technology. Sincerely, Ned Seith Nedtronics 59 3rd Street Gilroy, CA 95020 (408) 842-0858 G O T G A R L I C ? GILROY GARLIC FESTIVAL 2001 STARTS TODAY! >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> At 10:59 AM 7/27/01 -0500, you wrote: >sounds like the phase voltage of a three-phase 480V Y-connected supply.... > > > > {Original Message removed}

2001\07\27@152718 by Eisermann, Phil [Ridg/CO]

Right. And each phase is 277V. Now take three phases, 120 degrees (electrical degrees) out of phase, and connect them in a 'Y' with a common neutral. If you then measure the voltage between any two terminals (other than neutral), you'd get 480V. In other words, you're measuring the voltage between any two phases. Or am I misunderstanding you here? > {Original Message removed}

2001\07\28@013608 by jeethur

Looks like the main power hog in your circuit is the relay. Why not use a Solid state Relay or better yet build one using MOC3041 Triac Opto Coupler and A good old Triac ? An added benifit of this circuit is that MOC3041 gives you Switchover at Zero Crossing. Of course, I'm assuming that You want to switch AC mains. If not, forget this Idea. I've had the same problem with a PIC16f84A. And I'm using MOC3041 Reagrds, Jeethu Rao > {Original Message removed}

2001\07\28@022224 by Jinx

Alexandro, I assume you want the 12V for the relay ? Sorry, I've a ****load of mails to get through and haven't read all of those in this thread Consider my solution at http://www.piclist.com/techref/io/relays.htm (just before 1/2 way down the page) for energising a relay at its nominal voltage and keeping it closed with a holding voltage, which can be 50% of the energising voltage. The energising/holding ratio will differ from relay to relay so I can't promise success with yours -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

2001\07\28@041837 by Graeme Zimmer

> The concept and configuration of your series capacitance voltage divider > circuit is fine. It isn't fine. It relies absolutely on the Mains being clean AC with no harmonics present. If you are on a solid feed, it will probably work just fine. If you are on the end of a poorly regulated line, any AC hash will dramatically increase the current through the Capacitor. These things are a big headache for the Solar Power people. Imagine what will happen when someone tries to run it off a squarewave inverter. Zap !!! ............................. Zim -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

2001\07\28@142755 by Alexandre Domingos F. Souza

Ops, far away from home, now I'm back ;o) >Presumably you are using a relay with a low voltage coil. Why not ease the >low voltage current requirements by using a relay with a high voltage AC >coil. >If my presumption is correct then you will probably reduce your current >consumption on the 5 volt rail to 45mA or less. Use a small Triac or >thyristor to switch the relay. It would be great IF finding 110v coil relays could be found here in Brazil. We are in a country that your project has to be easyly changeable, since the component distribuitors bring to the market whathever they fit in their bills, and not always what the customer wants. Oh, so nice to live in a third world... ---8<---Corte aqui---8<---- Alexandre Souza taitoSTOPspamspam_OUTterra.com.br http://planeta.terra.com.br/lazer/pinball/ ---8<---Corte aqui---8<---- -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

2001\07\29@101720 by Chris Carr

> Ops, far away from home, now I'm back ;o) >>Presumably you are using a relay with a low voltage coil. Why not ease the >>low voltage current requirements by using a relay with a high voltage AC >>coil. >>If my presumption is correct then you will probably reduce your current >>consumption on the 5 volt rail to 45mA or less. Use a small Triac or >>thyristor to switch the relay. >It would be great IF finding 110v coil relays could be found here in >Brazil. We are in a country that your project has to be easyly >changeable, since the component distributors bring to the market >whatever they fit in their bills, and not always what the customer wants. >Oh, so nice to live in a third world... Everywhere has it's advantages and disadvantages. . As you have not knocked back my supposition that the relay is the major consumption of power then I will assume that the supposition is correct. The use of a Relay with a 110 volt coil is not an option due to unavailability. OK, presumably Relays with 5 volt, 12 volt or 24 volt coils are available. So why not energise them directly from the rectified 110 supply . Just apply pulses of 155 volts to the relay coil instead of a continuous 5,12 or 24 volt. Regards Chris Carr -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email spamBeGonelistservSTOPspamEraseMEmitvma.mit.edu with SET PICList DIGEST in the body

2001\07\29@224633 by Alexandre Domingos F. Souza

Learning, and learning, and learning... >Just change to a proper rectifier bridge, this will >double the current to 90mA. Then using a 30% larger >value of the main Xc cap will give you 120mA. >This web page has Traffic.PDF sent by Richard Ottosen >which shows a larger current Xc supply with a >full-wave bridge: >http://centauri.ezy.net.au/~fastvid/tube4w.htm Interesting, one more bit of knowledge, thanks ;o) >Remember the Xc supply ALWAYS runs full current, >so if your 120mA relay is OFF, something else >(large zener?) must be drawing the 120mA. Have a >serious think about this. Xc supply is best for >circuits that always draw the same current. This is something I didn't know I'm looking now for another approach: Using 2 relays of 24VDC in series (so, 48VDC) and using a wire wound power resistor and a diode. It will be activated thru an opto-triac. I think it will work. I'll test tomorrow ;o) Thanks anyway! ---8<---Corte aqui---8<---- Alexandre Souza KILLspamtaitospamBeGoneterra.com.br http://planeta.terra.com.br/lazer/pinball/ ---8<---Corte aqui---8<---- -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email EraseMElistservEraseMEmitvma.mit.edu with SET PICList DIGEST in the body

2001\07\29@231830 by Alexandre Domingos F. Souza

>> I've done one, some time ago, see >> http://www.geocities.com/vsurducan/c520.htm Vasile, I tried it but got no pictures, anything wrong? ---8<---Corte aqui---8<---- Alexandre Souza @spam@taito@spam@spam_OUTterra.com.br http://planeta.terra.com.br/lazer/pinball/ ---8<---Corte aqui---8<---- -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email spamBeGonelistservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

2001\07\30@011601 by Vasile Surducan

Ned, we are on the same wavelenght ! Cheers, Vasile On Fri, 27 Jul 2001, Ned Seith wrote: {Quote hidden}> Vasile, > > Your series capacitance voltage divider circuit has certainly received > criticism. > So I hope that I'm not kicking a dead horse. > While a transformer would definitely be the safest approach for the typical > hobbyist, I'm glad to see that there is someone who is willing to be more > intimate with the electrons. > The concept and configuration of your series capacitance voltage divider > circuit is fine. > I have designed industrial applications which have provided several amps of > current at low voltages from 220 Vac and 277 Vac mains using a series > capacitor. Industrial equipment and machines frequently use a series > capacitor instead of a transformer for providing lower voltages. > A few points: > I would not add a resistor in series with the capacitor (C9) as this will > vary the effective capacitance reactance which is providing the desirable > voltage drop and will also dissipate heat. > I would not add a resistor in parallel to the capacitor (C9) as this will > vary the effective capacitance reactance which is providing the desirable > voltage drop. This resistor would also dissipate heat. > I would not be too concerned with the capacitor (C9) remaining charged as > the approximate 6 mA current consumption from the voltage regulator will > quickly discharge the capacitor. UL and TUV stipulate that the voltage > potential on an unplugged power cord must diminish to 1/3 of the mains > voltage within 10 seconds. So, If I wanted to increase the rate at which > the capacitor discharges, I would place a resistor in parallel to (C5) on > the low voltage side of the circuit. > I would want a 1/4 amp fuse between the 220 Vac main and the series > capacitor (C9). > I would also want the series capacitor (C9) rated for 800 V to 1000 V. > If the series capacitor (C9) is getting warm at all, then the voltage > rating should be increased. > I would want the diode rectifiers voltage rating increased to 800 V to 1000 > V (1N4006, 1N4007) to assure that there is not any brief reverse conduction > during the delay of the capacitors charge cycle. > Otherwise, looks good to me. > Just a few comments from an old engineer. > > Sincerely, > Ned Seith > Nedtronics > 59 3rd Street > Gilroy, CA 95020 > (408) 842-0858 > G O T G A R L I C ? > GILROY GARLIC FESTIVAL 2001 ! > >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> > > At 12:10 PM 7/26/01 +0300, you wrote: > >I've done one, some time ago, see > >http://www.geocities.com/vsurducan/c520.htm > >at the bottom of the page, up to 150mA, but I don't recommend such power > >supplies for production devices ( maybe on 120V mains, only ) > >Note that in my design, the supply don't like to remain without load... > >Vasile > > > >On Thu, 26 Jul 2001, Roman Black wrote: > > > > > Alexandre Domingos F. Souza wrote: > > > > > > > > I designed a circuit with a PIC (12C508) that turns on and off a > > > >relay, controlled by an external source. The power to this circuit (around > > > >120mA) is a small transformer. I'd like to build a transformerless PSU > > into > > > >this circuit. But EVERY scheme I found on the internet was unusable. I saw > > > >something on the Embeeded Control Handbook from Microchip, but it only > > goes > > > >to (if I'm not mistaken) 45 mA. Maybe someone can help me to develop > > (or at > > > >least learn to) a simple transformerless PSU that 120mA. > > > > > > > > > Hi Alexandre! This can be done if you REALLY want > > > to do it. The Mchip app note shows 45mA, and that > > > is with a half-wave rectifier (two diodes). > > > > > > Just change to a proper rectifier bridge, this will > > > double the current to 90mA. Then using a 30% larger > > > value of the main Xc cap will give you 120mA. > > > This web page has Traffic.PDF sent by Richard Ottosen > > > which shows a larger current Xc supply with a > > > full-wave bridge: > > > http://centauri.ezy.net.au/~fastvid/tube4w.htm > > > > > > IMPORTANT! using a full wave rectifier will give > > > lethal voltages at ALL points of your 24v circuit. > > > You no longer have a reference ground! I know you > > > said you were using an optocoupler but remember at > > > all times this circuit is dangerous... > > > > > > Some handy points, you can get reliable relay > > > operation at half the hold current usng the old RC > > > trick, which gives it full current for pull-in > > > but only half current under hold. Costs one resistor > > > and one 470uF electro. Maybe this would get you > > > down to 60mA circuit current. I have used this trick > > > down to about 25% hold current. > > > > > > Remember the Xc supply ALWAYS runs full current, > > > so if your 120mA relay is OFF, something else > > > (large zener?) must be drawing the 120mA. Have a > > > serious think about this. Xc supply is best for > > > circuits that always draw the same current. > > > :o) > > > -Roman > > > > > > -- > > > http://www.piclist.com hint: PICList Posts must start with ONE topic: > > > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > > > > > > > > >-- > >http://www.piclist.com hint: PICList Posts must start with ONE topic: > >[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics > > -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestspam_OUTmitvma.mit.edu

2001\07\30@012454 by Vasile Surducan

On Fri, 27 Jul 2001, Spehro Pefhany wrote: > > >I would also want the series capacitor (C9) rated for 800 V to 1000 V. > > Preferably with an AC rating > maximum line voltage. Here we could talk a little... I don't know exactly if you have other technology for large value capacitors in AC usage, but here the only one I know is made by aluminium folia, shieleded by oil imersed, paper folia. And trust me, this one is not good because it has a large leakage current, this sort of capacitors are used only for filtering the mains and NOT for voltage dividers ! If you have PMP capacitors in AC range, this is different... Best regards, Vasile -- http://www.piclist.com hint: To leave the PICList TakeThisOuTpiclist-unsubscribe-request.....TakeThisOuTmitvma.mit.edu

2001\07\30@071145 by Alexandre Domingos F. Souza

>rise buildings, sports arenas, etc. Most extremely large facilities have a >277 volt bus that powers the entire facilities lighting. The 277 volt >scheme presents a tremendous cost savings as individual lamp ballasts are >not required. Other benefits include centralized power factor control and Fluorescent lamps? No ballasts? Could you give more info? ;o) ---8<---Corte aqui---8<---- Alexandre Souza TakeThisOuTtaitoKILLspamspamterra.com.br http://planeta.terra.com.br/lazer/pinball/ ---8<---Corte aqui---8<---- -- http://www.piclist.com hint: To leave the PICList .....piclist-unsubscribe-requestRemoveMEmitvma.mit.edu

2001\07\30@071148 by Alexandre Domingos F. Souza

>Consider my solution at >http://www.piclist.com/techref/io/relays.htm >(just before 1/2 way down the page) >for energising a relay at its nominal voltage and keeping >it closed with a holding voltage, which can be 50% of the >energising voltage. The energising/holding ratio will differ >from relay to relay so I can't promise success with yours Thanks Jinx, but reading your page, came to me the idea I said about the 24V relay connected directly to the 110V mains, using a diode and a resistor to drop the current. I think I got a winner here, I'll do some tests today ;o) ---8<---Corte aqui---8<---- Alexandre Souza RemoveMEtaitospamBeGoneterra.com.br http://planeta.terra.com.br/lazer/pinball/ ---8<---Corte aqui---8<---- -- http://www.piclist.com hint: To leave the PICList spamBeGonepiclist-unsubscribe-request@spam@spam_OUTmitvma.mit.edu

'[EE]:Transformerless PSU (+ question for repairmen'
2001\07\30@163245 by Jinx

> > for energising a relay at its nominal voltage and keeping > > it closed with a holding voltage, which can be 50% of the >Thanks Jinx, but reading your page, came to me the idea I > said about the 24V relay connected directly to the 110V mains, > using a diode and a resistor to drop the current. I think I got a > winner here, I'll do some tests today ;o) With the opto-triac for on-off control not much to go wrong there. My other thought would have been to have a cap supply for just the relay so there are no glitches on the 5V supply. I can usually find large (1-2uF) ones that I need in old SMPS or TVs I'd like to know this though. Which has the lower MTBF - X2 cap dropper or high watt resistor dropper ? I suspect the hi-W R for heat reasons but that's just intuitive and probably has more to do with PCB layout -- http://www.piclist.com hint: To leave the PICList TakeThisOuTpiclist-unsubscribe-requestspammitvma.mit.edu

2001\07\31@061217 by Roman Black

Jinx wrote: > >Thanks Jinx, but reading your page, came to me the idea I > > said about the 24V relay connected directly to the 110V mains, > With the opto-triac for on-off control not much to go wrong there. > My other thought would have been to have a cap supply for just > the relay so there are no glitches on the 5V supply. I can usually > find large (1-2uF) ones that I need in old SMPS or TVs > > I'd like to know this though. Which has the lower MTBF - X2 cap > dropper or high watt resistor dropper ? I suspect the hi-W R for > heat reasons but that's just intuitive and probably has more to do > with PCB layout Really, you could design either type for NO failure. Depends on the size and cost requirements. :o) I'd go for a good capacitor, with 10% of the drop done by a good qual series resistor running no more than 15'C temperature rise. Reasonably efficient, but gentle on the cap. Also use a snubber across the mains with a good mains cap and a smaller resistor. I've got units like this running for 15 years and never failed. -Roman -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2001\07\31@064631 by Vasile Surducan

On Tue, 31 Jul 2001, Roman Black wrote: > resistor. I've got units like this running for > 15 years and never failed. > -Roman > How old are you, Roman ? You have good advices... Vasile -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2001\07\31@070629 by Jinx

> > I'd like to know this though. Which has the lower MTBF > Really, you could design either type for NO > failure. Depends on the size and cost requirements. > :o) I think I may be biased towards Rs as they seem to look cruddier after a few years than caps. But as you say (and what I should have mentioned) is that you can over-spec a part to minimise stress > resistor. I've got units like this running for > 15 years and never failed Possibly an appliance as a whole was expected to live a shorter time than the PSU so some components were chosen for cost and simplicity. Say for example you have a TV that craps out after 10 years. The manufacturer may consider that a reasonable lifetime. Owner gets the fault repaired and off goes the TV for few years more, and all the while the power-handling components are going well past their expected service life. Although perhaps that was the case in the past - in these cheap import throwaway days that might not be so -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2001\07\31@111359 by Roman Black

Vasile Surducan wrote: > > On Tue, 31 Jul 2001, Roman Black wrote: > > > resistor. I've got units like this running for > > 15 years and never failed. > > -Roman > > > How old are you, Roman ? You have good advices... Thanks! :o) <changed topic to [OT]:> I'm 36 now! 5 could read 5-6 skipped couple years in school (in US would have been a "child prodigy" in Australia you just got "smart kid, miss a year") 10 started electronics hobby 1975 10 started high school (too young) 12 fixing anything with wires for family/friends 13 building/program computers with 8080, 6800, Z80 (remember soldering cpu and rams in veroboard? Programming with switches in binary?) 14 first in state, school technical shop (elect) 14 started TAFE basic electronics as night course (only person in Australia ever studied or graduated that course as a schoolchild) 15 electical technician (indust electrician) apprenticeship in industry, (had to get doctors certificate beacuse of age!) couldn't bear the thought of wasting 2 more years in school surrounded by children. 19 post trades industrial electronics microprocessor (one year) 19 qualified as elec tech + electrician After spending whole life in school and heavy industry I needed a break, lots of years of wild motorbikes, women, partying, living off my wits fixing anything, designing custom machinery and control gear, wacky inventions, musican, owned decent home studio, did real studio time playing guitar for others music, martial arts, bodybuilding, training others, some small businesses, somewhere in there did a couple of years of TV/VCR and studied anything technical I could. Wrote 2 bodybuilding books, owned a barter system, cowrote and published a financial magazine for 4 years, spent 3 years on a PC game team as graphics engine programmer in C, owned 4 TV repair shops (just closed the last one now), phew and that's only a bit of it, most of those things were done parallel to each other. Don't have a resume because I really don't think any stranger would believe it. :o) I like a challenge and love to soak up new skills, and quickly becoming the best at anything I try, or making a world-beating product. I like self learning, hate any classroom system as the learning pace is stupidly slow, I like new projects in totally new areas as it forces me to learn new stuff. I hate the slow way, hate easy things. Thats work... Sorry to rave on about me but you asked! Now what about you? Your posts have shown a huge electronics knowlege... :o) -Roman -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2001\07\31@112428 by Roman Black

Jinx wrote: > > resistor. I've got units like this running for > > 15 years and never failed > > Possibly an appliance as a whole was expected to live > a shorter time than the PSU so some components were > chosen for cost and simplicity. Say for example you have > a TV that craps out after 10 years. The manufacturer may > consider that a reasonable lifetime. Owner gets the fault > repaired and off goes the TV for few years more, and all > the while the power-handling components are going well > past their expected service life. Although perhaps that > was the case in the past - in these cheap import throwaway > days that might not be so So is Mr. Jinx planning a cheapy product? ;o) I would pull apart a few cheapy mains micro products, like electronic timers etc, look at how they do the Xc supply and make yours just that bit better. Should be good training for certification needs of the product too. Might even lead you to the right brands for the caps and semis too for cheap pricing. -Roman -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2001\07\31@135425 by Mike Kendall

My experience as a repair technician with over 19 years, is that the two most commonly failed items are power supplies and moving parts. If you live in an area with extremely high incidences of lightning storms such as New Orleans or Florida, your power supply may very well fail long before it's expected service life is up. Regards, Mike {Original Message removed}

'[OT]:Transformerless PSU (+ question for repairmen'
2001\08\01@194701 by Alexandre Domingos F. Souza

>10 started electronics hobby 1975 Wow, I was one year old! :o) >inventions, musican, owned decent home studio, did >real studio time playing guitar for others music, Why almost all (good) technicians I know are involved in some kind of music? >TV/VCR and studied anything technical I could. Wrote 2 >bodybuilding books, owned a barter system, cowrote and Bodybuilding? Do you still find free time? >Sorry to rave on about me but you asked! Have you had time to go to bathroom between all these activities? Maybe some sleep? :o))) ---8<---Corte aqui---8<---- Alexandre Souza taitoEraseMEterra.com.br http://planeta.terra.com.br/lazer/pinball/ ---8<---Corte aqui---8<---- -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics

2001\08\02@061359 by Roman Black

Alexandre Domingos F. Souza wrote: > > >10 started electronics hobby 1975 > > Wow, I was one year old! :o) > > >inventions, musican, owned decent home studio, did > >real studio time playing guitar for others music, > > Why almost all (good) technicians I know are involved in some kind of music? > > >TV/VCR and studied anything technical I could. Wrote 2 > >bodybuilding books, owned a barter system, cowrote and > > Bodybuilding? Do you still find free time? > > >Sorry to rave on about me but you asked! > > Have you had time to go to bathroom between all these activities? Maybe some sleep? :o))) No time for the gym lately i'm afraid. Or the guitar either. And sleep?? Yes I remember that! ;o) -Roman -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

More... (looser matching)
- Last day of these posts
- In 2001 , 2002 only
- Today
- New search...