Introduction
This circuit was designed to work with the Battery Charger circuit. It monitors the battery voltage level so when it goes below a preset level it can either disconnect the load or send an alarm.
Description
The LM393 consists of two independent precision voltage comparators. Pin 2 is the reference voltage and pin 3 monitors the battery level. By adjusting the value of the 3K3 resistor, the voltage level can be adjusted higher of lower. At the moment it is set for approximately 10.5v.
While the voltage at pin 3 is above that of pin 2, the output of pin 1 is an open circuit. When the voltage level at pin 3 drops below that of pin 2, the output of pin 1 is now ground. By altering the zener voltage and 3K3, lower or higher voltage levels can be monitored.
Features
The LM393 has a wide single voltage range of 2.0 to 36 Vdc or dual supplies of +/- 1.0 to +/- 18 Vdc. It also has a very low voltage drain of 0.8ma, low input biasing current of 25ma. The output voltage is compatible with TTL, DTL, ECL, MOS and CMOS logic systems.