Finally got to take a look at a thermocouple gas valve -- I've always maintained they were impossible, and I was right! First of all, I had the impression that they would open the valve (which I flat wouldn't believe) but in fact they only hold it open after you pusha da but. This one came from a water heater, RobertShaw control. There's a sheet metal U with *six* turns of looks like #20 enamel on each vertical leg. The valve stem has a washer on the end that completes the magnetic circuit. Takes about 125 ma to hold the valve open, which the thermocouple supplies at just about 2.5 millivolts giving 0.3 milliwatts. Full hot the t/c puts about 7 mv into that circuit >> ~350 ma. and 2 milliwatts. Load resistance appears to be 0.020 ohms. Talk about doing the mostest with the leastest! david David Beierl - Providence, RI '84 Westy "Dutiful Passage" '85 GL "Poor Relation" |
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