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.
I found this circuit in a 1992 Electronics Experimenter Handbook. The circuit can be easily...
Found in the February 1990 Radio Electronics issue, this sophisticated 100 MHz probe uses a period...
Found in 90s Popular Electronics, this circuit fires a load through a MOSFET from an audio signal...