This LED DC voltage indicator circuit is a voltmeter, rather than simply a battery tester. As such it may measure voltages as low as 3V. It utilizes venerable LM741 operational amplifiers applied as ...

Up to now, this battery level indicator design was limited to 12 & 24V applications. In past circuits, the use of fixed resistors greatly simplifies setup. However, fixed resistors resulted in ...

This overvoltage detector can be connected to any dc power source (Fig. 1). Its purpose is to provide a visual indication of when the voltage exceeds a preset value, which may range from around 3 V ...