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### Topic: Help with Measuring Load Cell Voltage (Read 3515 times)previous topic - next topic

#### rpmaurer

##### Nov 03, 2012, 04:09 am
Shouldnt be too hard, only problem is that the loadcells can out out up to 8.8v... too high for the Analog pins i think.  How can I turn the 8.8v into 5v?  Resistor?  I would prefer not to have to completely redesign the load cell setup to run on 5v

Ryan

#### retrolefty

#1
##### Nov 03, 2012, 04:22 am

Shouldnt be too hard, only problem is that the loadcells can out out up to 8.8v... too high for the Analog pins i think.  How can I turn the 8.8v into 5v?  Resistor?  I would prefer not to have to completely redesign the load cell setup to run on 5v

Ryan

Can you provide a link to your load cell device? Most we see are very low voltage output devices, millivolt outputs usually requiring a op-amp to interface usefully to an arduino. So any advice we could give should be in context with a datasheet based on your specific load cell.

If indeed your device outputs a 0 to +8.8vdc measurement signal, a simple two resistor voltage divider using a divide by 2 ratio (two 5k ohm resistors in series should work fine) would work easily for an arduino analog input pin.

Lefty

#### wwbrown

#2
##### Nov 03, 2012, 04:33 am
Listen to Lefty he is making good sense, pat manufactures  and numbers and a schematic would help,

#### rpmaurer

#3
##### Nov 04, 2012, 01:40 pm
It is an Aerocon Load Cell, used for Testing rocket motors with forces of up to 220lb.  And yes it does output in millivolts, my amplifier that I made hoever puts it up to 8.8v

#### wwbrown

#4
##### Nov 04, 2012, 05:29 pm
For load cells I have good luck with simple instrumentation amps like TI's INA122's powered off the 5 V line from Arduino, the output on it is 0 - 5V.  In your case I would check if you can operate your amp with a lower voltage so your output does not exceed 5 V.  Alternatively, you could probably use a simple voltage divider with two resistors.

#### MarkT

#5
##### Nov 15, 2012, 01:18 pm

It is an Aerocon Load Cell, used for Testing rocket motors with forces of up to 220lb.  And yes it does output in millivolts, my amplifier that I made hoever puts it up to 8.8v

Can we have links to datasheets for both the load cell and the amplifier please?
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

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