This rapid response amplifier uses an integrated one that is not common today but can be implemented with modern equivalents. The circuit is from an 80's manufacturer documentation.
This oscillator takes advantage of the 2000 ohms headphone inductance as the oscillator circuit coil....
This circuit, in addition to providing an output that corresponds to the absolute value of the...
This circuit works with the previous two by demodulating the signals received modulated in FM. The...