This circuit for audio signals was found in the March 1990 Radio Electronics magazine. The circuit uses a unusual optocoupler that can be replaced with an equivalent one.
The circuit shown is from a 1993 documentation. It uses two FETs in an oscillating configuration that...
This output step with a transistor can be used in experimental radios and intercoms or as a signal...
This circuit, for bands above 15 MHz, was found in an Argentine publication from the 1970s. The L1...