Hello,
I am interested in continuously acquiring load cell measurements with a resolution of 0.01g or lower. I need to be able to identify individual droplets of water (~0.5g) vs. time when added to the liquid container on the scale.
Naively, I bought a 1kg (0.1g resolution) pocket scale to see what kind of performance I could get. I opened it up, disconnected the four load cell leads (+/- excitation & +/- signal) from the PCB, and connected them to my amplifier/DAQ setup (excitation voltage = +/- 5V).
Scale that I used (its bridge gauge resistors are 1kOhm each):
http://www.usbalance.com/us-minibench-1000g-x-0.1g
Playing around with the filters and gain, I settled on LPF @ 5 Hz and G = 1000. This gave me roughly 2 mV/g. Unfortunately the signal (left on its own) fluctuates quite a lot with temperature/noise and drifts around at magnitudes ~10x more than the droplet signals that I am trying to measure. No good.
I am considering getting a 0.001g scale instead of this 0.1g scale, but I am wondering if these differ only in their signal processing hardware and not the actual load cell setup.
Any suggestions on a plausible way to measure these small droplets without being squashed by ambient/temperature noise?
Thank you!
***SOLVED***
Grass FT03 force-displacement transducer with syringe collector screwed into transducer arm.
I am interested in continuously acquiring load cell measurements with a resolution of 0.01g or lower. I need to be able to identify individual droplets of water (~0.5g) vs. time when added to the liquid container on the scale.
Naively, I bought a 1kg (0.1g resolution) pocket scale to see what kind of performance I could get. I opened it up, disconnected the four load cell leads (+/- excitation & +/- signal) from the PCB, and connected them to my amplifier/DAQ setup (excitation voltage = +/- 5V).
Scale that I used (its bridge gauge resistors are 1kOhm each):
http://www.usbalance.com/us-minibench-1000g-x-0.1g
Playing around with the filters and gain, I settled on LPF @ 5 Hz and G = 1000. This gave me roughly 2 mV/g. Unfortunately the signal (left on its own) fluctuates quite a lot with temperature/noise and drifts around at magnitudes ~10x more than the droplet signals that I am trying to measure. No good.
I am considering getting a 0.001g scale instead of this 0.1g scale, but I am wondering if these differ only in their signal processing hardware and not the actual load cell setup.
Any suggestions on a plausible way to measure these small droplets without being squashed by ambient/temperature noise?
Thank you!
***SOLVED***
Grass FT03 force-displacement transducer with syringe collector screwed into transducer arm.
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