This circuit was found in a Popular Electronics from the 90's. The CMOS integrated circuit used is not very common nowadays. The range depends on the infrared LEDs. R7 can be changed.
March 2017 - The integrated circuit division of IXYS is presented the integrated relay that makes...
This circuit is from the time when cars used contact breakers. This 80's version measures the dwell...
We found this circuit in the Radio Electronics magazine of January 1986. The frequency is given by the...