This is an ideal circuit to monitor the Voltage level in 12 volt Lead Acid batteries used in Inverters .For the perfect operation of Inverters, the battery voltage should be between 12 and 13.5 volts. A fully charged battery shows 13.5 volts. If the voltage reduces below 10 volts, the Inverter will not give back up. Moreover, if the Inverter is continuously charging without attaining 13.5 volts, it indicates that the battery is not accepting and holding charge.

This simple water level indicator will activate a buzzer in order to make a noise when a certain level of water is being reached. Because the water sensor and the command circuit are located on the same printed circuit board, indicator, together with its 9 V battery and the buzzer can be mounted in a compact case. Obviously the sensor, that is made by corossion, on the board, must not be mounted directly on iron or steel bathtubs but with a magnet atached on the case. Check out the new water level sensor circuit.

It is an ideal solution to protect rechargeable batteries from deep discharge. It gives an LED indication when the voltage level in the battery drops below 5.1 volt.

Is is easy to test the polarity of a circuit’s point whether it is positive or negative by using the tester circuit featured here. The tester circuit has a high input impedance (around 1 megaohms) to avoid loading the point being tested. In testing sensitive points however, (inputs of opamps), the input impedance must be taken into consideration.