Need help with help homemade bench power supply problem

[Brumby]

How about this. ? Could I build a box with a bunch of wall warts wired in a parallel on the input side and run all the outputs to a 4 to 1 pin rotary switch thus just selecting a different wall wort? Is it ok to hook them in parallel on the input side  ?

I assume you are talking about plugging 4 wall warts into a power board (or an equivalent arrangement.)

Not a pretty idea ... but it should work.  Just make sure you don't connect any outputs of the wall warts in parallel.


Seriously though, please consider getting a real lab-style supply.  You'll be over the moon.

[janoc]

Was wanting to make a sort of all purpose supply cheep for use in the shop. Small motors lights gadgets. Battery powered drills are almost discarded by people because when the battery packs that are more $ than the drill no longer take a charge they are practically given away. I have about 4 that I have found for less than 5$. And have gotten one to run great off of a laptop power supply. But have it permanently wired into the gutted battery pack. And it's output is to high for smaller jobs. So the ATX with switchable volts is kinda ideal for the task I do. If I could just get them to work on all the different volt settings. The "wimpy one" I built would be ok for other things if the 5v and 12v wouldn't shut the device off? Even a small 12v light will kill it? A 12v RC car motor shuts it off. So would a 600w ATX perform those task ?

If this is what you want, then a modern ATX supply with a sufficiently powerful 12V rail (15-20A or more rated) could do the job. However, most battery powered drills need more than 12V (14-19V being typical) and there is not really a good way to get that out of an ATX supply cheaply and safely, especially with your level of experience. The drill may run at 12V, but it will very likely lack power to the point of being unusable. Only the smallest cordless screwdrivers run at voltages lower than 10V or so.

If you post the ratings of your drills, then some more specific advice could be given - e.g. an industrial power supply with a fixed voltage and sufficient power rating could be an option. Then have a second adjustable supply for your low power things.

However, without knowing more about the type of drills or motors you want to power it is shooting in the dark. "Battery drill" or an "RC motor" is too vague - RC motor could be a small DC servo taking milliamps of current but also a large brushless motor drawing 100+ amperes ...

How about this. ? Could I build a box with a bunch of wall warts wired in a parallel on the input side

A wall wart is extremely unlikely to have sufficient power to run a drill. You will most likely fry the wall wart if you try it, especially if you have bought some cheap junk ones without much of an output protection.

[James k]

Ok so for the selectable wall wort idea. Is it ok to have the negative output wires of 4to5 wall warts connected to one banana plug? And the positives connected to a 5 to 1 pole rotary switch and from that to a banana plug ? Or will there be any kinda flow back from the negative wires all being joined ?

[Brumby]

There shouldn't be any problems doing that.

[James k]

So in the selectable wall wort box idea, could all the black - output wires of 4-5 be joined together at one banana plug and all the red + wires go to a 5 to one pole rotary switch only powering one at a time to get different volts. Or would it create flow back into other wall worts ?

[James k]

Brumby that goes for laptop supply's as well? Because I do have one that powers a drill very well even under load like drilling thick wood and metal. It would be ok to combine that one into the box with the other wall worts?