Electronics > Beginners
DIY power supply
MarkF:
--- Quote from: Pirateguy on August 15, 2018, 07:45:56 pm ---i was thinking i would have a selector switch between differently rated fuses.
one limited to something appropriate for micros and something a little stronger for motors n stuff like that.
--- End quote ---
I don't know if that would be worth while. If you really want different current capability outputs, I would have separate output jacks. It is far too easy to overlook a switch position.
You could put a high current output and the variable voltage output off to the side to distinguish the difference.
--- Quote ---i was thinking of using the breakout boards cuz they come with a regulator for each output.
isn't that also a way to limit the current?
--- End quote ---
The current limiting capabilities of those breakout boards is probably only a thermal shutdown. Far too late to save you. Just stick with the ATX outputs and fuses. Just speculation not knowing the exact boards you are referirng to.
I prescribe to the K.I.S.S. (keep it simple stupid) theory.
MarkF:
Here's is a possible panel layout:
I agree with having a 3/4" horizontal spacing between the jacks.
There is a high chance you would use the double banana plugs at some point.
sureshot:
Once you've done your wire grouping and or binding posts, preload options...
If you choose the atx route how about this below.
Rotary switch is break before make configuration.
rhb:
I suggest visiting thrift stores and looking for an old piece of audio gear that's cheap. Those will usually have a good transformer for a linear supply. Another option is to rewind the secondary of a microwave oven transformer. That will certainly give you 0-40V at 5 A provided you add a *large* pass transistor to the LM317 with a big heatsink. For the fixed stuff just use the ATX.
Adjustable current limiting is not difficult. For the ATX, use a comparator, a sense resistor voltage divider pot and flip flop so if overcurrent is detected it toggles the flip flop and disables the PSU power enable line until you press a reset button.
I think it would be wise to start with the ATX as a base, but in a large enough case that you can add an adjustable linear supply later. The layout by MarkF looks very practical. Get some cheap DMMs and add switching to monitor voltage and current using those minus the cases.
Pirateguy:
these are the boards i was talking about:
https://www.ebay.com/itm/5Pcs-DC-DC-12V-To-3-3V-5V-Buck-Step-down-Power-Supply-Module-For-Arduino-/352280409059?var=&hash=item0
my thinking was that instead of blowing a fuse when u use too much this would just limit the current and not deliver more then it can.
seems to make more sens then replacing fuses... although i would include those too in case of anything malfunctioning in the PSU or something like that.
so i went over the fuses i have, and looked up the codes n stuff.
apparently they come in speed ratings, are the slow ones ok for this?
also lemme see if i got anything wrong here:
remove access wires, combine multiple rails of the same output, run a wire for each output to a fuse, and from there to the jacks?
and for the variable the fuse goes between the atx and the regulator?
--- Quote from: rhb on August 16, 2018, 12:33:53 am ---I suggest visiting thrift stores and looking for an old piece of audio gear that's cheap. Those will usually have a good transformer for a linear supply. Another option is to rewind the secondary of a microwave oven transformer. That will certainly give you 0-40V at 5 A provided you add a *large* pass transistor to the LM317 with a big heatsink. For the fixed stuff just use the ATX.
Adjustable current limiting is not difficult. For the ATX, use a comparator, a sense resistor voltage divider pot and flip flop so if overcurrent is detected it toggles the flip flop and disables the PSU power enable line until you press a reset button.
I think it would be wise to start with the ATX as a base, but in a large enough case that you can add an adjustable linear supply later. The layout by MarkF looks very practical. Get some cheap DMMs and add switching to monitor voltage and current using those minus the cases.
--- End quote ---
could i just yank the whole setup out of an extension cord that has that feature?
with large pass transistor, do you mean one that lets through a lot of current?
i have some 2N3055 ones that look pretty beefy...
for power monitoring i have a couple of panel units that show volts and amps at the same time.
for now i think i will build it all into the original ATX case as i don't have anything else right now,
and i want to take my time finding something that looks nice.
there is enough room though for a regulator circuit to do a limited variable output of 10v as suggested below.
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