This proximity sensor was found in a 90s Popular Electronics. The base is a PLL567 that operates at around 100 kHz. The circuit operates by capacitance sensing.
This circuit uses an ignition coil to generate the high voltage that electrifies a fence. However, in...
This circuit, which was common at the time, was found in the February 1973 issue of Radio...
Using the LM317 (or LM350), this circuit is based on precision regulatory components such as those...