Principle description

This suite has simple circuit and uses the LM358 chip; it's used as voltage comparator. The comparison value is set by potentiometer. When the input voltage is reduced to the set value, the transistor turns on, LED lights, the buzzer calls.

Features

The use of accumulator power causes the output voltage decreases, if the accumulator in low voltage for a long time, it will become damaged. This suite can be used of testing 9V/12V accumulator output voltage, when accumulator in low voltage/under voltage,the red indicator lights up and the buzzer calls, which realized sound-light alarm, in order to achieve mastering accumulator discharging status.

Electrical Characteristics:

Operating Voltage:9v/12v
DC Main chip:LM358
PCB size:32*26.7mm

Schematic diagram

Mechanical Drawing

Welding note

Because of putting the silk print in a wrong place when designing. "9014" is placed the S8550 transistor(the suite only has S8550 transistor,hasn't S9014 transistor), the positive and negative of buzzer is as showing :

Instructions

1.Wedding the component correctly,"IN+" and "IN-" link to the positive and negative of 8V/10.4V power

2.Adjusting the potentiometer, when LED lights up, the buzzer calls, then stop adjusting potentiometer

3.Using the "IN +" and "IN-" to link with the positive and negative of 9V / 12V power, when the voltage is lower than 8V / 10.4V,LED lights up,the buzzer calls.