Insect repellent (CB8102E)

This circuit was found in a PE Hobbyst Handbook from 1992. The second oscillator is a VFO. The integrated circuit is a double 555 of the time.

Tuned optical sensor (CB7246E)
This 1967 Philips circuit recognizes a light signal (visible or infrared) modulated by tone. The...
Automatic Telephone Recorder (CB5992E)
This circuit turns on an old cassette recorder when the telephone rings, thus enabling the...
Power Grid Data Receiver (CB4810E)
This is the receiver for the previous circuit transmitter. Similarly, no information about the...