This is the battery indicator module I made by myself. It took a few hours to detect the battery of the mobile phone. I used it to detect the battery of my flashlight and the power indicator of the mobile power supply. I used the LM342 as an operational amplifier (four-level operation). Therefore, there will be four lights) Use TL431 as the reference voltage. The reason for combining a lot of resistors is because the merchant gave me the wrong resistor. He originally wanted 10K and gave 100K, so he couldn’t take 10 100K in parallel to get 10K.
When the voltage is greater than 4.09V, it means full power, because the nominal 3.6V full charge of the mobile phone battery is 4.2V 3.6V has been discharged (the picture has been processed, a bit blurry, because it was too dark when shooting)
Turn off the first light when the voltage is lower than 3.95 or so
When the voltage is lower than 3.8, extinguish the two lights, which means that half of the electricity is used.
When 3.62V is used, there is one light left, which means that the battery is almost out of power, and it is about to be charged. When all the lights are off, it means that the battery is out of power.
At the end, I helped him put on a shell (the yellow one). Can it still look good?
The circuit diagram is here (I use all pin components, which can be soldered out with a universal board. If it is a patch, it will be more troublesome.
This is the pin diagram of LM324
This is the pin diagram of TL431
When this TL431 is connected to the above circuit, the reference and cathode should be connected together (because this can get a 2.5V reference voltage to power the LM324, the formula is here (Vout=(1+R1/R2) 2.5V))
), and then connected to the positive pole of the power supply through a 2.2K resistance, and the anode is grounded,
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