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.
The integrated circuit used in this project is not common today, but it can be implemented with more...
Found in an American publication from 1969, this circuit can be adapted to be used as a shield....
This current meter with many scales was found in a 80s American documentation. The operational amplifier...