Post by thread:[EE]: is it really not DC, so what can I do ?

on 29/12/01 12:55 AM, Tal Bejerano - AMC at spam_OUTkooterTakeThisOuTZAHAV.NET.IL wrote: Tal, > does anyone saw on the 'net simple switching PSU circuit? > I know I have to do some coil stuff, but it worth it. > Helllllpppppppppp Are you looking for just one or thousands? What voltage(s) do you need, for what application and at what currents? If just one, I would follow the advice of others that have replied to you and NOT use that unit you have - especially for experimenting. A cheap (approved) "plug pack" or "wall wart" would be a safer option for you. Regards, Sean -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

on 29/12/01 1:16 AM, Tal Bejerano - AMC at .....kooterKILLspam@spam@ZAHAV.NET.IL wrote: Hi Tal, > I am looking for a PSU to supply 12VDC for my MP3 Car Player at home, I > measure it's current consumption and found that it consume about 5A. I want > to build it my self cause it's very expensive to buy it ready made. > Just looking for a site with such circuits. OK, I'll see what I can do for you. It's late in this part of the world, so I will take a look in the morning. Regards, Sean -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Thanks Sean I am waiting Tal -----Original Message----- From: pic microcontroller discussion list [PICLISTKILLspamMITVMA.MIT.EDU]On Behalf Of Sean Alcorn - Avion Sydney Sent: Friday, December 28, 2001 4:28 PM To: .....PICLISTKILLspam.....MITVMA.MIT.EDU Subject: Re: [EE]: is it really not DC, so what can I do ? on 29/12/01 1:16 AM, Tal Bejerano - AMC at EraseMEkooterspam_OUTTakeThisOuTZAHAV.NET.IL wrote: Hi Tal, > I am looking for a PSU to supply 12VDC for my MP3 Car Player at home, I > measure it's current consumption and found that it consume about 5A. I want > to build it my self cause it's very expensive to buy it ready made. > Just looking for a site with such circuits. OK, I'll see what I can do for you. It's late in this part of the world, so I will take a look in the morning. Regards, Sean -- 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

Tal, I'd recommend building a power supply, especially if you have not built one before. If you have, then ignore this message. When I hire a new technician, I tell him he'll be needing a variable power supply for his bench, and he must build one. It's sort of a rite of passage, and if the guy can do a neat wiring job on his benchtop wonder, then he's good enough to wire something else. Building them is a good exercise for the new engineer. I often start with a car battery charger. Good high amperage transformer, heavy diodes, and a case, all in a cheap mass produced package. Add a voltmeter, a few capacitors, inductor, big pass transistor, a PIC and a knob, and you've got a nice bench power supply. Of course if this is "old hat" to you then just go buy one. --Lawrence ----- Original Message ----- From: "Tal Bejerano - AMC" <kooterspam_OUTZAHAV.NET.IL> To: <@spam@PICLISTKILLspamMITVMA.MIT.EDU> Sent: Friday, December 28, 2001 9:54 AM Subject: Re: [EE]: is it really not DC, so what can I do ? > Hi Herbert! > > Where i can finf 5$ PSU ? > If u can give me a site that sell those PSUs i will buy it. > > Tal > > > {Original Message removed}

I'm not sure where you are from; but used PC-AT type PSU's can be had at most computer shops for almost nothing. Another place to look is thrift stores --for me, this used to be a good place to find large transformers --old satellite dish positioning motor power supplies. The disposable age has been kind to me... If you want to online order, a few other places to look: http://www.alltronics.com, http://www.jameco.com , http://www.candhsales.com , http://www.allelectronics.com ----- Original Message ----- From: Tal Bejerano - AMC <KILLspamkooterKILLspamZAHAV.NET.IL> To: <RemoveMEPICLISTTakeThisOuTMITVMA.MIT.EDU> Sent: Friday, December 28, 2001 8:54 AM Subject: Re: [EE]: is it really not DC, so what can I do ? > Hi Herbert! > > Where i can finf 5$ PSU ? > If u can give me a site that sell those PSUs i will buy it. -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

> why do you need the pic? cant you just use like a few capacitors, a > rectifier (or 4 diodes, depending) a LM317 Been there, done that, got the T-shirt, wore it out, sold it to Goodwill. LM317's are simple, but they won't handle more than an amp, won't dial down to less than 1.2 volts, pots are hard to adjust in tiny increments, and LM317's are linear so they waste lots of power. I've prolly built a dozen supplies with them. You won't get 5 amps out of an LM317 without a bunch of extra parts. I built a nice little bench supply with a PIC running a P-Channel pass transistor, threw in an inductor and a capacitor and two pushbutton inputs to the PIC. The PIC senses output voltage, and turns the pass transistor on and off. The two pushbutton inputs run the setpoint up and down. A little digital panel meter serves as the interface, you just push the UP button if you want the voltage higher, etc. None of the part values seemed to be very critical, worked pretty good first time with junk parts off my bench. Running behind a stable 24V power source it seems to give pretty good regulation and will provide lots of current if required, will dial down to less than .25 volts, and can be adjusted in micro-increments. Used a 16F873 so I could use the 10 bit A/D for lots of fine adjustment. Of course there are 1000 circuits using LM317's plus pass transistors. I just wanted to build a switcher with a PIC in it, so I could slap a sticker on it saying "PIC INSIDE!" --Lawrence -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

Can we have the details? ie schematic? Thanks, David Lawrence Lile wrote: {Quote hidden}> > why do you need the pic? cant you just use like a few capacitors, a > > rectifier (or 4 diodes, depending) a LM317 > Been there, done that, got the T-shirt, wore it out, sold it to Goodwill. > LM317's are simple, but they won't handle more than an amp, won't dial down > to less than 1.2 volts, pots are hard to adjust in tiny increments, and > LM317's are linear so they waste lots of power. I've prolly built a dozen > supplies with them. > > You won't get 5 amps out of an LM317 without a bunch of extra parts. > > I built a nice little bench supply with a PIC running a P-Channel pass > transistor, threw in an inductor and a capacitor and two pushbutton inputs > to the PIC. The PIC senses output voltage, and turns the pass transistor on > and off. The two pushbutton inputs run the setpoint up and down. A little > digital panel meter serves as the interface, you just push the UP button if > you want the voltage higher, etc. None of the part values seemed to be very > critical, worked pretty good first time with junk parts off my bench. > > Running behind a stable 24V power source it seems to give pretty good > regulation and will provide lots of current if required, will dial down to > less than .25 volts, and can be adjusted in micro-increments. Used a 16F873 > so I could use the 10 bit A/D for lots of fine adjustment. > > Of course there are 1000 circuits using LM317's plus pass transistors. I > just wanted to build a switcher with a PIC in it, so I could slap a sticker > on it saying "PIC INSIDE!" > > --Lawrence > > -- > 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

> very expensive 5A 12V supply It costs less than $40 (<180 NIS at current rate) including all taxes and delivery probably. If you want to make your own it is a good learning project but maybe you should not start with a smpsu ... Buying the parts separately will get yuo to the same price level (150W toroidal halogen transformer, bridge, capacitors, LM... + transistor series regulator, board, case, connector, switch). 0.02 Agorot, Peter PS: Check that current spec, it is more than likely not 5A continuous. You want to know the RMS rating for continuous power. -- 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

>You won't get 5 amps out of an LM317 without a bunch of extra parts. Maybe you can get from the TO-3 LM317. But be sure you gotta use a BIG active heatsink (e.g.: with a fan) >I built a nice little bench supply with a PIC running a P-Channel pass >transistor, threw in an inductor and a capacitor and two pushbutton inputs >to the PIC. The PIC senses output voltage, and turns the pass transistor >on >and off. The two pushbutton inputs run the setpoint up and down. A little >digital panel meter serves as the interface, you just push the UP button if >you want the voltage higher, etc. None of the part values seemed to be >very >critical, worked pretty good first time with junk parts off my bench. Hmmm, Miss the times where we used simple zeners or UA723 for regulating power ;o) >Running behind a stable 24V power source it seems to give pretty good >regulation and will provide lots of current if required, will dial down to >less than .25 volts, and can be adjusted in micro-increments. Used a >16F873 >so I could use the 10 bit A/D for lots of fine adjustment. Wow, that's nice! ;oD >Of course there are 1000 circuits using LM317's plus pass transistors. I >just wanted to build a switcher with a PIC in it, so I could slap a sticker >on it saying "PIC INSIDE!" Hahaha, nice touch ;o) ---8<---Corte aqui---8<---- Alexandre Souza spamBeGonetaitospamBeGoneterra.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.