This simple step of low power audio is from a 1975 documentation. The transistor can be a BC548, and the transformer of the type found in small transistor radios and recorders of the time.
This circuit causes the relay to be energized when the input voltage exceeds the voltage value of...
The maximum frequency of this circuit is 500 kHz. We found it in a documentation for radio...
The mains cables work as antennas. We can take advantage of them with this circuit that consists of a...