This circuit is from a 1968 Electronic Design. The components are from the era and the operating frequency is 60 MHz. No data on the coils is provided.
This 1967 Philips circuit recognizes a light signal (visible or infrared) modulated by tone. The...
This circuit turns on an old cassette recorder when the telephone rings, thus enabling the...
This is the receiver for the previous circuit transmitter. Similarly, no information about the...