Signal generator (CB21057E)

Found in Popular Electronics, this '90s circuit generates harmonic-rich signals for testing audio equipment.

Geiger Counter (CB21199E)
Found in old documentation, this meter has a high voltage inverter for the Geiger tube. The...
100 kHz Operational Oscillator (CB15105E)
In the figure we have a 100 kHz crystal-controlled oscillator using an operational amplifier....
4001 Oscillator 600 Hz to 6 kHz (CB24341E)
Found in the November 1974 issue of Radio Electronics magazine, this circuit has a frequency range...