Cable Locator (CB21303E)

This audio detector circuit can be used for cable identification. We found it in a Popular Electronics from the 90s.

Vibrato with the 555 (CB17487E)
This circuit was found in a 1986 publication. The speed of the effect is determined by the 555,...
Turntable preamplifier II (CB19173E)
This preamp version uses BC109 transistors that are older versions of the current BC549 in plastic...
VCO 555 (CB9427E)
This simple voltage-controlled oscillator generates signals from 300 Hz to 1,500 Hz with voltages from...