vividvilla
Junior Member level 3
A Simple add-on circuit that can be connected to most occasionally used 9V battery-powered equipment to give a low battery warning is shown in Fig.. It is simply connected to the circuit so that it is powered up when the main circuit is turned on. With a new battery, the l.e.d. D1 should light briefly. This period will get progressively longer until the l.e.d. fails to extinguish, which shows that the battery needs replacement. The circuit therefore doubles as a power-on indication to show that there is a battery fitted.
Get Low battery Indicator Circuit
Get Low battery Indicator Circuit