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LM3916 24V measurement

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oriol

New Member
Hi everyone, I bought an LM3916 device to measure a 24V battery level, but there are only example circuits for 1.2-12V signal source, so I don't know if it's posible to design a circuit to measure those 24V. could it be posible?
Thank you
 

3v0

Coop Build Coordinator
Forum Supporter
What you need is a voltage divider.


It is an easy concept to understand. Because each of R1 and R2 are identical. They each must drop 1/2 Vin.



Make R1 and R2 10K. Connect the voltage you need to measure to Vin. Connect Vout to the LM3916. When Vin is 24V Vout will be 12V.

3v0
 

oriol

New Member
yes, that's what I thought but, does it really work? I mean, does the LM3916 measure correctly the batteries state with a voltage divisor?
 

Sceadwian

Banned
Why wouldn't it? It's a 12V lead acid vs a 24V lead acid, scaled down they have the same curves.
 

crutschow

Well-Known Member
Most Helpful Member
yes, that's what I thought but, does it really work? I mean, does the LM3916 measure correctly the batteries state with a voltage divisor?
As Sceadwian stated, it will. A resistor divider is perfectly linear. Thus the LM3916 output will be a proper representation of the 24V battery voltage.

The LM3916 is designed for an audio VU meter, which has a non-linear output. If you wanted a linear representation of the voltage, you would use the LM3914.
 
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oriol

New Member
oops, yes, I thought 3916 was the linear one.... it's a logaritmic one then isn't it? I'd better use the LM3914.

Thanks
 

oriol

New Member
Is there another way to do a batteries measurement with some simple chips like LM3914? I say that because the LM3914 only goes to 5V..... and I need to measure 24V. The LM3916 goes to 12V but it's not linear
 

crutschow

Well-Known Member
Most Helpful Member
You just use a voltage divider as previously described to drop the 24V to 5V.
 
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