Zeroing problem and ratio problem

Topic Type: 
Question

I noticed sometimes when I zero the scale and have something on it that it will sometimes take a portion of that weight and zero it as well. Is that just a weird fluke or have you noticed this too? Also, I found that sometimes when the weight is shifted on the deck a little that it activates the ratioBlownOut function and it won't go away

Trenton's picture

JPL, first of all it is gratifying to me that you actually built the device from my instructions. Regarding your question, I also found the scale does not hold absolutely on 0, but I assumed it was the error inherent in the pressure transducers I used. I think my pressure transducers are 500 psi 1% FS error where maybe I should have used 300 psi to reduce the error. In actual practice by weighing cattle and then seeing the official weight at the sale barn I believe my device is accurate to about 7 lbs, but the weights on my ticket at the sale always are multiples of 5.

I don't think I've had the problem with shifting weight, but you can adjust the ratio in the function if you like. I seem to recall in course of design and testing I felt like I did revise it toward a more permissive ratio, but I suppose you could take it further based on experience.