TTL Counter (CB21360E)

This counter from 0 to 9999 was found in English documentation. The power source must be 5V with at least 1A.

Circuit with space mark 555 (CB24845E)
Found in September 1984 Radio Electronics issue this circuit has adjustable pulse width and...
Tunnel Diode Listening Transmitter III (CB19427E)
This low power circuit for the FM band was found in a spy book from the 90s. The tunnel diode is...
Touch On OffSwitch (CB10233E)
This circuit was found in a 1987 edition of the United States' Hands On Electronics magazine. The...