This alarm goes off if someone leaves a door open. We found it in the Encyclopedia of Electronic Circuits Volume 5 from 1995. The circuit uses components that are still common today.
This gun-like sound effects circuit is based on the PLL4066. The circuit was found in the December...
The output current of this circuit reaches 12 mA. The zener diode determines the output voltage. The...
The circuit shown in the figure can serve as a basis for frequency meters, clocks. Stopwatches and many other...