42 kHz oscillator (CB21805E)

This circuit was used as an eraser for old tape recorders. The circuit is from a 1960 Mullard transistor manual.

Variable Output Oscillator (CB16513E)
We found this circuit in a 1998 publication. The circuit has controls for both frequency and...
Auxiliary Telephone Bell (CB18817E)
This circuit for conventional lines was obtained in a 1996 documentation. The circuit uses common...
Capacitance Multiplier (CB16664E)
This is the conventional version of capacitance multiplier with operational amplifier that appears in...