Obtained from a 1969 documentation, this circuit can operate at frequencies up to 500 Hz, counting up to 999. The circuit makes use of neon lamps of the time.
In the figure we have a Texas Instruments circuit for TTL interfacing using discrete transistors. The two...
This circuit was found in Radio Electronics magazine from June 1963. The range is small and the...
The project presented in a 2009 documentation is intended for radio amateurs operating in the...