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 is from a Linear Technology integrated circuit manual from the 1990s. The circuit...
The IC used in this project is not common these days, but if you have one you can build a high...
With this circuit, it is possible to excite a white LED or another type of high brightness with...