This circuit was found in 1960s Radio Electronics. The circuit uses components from that time. The triac is according to the controlled load. The sensor is a common LDR.
This simple thermostat circuit was found in the September 1976 issue of Radio Electronics...
We found this circuit in the 1982 SGS Linear Integrated Circuits manual. The integrated circuit used...
This circuit uses a FET to drive an LED with constante currente. The current up to 20 mA can be...