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 circuit works with small 5 V incandescent lamps but can be modified to operate with LEDs. The...
This low power bass booster is from the 1977 National Semiconductor Audio Handbook. The circuit is...
This circuit is from an old documentation. Integrated circuit 723 is not common today. The power...