This circuit activates a horn from an audio signal. This can be used for remote control via audio signals. The circuit is from a Radio Electronics from October 1965.
Being able to operate with frequencies up to 100 kHz, this circuit was found in a 90’s...
The integrated circuit used in this filter is not very common today, but the reader can use...
This circuit doubles the frequency of signals from 10 to 50 MHz. We found it in a 1969 Electronic...