Model 152 PSU dummy loads - Re: NeXT Cube - powers on briefly then off again

Tapley, Mark mtapley at
Mon Oct 26 10:21:24 CDT 2015

On Oct 26, 2015, at 10:09 AM, Paul Koning <paulkoning at> wrote:

>> I concur. Tap water may have contaminants (such as chlorine) that will cause electrical leakage.
> Sure, but so what?  A dummy load is supposed to have electrical leakage.  All that water contamination would do is reduce the effective resistance of your load by a hair.

	OK, so a couple years back, I wanted to have some chemistry fun with the kids. So, I got out the jump cables, clamped them onto some aluminum foil, stuffed the foil into test tubes, filled the tubes with water, inverted both of them in the same basin and sprinkled in a little salt, cranked up the car, and sure enough … bubbles started evolving off the foil and collecting in the test tubes. 
	Just as expected, one tube was filling with gas twice as fast as the other. 
	Just as expected, when we held that tube over a candle, it went “WHEEP” and got hot (the flame was barely visible). 

	Um… the OP had a 12V supply, right? How *do* you keep from electrolyzing your coolant in this apparatus?
														- Mark

PS. this is a cool experiment but suitable cautions apply. The most subtle is: not too much salt, lest you start evolving chlorine gas instead of hydrogen. Flammable to explosive gasses, 12V sparks, etc. etc… be careful if you try to replicate this.

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