/diy/ - Do It Yourself

>>1710043
So does anyone know anything about strain gauges? I watched a few youtube videos and it seems like at least some of the (cheaper) bathroom scales have just one gauge that looks something like this. These can be fairly expensive even on ali express (up to $20 for a 200kg gauge) But those ratings are probably fake (just like their 6000mah batteries). I have no idea if I could get away with using just one or I need at least 2 or even 4. There are super cheap ones 50kgx4 that only cost like 2 dollars which is clearly too good to be true. There are half-bridge 1/4 bridge and full bridge configurations.
The idea is to mount them underneath the weight rack so they will be under a constant load of at least 70lbs (the rack itself plus the empty bar since the bar does count!)
I am thinking I don't need much accuracy since the weights are fixed so I'd be adding them in discrete increments of +20 + 10 + 5 etc. So 10% accuracy should be enough to tell 20lbs from 15lbs (but it is kinda close).