Found in a 1970 American publication, this circuit uses transistors of the time. These transistors may be replaced by current equivalents. The factor Q is greater than 3 000.
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...