This simple continuity tester, whose configuration can be found several times on this site, is powered by only 2 batteries providing the indication on an LED.
The integrated circuit used in this 1986 project is not very common today. The circuit uses few...
This circuit controls a relay causing it to open and close its contacts at a speed that depends on the...
The circuit is from the MC1539 manual, an operational one close to the 741. The transistor admits...