Electronics > Beginners
DIY power supply
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Old Printer:

--- Quote from: MarkF on August 15, 2018, 01:18:40 am ---I do like these little HP Supplies.  Not a lot of power but without a fan, they are quiet and don't take up much space.
   HP 6216A Power Supply

--- End quote ---

Ditto on the little HP's. The 6216A is good for about a half amp at 24 volts. Has both voltage and current modes, each having coarse and fine adjustments. Very well documented which is easily available online. Operation, service & schematics. With a little patience they can be had in nice shape for $50 shipped on ebay. I bought three last winter like that for my bench in a spare bedroom. Quiet and compact, built like a tank and easy to repair.
Pirateguy:
 |O
Jwillis:
Seems when you start to make progress you get cornered by more salesmen .I feel your pain.....Anyway.
Ok so your +5V and +12 volt will give you the most current .3 volt will probably only be a few miliamps .You can load one of the +5 volt lines with a 5 to 10 Watt power resistor connected to ground.
Difficult to say what the potential current is. Current limiting is nice to have, but not completely necessary.Unless you create dead shorts your projects will only draw as much current as it requires .You can always put in short circuit protection later if you like.
We can start by tying the yellow wires together and the black wires together.tie all the red ones together except one .We'll use that for the 5-10 Watt 10 Ohm resistor.If  yours has a switch you can use that one or shorten the bundle and use a similar switch put through the ATX case.You can use a LED and a 1 or 2k resistor for each voltage if you like to indicate which voltage you switched to.Will also indicate power on.For variable power try a buck boost variable regulator..
Maybe consider a larger enclosure than the stock enclosure.Things will most likely get pretty cramped inside.
MarkF:

--- Quote from: Jwillis on August 15, 2018, 05:47:51 am ---Seems when you start to make progress you get cornered by more salesmen .I feel your pain.....Anyway.
Ok so your +5V and +12 volt will give you the most current .3 volt will probably only be a few miliamps .You can load one of the +5 volt lines with a 5 to 10 Watt power resistor connected to ground.
Difficult to say what the potential current is. Current limiting is nice to have, but not completely necessary. Unless you create dead shorts your projects will only draw as much current as it requires .You can always put in short circuit protection later if you like.
We can start by tying the yellow wires together and the black wires together.tie all the red ones together except one .We'll use that for the 5-10 Watt 10 Ohm resistor.If  yours has a switch you can use that one or shorten the bundle and use a similar switch put through the ATX case.You can use a LED and a 1 or 2k resistor for each voltage if you like to indicate which voltage you switched to.Will also indicate power on.For variable power try a buck boost variable regulator..
Maybe consider a larger enclosure than the stock enclosure.Things will most likely get pretty cramped inside.

--- End quote ---

Fuses or No Fuses?

An ATX Power Supply has almost the same current capabilities as my MIG Welder!  If you drop a wire into a project you're testing, short the wrong pins with a probe, or a wire comes loose on a solderless breadboard -- FIREWORKS.  Accidents happen.  The polyfuses the OP has would be a must in my book.  As I mentioned earlier the ATX Breakout board has the polyfuses, ATX power connector, load resistor (if needed), On/Off Switch and LED power on indicator.  Just plug and play. No need to modify the power supply or cutting off connectors and dealing with tying off unused wires.

   

From everything the OP mentioned, the ATX power supply would probably be the cleanest way to go over the wall-warts.  I can also envision projects that require multiple voltages.  NOT a rotary switch with a single output.

The OP has a lot of suggestions of what "to do" and "not do".  Plus several options of low cost items that are available to purchase.  If this all seems like too much to take in, I would stay far away from the high voltage projects mentioned!  I'm sorry if this comes off mean spirited.  It's not meant to be.  Just trying to point out the dangers.
Pirateguy:
well my ATX is onlu 200watt, but that still plenty to set my projects (and me) on fire.
some years there was a death in the family and i inherited a bunch of electronics stuff from this person.
including a bunch of fuses.

do those things age when not in use?
and what kind of values am i looking for?

to clarify: i want BOTH a selectable fixed voltage that i can dial in with a switch AND
a variable output that i can set with a pot.
the variable output at least will have a little panel v/a meter to tell me what is going on and the unit will have a temp display.

if i understand correctly you are saying it is better to have each output with it's own binding posts
cuz i might need to use several at the same time?

i have some breakout boards for stepping down to 3.3 and 5v for arduino. i am considering including one of those
and drawing the 3 and 5v from there instead of directly from the atx.
and for the variable output i have 317 and 338 regulators.

maybe i should make it so i can switch between a 5amp 338 one and another limited to lower current?

right now the only high voltage stuff i am screwing around with is all powered by those cheapo stun gun modules off ebay:
particularly these 2:
https://www.ebay.com/itm/15KV-High-Frequency-Inverter-Generator-High-Voltage-Electric-Ignitor-Coil-Arc/382475346892?ssPageName=STRK%3AMEBIDX%3AIT&var=651230490166&_trksid=p2057872.m2749.l2649
https://www.ebay.com/itm/High-Voltage-Pulse-Generator-Inverter-Module-Super-Arc-Pulse-Ignition-Coil-DH/362195494965?ssPageName=STRK%3AMEBIDX%3AIT&var=631407328312&_trksid=p2057872.m2749.l2649

neither of those have the cap built in and they are basically like arc lighters and will run off 2xAA.

what i want right now is to see how i can incorporate sparks as special effects for dioramas, so
it's gotta be low power anyway. dioramas tend to be fairly flammable :P
so part of the scope of my high voltage projects is to see how low i can get the amps and still have cool looking sparks.

this stuff is indeed overwhelming, especially for me as i have ADD.
that's kinda why i came here; to plan things out ahead of time (after having it checked for stupidity)
and work systematically, 1 step at a time.
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