This two-transistor circuit was found in the September 1971 issue of Radio Electronics magazine. The sensor is an NTC and sensitivity adjustment is via R1.
Found in 1967 General Electric documentation this circuit uses a PUT and a diac to generate 1 kHz...
We found this circuit in documentation from Linear Technology of the 80s. The circuit uses...
This 800 Hz sinusoidal oscillator was found in a 1970s American documentation. The transistor...