Flip Flop 4027 (CB25120E)

This circuit was suggested by an article in the April 1988 Radio Electronics magazine. The flip-flop is of the JK type.

Bistable Multivibrator (CB9925E)
This circuit using an operational amplifier was found in old American documentation. It can be...
Simple transistor tester (CB23746E)
If the circuit oscillates, emitting sound, it is because the transistor is good. This simple...
Telephone Amplifier with TDA7052 (CB990E)
Like the previous circuit, this is used in the analog part of the telephone lines. The same...