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Questions &/or issues related to products in the Flex / Force category should be posted in this forum. includes Force Sensitive Resistors, Load Cells & Amplifiers, Pressure Sensors, etc
#207024
I need to measure the individual weights on each of four load cells to determine how well an object is balanced on a platform.
(I am able to use four 50kg strain gauges (SEN-10245) with the hx711 & Raspberry Pi to measure total weight.)

Questions:
1. Is it possible/practical to design a circuit to accurately measure just a single SEN-10245? I tried wiring it with two 1k resistors to form a pseudo whetstone bridge. I get readings, but not surprisingly, they are very inconsistent.
If not,
2. Any advice on finding this part or similar for a reasonable price in the US?
DYMH-106 50kg
Image
  • AliExpress in China has it for $56+shipping, but says it can't be shipped to my region.
  • Digikey has one similar for $853
  • Amazon has it for $118 each, which may be cost prohibitive
Cheers,
Jeff
#207032
Is it possible/practical to design a circuit to accurately measure just a single SEN-10245? I tried wiring it with two 1k resistors to form a pseudo whetstone bridge. I get readings, but not surprisingly, they are very inconsistent.
Usually when you see inconsistent results with a load cell, it comes back to a bad connection somewhere introducing a bit of resistance, or flux residue on your load cell connections causing a very small stray current. Make sure you've cleaned off all flux residue from your PCBs and solder all the connections for the load sensor and resistors used with the load sensor.

The only other thing to check would be to make sure you have the load sensors mounted so that the sensor is able to deform when weight is placed on them. See the photos in this post for an idea how the sensors should be mounted. There needs to be a hole or depression that allows the sensor to move a bit when under load. If they are mounted to the back of a flat board, you're not going to get accurate results.
#207033
Thanks Chris, it sounds like I may need to solder my prototype to avoid breadboard inductance noise.
The sensors are mounted over recessed holes allowing the middle bit to flex without interference.

Have you heard of anyone having success with measuring with a single Load Sensor, maybe something like this?
(edit: the Hx711 is connected on the right of the schematic)
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