We found this multiple thermostat circuit in July 1980 Radio Electronics magazine. It uses opto-triacs for power control and operates on a 117 VAC mains.
This circuit uses a 555 (according to the diagram) to generate 50 ms tone bursts at a frequency of 1.5...
This grounding test circuit was found in an American 80's documentation. The circuit is for the...
This circuit allows frequencies between 1.8 and 30 MHz to pass. Data for the coils is provided next to...