This SCR relaxation oscillator was found in an 80's Electronic Design. It flashes a small incandescent lamp in frequency that depends on the capacitor.
Suggested by Texas Instruments in 1980s documentation, this circuit uses a component of the era....
The idea of this simple circuit is to use a tape recorder to key a transmitter in code emission....
This relay circuit with a dual channel MOSFET (not very common today) was found in an old American...