This circuit was found in a 90s American publication. The same configuration appears in several places on this site, obtained from different sources. The lamps can be replaced by LEDs.
This commercial transistor radio was manufactured by RCA in the 1960s. The circuit has only 4...
This circuit has a normally low output that is triggered by a high pulse. The circuit is from...
Suggested by a 90s Popular Electronics this circuit is intended to receive volleys or whistles...