Based on the CA3140 IC, this circuit was found in the June 1986 issue of Radio Electronics. Sensitivity adjustment is made using a trimpot in series with the sensor.
This power inverter circuit was found in Radio Electronics magazine from December 1959....
This simple pass-through circuit was obtained in an old documentation, but it is still up to date...
This circuit was released in an Electronics Newsletter from June 1995. It uses a 10-channel...