A thermistor, if memory serves. (I may be wrong---I am not an electronics guru.)spro wrote:Altogether fine. I don't know what amps or much about anything there. There are these little fuse things which can be obtained for different temperature. They would be in series but with 120 or 250 v they break with heat. You can determine max heat temp and they will blow like a fuse. I've looked at them and there are many between 160f and 260f. Not to make it more difficult but something to consider when things get too hot yet don't trip a breaker.
In this case, I expect one is not required, as the amount of heat generated is quite low. The circuit breaker is rated below the output rating of the transformer, so it would trip before the transformer managed to overheat. If the primary shorted, the main breaker would trip. I think I'm covered. The bridge rectifier is rated for 35 amps, and is mounted on a heat sink. Considering it sees only about 3½ amps, I expect it won't create much heat, nor will the transformer, which is being called upon to produce only half its rated output. All in all, I'm quite pleased with the results.
The two supplies provided by hammermill have all kinds of safety devices built in, as they were made to be used in commercial low voltage lighting. If they were just as quiet as the one I built!
Harold