Post by thread:power supply

Keith Causey wrote: > Every Thrift Shop I ever go in has a full bin of orphaned wall warts > of every conceivable description for prices ranging from $0.25 to > $3.50. You mean "Every Thrift Shop I ever go in *had* a full bin"! Also - think "Garage Sales" - yeah, time consuming but fun. I gave $5 yesterday for a shopping bag containing a Sinclair ZX Spectrum with printer, many books etc. One more for my museum collection. :) Another slight annoyance comes to mind - I can't remember where I *put* my box of Plug Packs. My collection of those includes several with Euro and British pinouts (or indeed, pin-ins). I need some sockets for those. Mark Willis wrote: > I usually use DC 'wall warts' - Interesting! I hadn't measured an AC > one, I just let someone else use those, usually. I didn't anticipate > any real drop in voltage - guess I forgot about internal resistive > losses inside the transformer, which is already part of why a DC > plugpack "peaks" sans load. Need a vacation here, obviously <G> General principle is: *All* transformers sag under load. Small ones do so a *lot*, and those in plug packs/ wall warts are *consumer* appliances rated at unconscionably high temperatures. It follows the internal electrolytics dry out fast under constant use too. You could argue they are really not made for continuous all-day use, and if you have a *serious* application you should under-rate them to 50% at which point they must be over specified voltage. You're not going to use them to power logic circuitry without regulation anyway. It's not an option. Your motor doesn't care whether it gets 10V or 14V anyway (or if it does then *it* needs a regulator too). Remember too that the mains itself varies a *lot*. > or skip the fuse & let the plugpack's diodes blow if you must Even 1A plugpacks generally have diodes that can withstand the short- circuit current quite well. on less than 500mA devices I'd say it's guaranteed the transformer will burn first. You're using the transformer winding as the fuse! (Nowadays contains a thermal fuse.) > I like the recent trend to try to use different plugs for different > voltage ranges; Even though it is a pain in terms of finding all > those sockets, makes it less likely that someone will plug a 15VDC > plug into their 4.5VDC device, then complain to the manufacturer about > poor design quality <G> Eh? First I've heard of this! As far as I can see, it's a lost cause. 20 years ago I tried for my own equipment to use 2.1mm coaxial fittings for 12V and 2.5mm for anything less, but there has never been any standardisation. Worst of all are manufacturers who make the centre pin negative. I have been known to go so far as to re-wire internals to correct for safety this foolish polarity on equipment. > Hoping Chris gets a new plugpack! 200mA into one amp definitely won't go. He'll need it. -- Cheers, Paul B.

Paul B. Webster VK2BZC wrote: > > Keith Causey wrote: > > > Every Thrift Shop I ever go in has a full bin of orphaned wall warts > > of every conceivable description for prices ranging from $0.25 to > > $3.50. > > You mean "Every Thrift Shop I ever go in *had* a full bin"! <G> I resemble that too! > Also - think "Garage Sales" - yeah, time consuming but fun. I gave $5 > yesterday for a shopping bag containing a Sinclair ZX Spectrum with > printer, many books etc. One more for my museum collection. :) > > Another slight annoyance comes to mind - I can't remember where I > *put* my box of Plug Packs. My collection of those includes several > with Euro and British pinouts (or indeed, pin-ins). I need some sockets > for those. I'd zing over & help look, but... <G> {Quote hidden}> Mark Willis wrote: > > > I usually use DC 'wall warts' - Interesting! I hadn't measured an AC > > one, I just let someone else use those, usually. I didn't anticipate > > any real drop in voltage - guess I forgot about internal resistive > > losses inside the transformer, which is already part of why a DC > > plugpack "peaks" sans load. Need a vacation here, obviously <G> > > General principle is: *All* transformers sag under load. Small ones > do so a *lot*, and those in plug packs/ wall warts are *consumer* > appliances rated at unconscionably high temperatures. It follows the > internal electrolytics dry out fast under constant use too. You could > argue they are really not made for continuous all-day use, and if you > have a *serious* application you should under-rate them to 50% at which > point they must be over specified voltage. Cheap to replace, tho <G> I'm "spoiled", when growing up I always had these 10-12 huge 12.6VAC 15A (or more) "can" transformers around - as in about 15 of them - that I used, I think those things had about .02A internal resistance, you could make NiCad wire glow pretty well off that! <G> (If not turn it to plasma in short order.) Those things were about a foot on a side, mil surplus or some such I think, pretty robust units. Sure would power any project I cared to wire to them! Tube filaments, no problems <G> {Quote hidden}> You're not going to use them to power logic circuitry without > regulation anyway. It's not an option. Your motor doesn't care whether > it gets 10V or 14V anyway (or if it does then *it* needs a regulator > too). > > Remember too that the mains itself varies a *lot*. > > > or skip the fuse & let the plugpack's diodes blow if you must > > Even 1A plugpacks generally have diodes that can withstand the short- > circuit current quite well. on less than 500mA devices I'd say it's > guaranteed the transformer will burn first. You're using the > transformer winding as the fuse! (Nowadays contains a thermal fuse.) A friend messed up & blew the diodes on a ComputerGate 12V 1A DC plugin, running his AC/DC Television. He replaced them with 3A Schottky's and is still using the whole mess; Hasn't blown up (yet.) I think a startup surge nailed the diodes? Man, the things he'll do to not spend $10 for a better power supply <G> {Quote hidden}> > I like the recent trend to try to use different plugs for different > > voltage ranges; Even though it is a pain in terms of finding all > > those sockets, makes it less likely that someone will plug a 15VDC > > plug into their 4.5VDC device, then complain to the manufacturer about > > poor design quality <G> > > Eh? First I've heard of this! As far as I can see, it's a lost > cause. 20 years ago I tried for my own equipment to use 2.1mm coaxial > fittings for 12V and 2.5mm for anything less, but there has never been > any standardisation. Worst of all are manufacturers who make the centre > pin negative. I have been known to go so far as to re-wire internals > to correct for safety this foolish polarity on equipment. Hate that too, I prefer center pin + as well. I'll see if I can find that table, anyone else seen that Barrel/Pin size vs. Voltage suggestion table? I'll keep an eye out. > > Hoping Chris gets a new plugpack! > > 200mA into one amp definitely won't go. He'll need it. > -- > Cheers, > Paul B. Mark -- I do small package shipping for small businesses, world-wide.

Just buy a Bigger label and write the Voltage and Amperage if using for project power supplies, or what product it belongs to ZIP, EPROM eraser (I wouldn't want to use my 24VAC wall wart with the PicStart Plus...) The PIC would get Flashed alright... Mark Willis wrote: {Quote hidden}> > I just add that sticker myself (laser-print & use shipping tape, sticks > right on there nicely.) Solves the problem, but I agree, should be > either a sticker, or just hot branded on there, before we get the > product. I've been known to wire tie the power lump to the product <G> > > Mark > > William Chops Westfield wrote: > > > > Manufacturers of any size who use wall-warts could improve their products > > a great deal by simply providing a sticker that would fit on the wart and > > identify WHICH product it belonged to! > > > > :-( > > BillW > > -- > I do small package shipping for small businesses, world-wide. -- Jason ======================================== Website: http://www.execpc.com/~milsumai E-Mail: spam_OUTmilsumaiTakeThisOuTexecpc.com ICQ # : 12978762 ======================================== .:::. ,,, _(- -)_ / ( ) \ \_/ : \_/ |_/ \_| | | | -TRY PRAYER-