Ok so far I am happy with the thermostat and heating. Now comes problem 2. I want to incorporate a DC circuit to light spotlights, DC bulbs and PC fans. I ripped off the PSU of a microwave (mostly to use its transformer) and made a simple bridge rectifier. The voltage after the rectifier a schotkey type (STPS30), was 24V and I was afraid that it is too much for the input of a voltage regulator: L78512 (or L78S12). So I placed an 18V zenner diode before the input. At rest, I had a nice 18.3V input and 11.8V output. However when I connected a bulb or a fan, I had very low power :-( :-( The fan needed a finger flick to rotate a bit, and the bulb was dim.
I used R of 500Ohm. When I used 200Ohms, the resistor was a bit hot (maybe because 0.25W).
1: What is the ideal value for R? One of the fans is 0.44A, another is 0.13A (the one I Tested), while the bulb was 4W (12V) I would probably need to connect two bulbs and two fans.
What is limiting my power in this circuit????
The transformer is WDB4109 from DongGuan WanXing