12/14/2023 0 Comments Lm339 battery level indicator![]() This resistor is called a pull-up resistor. Then how to make the output end of LM339 have high and low-level changes? In specific use, an appropriate resistance is generally added between the output terminal and the positive power supply. In addition, LEDs can be driven directly. When the negative input is 10mV higher than the positive input, its output is low.When the positive input terminal is 10mV higher than the negative input terminal, its output terminal is high.As long as the potential difference between the positive and negative input terminals is 10mV, the output terminal can be reliably switched from one state to another. The main circuit of the water level gauge is composed of 4 LM339 voltage comparators, This kind of integrated circuit has the characteristics of easy purchase, low price, single power supply operation, and wide differential range.Įach LM339 has 4 independent voltage comparators (15 in this design). After more than two years of operation, its performance has been stable and reliable, achieving the expected results. ![]() How simple is it? Only two wires need to be connected from the reservoir to the pump room. This not only eliminates the pain of often changing electrodes but also simple and easy. For this reason, this blog uses an LM339 voltage comparator to make water level gauge, ![]() However, due to electric corrosion, the function of the electrode is lost soon after use. In the past, electrodes such as copper rods or stainless steel were used to detect the water level of the pool. In this way, the pump worker must know the water level of the reservoir at any time in the pump room. IV Device selection and Component Productionĭue to insufficient water supply in some residential areas, pump workers must first store water in the reservoir and then supply water in a regular manner. Therefore, under its drive, LED can not only emit light but also achieve the effect of indicating the water level. The direction of current is what decides, all measurements are relative.This blog mainly discusses and solves the following problem: How to use an LM339 voltage comparator to make a reservoir water level gauge?Īccording to water level, this design performs signal processing and controls the potential of multiple voltage comparators, so the output will change accordingly. Also on a dual supply 0V is more dominant or positive compared with -12V, even though it appears -12V is a big number. But only spec current can be switched, do not compare with electrical switch ‘ON’. But if ‘-’ is more dominant the output transistor of comparator goes low impedance or saturates or turns ‘ON’. If ‘+’ pin is more positive than ‘-’, or is ‘+’ is more dominant, then output goes floating ‘open collector’, so No LED light. The comparator compares the battery sample voltage to the fixed reference step. This circuit is similar to Audio Level meter or VU meter circuit.īattery Charger and Rechargeable Batteries Then an attenuator obtains 1.2, 1.4, 1.6, 1.8 V steps for each comparator. R10-D1 forms the 5V reference for comparators. R15 is a part of an attenuator for obtaining ranges. R16 a 5W ceramic wire wound bleeder or dummy load. The load below is a 100 ohms wire-wound fusible ceramic resistor which will heat a bit when you test 12V batteries. Apply a dummy load to bleed the battery a bit so that proper readings can be taken on Load. When you measure the open circuit voltage of a battery with a high impedance DMM (10M), the value may be a bit misleading. The circuit is an untested design but it should work. LM339 can work on single or dual supplies, it has a open collector output that can drive 15mA, low power consumption. During off-time cap will discharge.ĭescription - This circuit uses a LM339, a quad comparator. ![]() The duty cycle of 555 can be 10% on time. A 555 Timer can turn on NPN for a sec and measure battery voltage as soon as NPN is on. You can also create an electronic load using a “NPN transistor and Electrolytic cap” with bleeding or discharge resistor. ![]() Using rechargeable batteries are good for the environment. It is important to avoid overcharge or deep discharge of rechargeable batteries. This circuit has four LEDs to show the charge left. Battery level voltage measurement is best done with a dummy load. ![]()
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