PTT or Push to Talk is the control that switches the speak-hear function on a transceiver. This circuit was found in the magazine of radio amateurs 73, in an edition of the 90s.
Using the 555 and 7400 this circuit was found in the September 1977 Radio Electronics magazine. The...
This sensitive continuity test uses two transistors and has a common LED as indicator. The input...
This circuit appeared in a noverber 1962s Practical Electronics. The magazine is no more, but the...