This variable filter that lets frequencies from 500 Hz to 1500 Hz pass through was found in a Popular Electronics from the 90's. The operational amplifiers are the 741.
This circuit was obtained from an English magazine from 1985. It consists of a pulser that drives...
This circuit can measure the power of loads up to 1 kW and its accuracy depends on the settings and...
This circuit came out in an English magazine from 1978. The circuit generates a ladder of 128...