Low battery indicator (CB9133E)

This circuit was found in Maxim's documentation from the 80's. The integrated circuit is from that time, uncommon today.

Time delay (CB23969E)
This circuit turns on a lamp after the time set on the potentiometer. The circuit is from a Radio...
427 to 439 MHz booster (CB7438E)
This signal amplifier for ATV in the 427 to 439 MHz band was found in a magazine 73 for radio...
Complementary Symmetry Amplifier (CB12880E)
This amplifier has a few Watt output, using old transistors. The speaker is 45 ohms, but with...