This circuit is from an old American documentation using as indicators for the flip-flops neon lamps. This way, the circuit has two supply voltages.
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...