*Power supply question*

caesar

Hello,
·· Because·it·has·more than the 12vdc 2amps minimum needed for my drill motor. I was wondering...
Are there any drawbacks with using an ATX computer power supply to power both my drill motor and a Basic Stamp?
I believe a 10-15 ohm, 1 watt resister should reduce the 12vdc to 9vdc 300ma for the Stamp. And since the power supply was designed for a PC, I think it would already be filtered(clean).

Any thoughts?
Thanks!·

Mike Green

PC power supplies are not designed for this use, but people have adapted them. The biggest problem is that the +5V supply is the primary supply and often the other voltages are regulated relative to this. There's usually a minimum drain on the +5V supply required for proper operation. Search the web for articles on adapting PC supplies for general benchtop use. Do add fuses for all the outputs. Depending on the capacity of the supply, the difference between a benchtop supply and a small arc welder is a matter of opinion.

caesar

Hello,

Definitely would be fusing·everything. My ATX ps is rated for 12vdc @ 12amps & 5vdc &·7amps WOW! definitely overkill.

But it's a free ATX power supply. I was hoping to power the whole project with it.

What's the most inexpensive way to power my 2-3 amp drill motor? Should I just buy one of those RadioShack 12vdc regulated power supplies?

Thanks!


Post Edited (caesar) : 8/23/2008 6:04:37 AM GMT

sam_sam_sam

caesar
Should I just buy one of those Radio Shack 12vdc regulated power supplies?

Once upon a time I thought this was a good ·BUT it not to use a regulated power supplies you are asking for trouble I have fryed the regulators
in these type before you cause they to over heat

You can do this on any transformer ONE Amp and above

·Your best bet is to take a transformer that is 18 volts an with a rectifier and cap and remove enough of the secondary winding on
that transformer so that when your drill motor is running it is 12 volts yes this is a little work but it works

You can try a 12 transformer first and see if this will have enough voltage

This is my 2 cents worth on this

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··Thanks for any··that you may have and all of your time finding them

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Sam

Post Edited (sam_sam_sam) : 8/24/2008 1:36:51 AM GMT

jpyle

If you want to go with computer power supply (switcher), for sure fuses--- and the easiest, quickest, safest, most reliable way to provide the needed resistance to run is to just plug a hard drive into any molex plug. Do not wory about the 40 pin data flat cable--not needed. This gives you a load that was designed to work with the power supplies with no guesswork about resistance needed. This just covers the load\resistor aspect. Use extreme caution with any other changes in or out of the case.
I have used converted PSUs for years. BE VERY AWARE of the LETHAL voltages within the case, and if not comfortable with the
changes then ASK, GOOGLE, RESEARCH and be sure of what you do. I would not recommend running motors from a PSU. Just my two cents worth. John

caesar

Hello,
Maybe I'm missing something...·· But I don't seem·to need·a resistance type load to·enable the power supply.
There's just 2 pins on the·main connector that need to be·jumped. Then the·power supply comes fully alive.
It must not be a "load sensing" supply.
I'm still going to persue a different power source, but I thought it seemed odd that everyone mentioned having some type of load to enable the power supply.
Thanks!


Post Edited (caesar) : 8/26/2008 12:06:59 AM GMT