This counter was found in the November 19983 issue of Radio Electronics magazine. The power supply can be between 3 and 12 V typically. The counting speed depends on C1.
This circuit generates a high negative voltage responsible to produce ions in a tip electrode. The circuit...
This photo-relay uses a Darlington stage to increase sensivity. Any photo-transistor can be used....
This circuit for alternating current loads has a built-in timer. SCR2 is according to the motor...