Long-Interval Timer

Occasionally there is a need for a timer circuit for tasks such as switching off a circuit element (such as an LC display) after a given interval or generating a time delay for an application. Short intervals can be conveniently generated using a 555 timer, but if the switch-off time lies in the range of minutes or longer, a 555 is no longer suitable due to the large value required for the capacitor, which leads to inaccuracies or instability. In such cases, a digital counter circuit with an oscillator is a better solution.