LED Flasher Unijunction (CB22144E)

The frequency of this circuit depends on the capacitor. The unijunction transistor can be the 2N2646.

Headphone Extensions (CB23790E)
The figure shows three circuits for using headphones in amplifiers with speakers that do not have...
Nicad charger (CB9540E)
In this charger, the charging current is basically limited by the LEDs. The transformer is a low...
Fast Voltage Follower (CB4904E)
This configuration is from an old integrated circuit manual. The circuit can be applied to modern...