This amplified metronome was found in a 90s Popular Electronics. The circuit is powered by a 9 V battery but will also work with 6 V of 4 standard batteries.
16 commercial test circuit for tubes and transistors appeared in Radio Electronics magazine in...
Suggested by an American publication, this circuit has 5 operating conditions indicated in the...
This circuit with an integrated circuit of the time was found in the magazine Radio Electronics of April...