This 1988 circuit makes a back-and-forth of LEDs whose speed is controlled by P1. All components used are common and the circuit can be powered by voltages from 6 to 9 V.
This interesting circuit measures the distortion of the sinusoidal voltage of the power grid. We...
The operational amplifier used in this old application is not common today, but more modern...
Used in 1950s CW receivers, this type of circuit used germanium transistors. The circuit has...