Testing Power Supplies! Re: Norsk Data Nord-10/S restoration

From: Joe R. <rigdonj_at_cfl.rr.com>
Date: Tue Nov 16 19:57:52 2004

   Ok for the ones of you that didn't get it I was being sarcastic. That's why the smiley at the end of the message. I just wondered what the reaction to trying to find a .0333 Ohm 750 Watt resistor would be. FWIW I once made such a resistor out of paralleled incandescent heaters when I was in a small town in Virginia that didn't have anything other than a small town hardware store. IIRC it took about ten or eleven heaters in parallel to get a low enough resistance.

   Incandesent bulbs are a good idea but you have to be careful. Their resistance isn't linear and varies widely depending on the voltage. That makes them dammed difficult to use accurately. The same applies to the heaters that I used but luckly I had a GOOD ampmeter and voltmeter.

    Joe


At 12:30 AM 11/17/04 +0000, you wrote:
>> OK I just picked up some computers with 150 Amp 5 volt supplies. Now
>> figure out the necessary resistrance and wattage and go find me a
>> resistor :-)
>
>Now what I'd do there is very simple...
>
>6V car headlamp bulbs tend to have 36W filaments, and double-dippers with
>2 36W filaments are not uncommon. For short periods (like testing PSUs)
>you could run both filaments together. And light bulbs approximate to
>constant current devices, so I would guess they'd take 6A (each filament)
>from a 5V supply too. Or thereabouts.
>
>I'd normally test a PSU at around half its rated current, so around 75A.
>Each bulb (both filaments) takes 12A, so use half a dozen of them. And
>yes I do keep such bulbs in stock for testing such PSUs (my I2S image
>processors have such a PSU module for each crate...)
>
>-tony
>
Received on Tue Nov 16 2004 - 19:57:52 GMT