Metal detector receiver (CB22457E)

Found at Popular Electronics this receiver is used with a transmitter for quadrature-coil signals.

12 V x 5 A Power Supply (CB1508E )
This traditional configuration from a simple 12 V source is from a 1977 publication. The...
LED Sequential (CB18090E)
The circuit is suitable for small animations, with the movement effect of the LEDs in a matrix...
Crystal Colpitts Oscillator (CB13853E)
This circuit is from the National Semiconductor 1977 FET Databook. The FET can be BF245 or MPF102...