Connecting two load cells together

Discussion in 'The Projects Forum' started by Vidula, Nov 28, 2016.

  1. Vidula

    Thread Starter New Member

    Jul 18, 2016
    2
    0
    Hi,
    I am designing a ble based weighing product.This product has two load cells and the final weight is the average of weight measured by these two load cells. My issue is if i will use two load cells individually then the circuits consumes high current (5mA continuous) which is not good as i am using only one cr2032 to power entire circuitry. So i was thinking to connect these load cells such way that they will act as a single load cell somewhat like 3 wire load cells connected in bathroom scales.
    I want to connect my load cells such way that the effective resistance will be low and hence low current consumption. effective resistance of 1 load cell is 1k.
    Kindly guide me on this,your feedback is important.

    Thanks in advance!
     
  2. JohnInTX

    Moderator

    Jun 26, 2012
    3,340
    1,671
    Consider switching the excitation power to each load cell. Turn on only as long as it takes to do the measurement e.g. one ADC conversion then turn it off. You'll want to average the readings so repeat: On-convert-off-calculate-delay and repeat as necessary. With no weight on the scale, you can sample infrequently with one cell until you detect weight applied then turn the other on and sample more frequently.

    No matter how you wire 1K loadcells, you're going to have to switch the power to the cells and likely take other measures like sleeping the processor between readings to make a 2032 work for any reasonable time.

    Good luck!
     
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