This circuit with current up to 100 mA according to the transformer was found in the Radio Electronics magazine of October 1991. The regulation is done directly by the zeners.
This Vox or sound activated relay was found in an American documentation from 1975. Equivalent...
This circuit is from Motorola's Linear Interface ICs from 1993. The circuit uses a booster...
The existence of field effect transistors at the input of the integrated circuit (operational...