This circuit was found in an American documentation from the 90's. It switches a continuous voltage obtaining an AC voltage at the output of approximately 1 kHz.
This circuit sensor is an NTC with a resistance of the order of 2k. The SCR can be from the TIC...
The load current can be adjusted up to about 1 A. The transistor can be TIP32 or TIP42. The...
This oscillator with common general-purpose transistors appeared in Radio Electronics magazine in...