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Topic: load cell ( tal221 ) and amplifier ( hx711) alternate implementation help (Read 49 times) previous topic - next topic


To better give a context, here is where I'm at :

I have a Sr Design project that I need to implement load cells, and realistically I need to implement a simple way for non engineering personnel to tare the scale. I have attached a picture of the 3D printed assembly with load cells. The combinator is located in the middle of the assembly, and is wired to the amplifier external to the assembly.  Each load cell (I'm using 4 load cells,  straight bar 500g tal221 http://www.htc-sensor.com/products/140.html ) the data sheet states: consists of 2 sets of 2 of strain gauges on opposite sides of the beam. These (4 in total per load cell) strain gauges form a bridge on each unit. On a higher (collection of sensor) level, The  4 sensors form a secondary bridge (please correct me if I'm wrong). These are each wired to a combinator board (https://www.sparkfun.com/products/13878). This board has a 5 pin interface with the amplifier (hx711 datasheet https://cdn.sparkfun.com/datasheets/Sensors/ForceFlex/hx711_english.pdf) which then interfaces with the micro controller.

This implementation will absolutely be subject to changes in temperature and humidity. From what I read, the repeatability of these sensors is sub optimal. I have read about every thread so far on the use of this combinator/amplifer combination, but very little GOOD information exists about the implementation of this specific line of load cells.

I do have 2 separate amplifiers and combinator boards (originally purchases as backups). I was thinking, if I can find a way to connect each set of 2 oppositely (Across each support "beam") mounted sensors to an amplifier, I can code a process that enable a multiplier coefficient for both perpendicular "X and Y" set of load cells. This I believe would improve the reliability of the system as a whole. As I understand it however, this amplifier is intended to receive an input from a bridge arrangement of the 4 sensors together ( currently what I have wired) .

Does anyone have ANY experience implementing load cells in an alternate way OR any experience with either the tal221 load cell, combinator, or hx711 amplifier?  Any input you have to the feasibility of this idea or implementation of the sensors in a functioning device would be very much appreciated.

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