This circuit was found in a 1966 General Electric book. The triac and the day are from that time and can be replaced by modern equivalents depending on the load.
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...