This circuit activates a relay when the supply voltage drops below the value set in the trimpot. The transistors can be the BC548 and BC558 and the 6 V relay. The circuit was found in a 1999 Poptronics.
The CMOS 4046 integrated circuit is not very common today, consisting of a very efficient PLL for...
This circuit is from an English publication from 1979. It describes the assembly of a sensitive touch...
This simple optical alarm circuit was found in the 1991 Electronics Experimenter Handbook. The...