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LM3914 battery level Indicator ? Answered

https://www.instructables.com/community/LM3914-Battery-Level-Montitor/     I am trying to make a Battery Level Indicator using the LM3914 IC. The problem I am facing is... where you see those 3 LED's my voltage increases on the pot, where as when the LED's are all the way on it decrease across the pot. I am using a 9V Battery where I want the red led to show depletion  of battery life around 5 or so volts  how can I achieve this. Can someone please help me with this?      Which pin can I set to 5v and how?

Tags:LM3914

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iceng

3 years ago

You cannot use the LM314 to measure its own voltage.

You can run the LM314 on a second 9v battery and measure the change of that first battery.

If you want to measure 9 to 5 volts and power the instrument with the same changing supply .... Use a 3.3 volt micro processor running off a regulator that accepts 9v or 5v or 35v and regulates an uninterrupted 3.3v for the uP .... Then it is a simple matter of using a quad Op-Amp or the ADC on the uP to light the three LEDs as you like.

GREEN 9.9-7.51volts___ YELLOW 7.5-5.01volts___RED 5-4volts.

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steveastroukiceng

Answer 3 years ago

yes you can. You need the reference volts to be a fraction of the rail

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dominick.j.pezza

3 years ago

I just test my method and it works. the problem is that I could not tell where the voltage was at 5 out of ten leds lit

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dominick.j.pezza

3 years ago

I now know why I canot find the solution to the problem its due to me not having a digital votage reference, to put onto the breadboard that way I can see what resistors I need for a 5v voltage

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rickharris

3 years ago

The 3914 drives the LEDS - alter the order you connect them to the pins of the 3914.

In your case this will mean connecting to the bar graph with wires rather then direct through the bread board.

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dominick.j.pezza

3 years ago

this is what I came up with/ also tutroials that I just don't understand

ddd.png
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rickharris

3 years ago

Can we have a circuit diagram for what your trying to do please.