This simple metronome, from 1985 documentation uses only transistors and has two settings. For voltages above 6 V, up to 12 V, replace the BC557 with a BD136.
Found in Popular Electronics from the 90s, this signal tracer or tracer can be used with the inner...
This circuit is from a Hughes documentation from 1968. The components are of the time and the RC...
This circuit was published in an English magazine from 1980. The magazine no longer exists, but...