This temperature control was found in General Electric documentation from the 90's. The circuit uses a 10k ohm NTC sensor as a sensor. The triac must be in accordance with the controlled load.
This circuit controls a relay causing it to open and close its contacts at a speed that depends on the...
This circuit is from an Electronics World of 1968. The transistors are of the time and the power...
This circuit is from a Motorola manual from the 70s. The circuit can be implemented with more...