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 conventional slow-moving circuit uses incandescent light bulbs, but can be changed to use...
This TTL dice is from an old publication from 1978, but it can still be assembled, as the...
The purpose of this circuit is to control magnetic door locks activated by the power grid. The...