This circuit was found in the July 1988 issue of Radio Electronics magazine. It makes use of an operational transconductance amplifier (OTA) still in use today.
Found in a 90s Popular Electronics, this touch switch uses a single sensor. PLLs are common today....
We found this circuit in an old documentation from 1979. It is a logic level tester that is...
This ultrasonic insect repellent was found in American documentation from the 1980s. The...