Found in Electronics now from the 90s, this circuit uses a sensor from the time, which is difficult to find today. The circuit activates a sonalert-type buzzer.
This power supply circuit was obtained from the February 1993 Radio Electronics magazine. The...
This circuit multiplies the frequency of a signal by 100. The circuit was found in the October 1994...
This is the receiver for the previous circuit we found in the December 1992 Radio Electronics...