Metal detector receiver (CB22457E)

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

Phonograph Preamplifier LM381 (CIR25278E)
This preamplifier for magnetic cartridges was found in the February 1990 issue of Radio...
Simple switch with SCR (CB25059E)
This circuit is used to switch direct current loads such as a lamp, for example. Remember that...
Unijunction Triac Control (CB25861E)
This power control circuit was found in an article in the June 1995 Electronis Now magazine. The...