This circuit provides an audible signal when testing a TTL circuit. The circuit is from an old documentation, being fed with the 5V of the circuit under test.
This circuit for VCR recording heads was found in the February 1990 issue of Radio Electronics magazine....
This very simple continuity tester uses a small 1.5 V lamp (type used in flashlights). Can be...
This commercial radio with 3 earphone listening transistors was manufactured in Japan in the...