low battery indicator circuit

this is a very usefull circuit if you're building projects powered by batteries.this simple circuit informs you when the battery needs to be recharged by turning on a led.the threshold is set to the desired voltage by a multiturn potentiometer.
the only thing you should have in mind is that it doesnt work with red led's,at least with the ones i tryied. i think it has something to do with the very low voltage that red led's need to lit.didnt have the time to experiment further.besides that,the circuit works perfect.

components needed:
R1= 1k (2,2k if you use smd led)
R2= 2.2K
U2= TL431 adjustable shunt regulator(can be found very easy in power supplies)
PR1=10K potentiometer (for higher precision use multiturn) 
LED1= led (not red-didnt work with me)


here is a video building it.





Comments

  1. Simple and very useful solution, thanks.

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  2. maybe we can substitute a piezo buzzer for the LED.

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  3. maybe we can substitute led with piezo buzzer.

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  4. hi is it possible to use this circuit for the 12v battery ?

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  5. what is the power consumption of this circuit sir?

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