Two-input amplifier (CB21661E)

The critical component of this 1967 amplifier is the driver transformer. The circuit has both high and low impedance input.

2 to 9 kHz PLL Synthesizer (CB4566E)
We found this circuit at Modern Electronics in January 1991. The magazine no longer exists, but...
Bidirectional switch (CB9162E)
Found in a 90's EDN, this circuit can be used as a shield. The components depend on the MOSFETs...
Cooking Timer (CB18596E)
This circuit will trigger an audible warning signal after the end of the pre-programmed timing. Using...