Using the CA3140 integrated circuit, this switch was found in the June 1986 Radio Electronics magazine. Sensitivity adjustment is made at the trimpot in series with the sensor.
What differentiates this circuit from the previous one (CB12689E) is the non-need to use a...
This circuit uses only one transistor and has an excellent gain for the type of signal source...
The circuit shown in the figure causes a piezoelectric transducer to emit interval beeps. The 100...