On Mon, 25 Aug 1997 16:03:57 EDT Harold Hallikainen writes: >On Mon, 25 Aug 1997 13:24:55 -0300 Octavio Nogueira > writes: >The 5kg load cells costs me about >US$60 and I don't thing the >>spring/motion >>sensor >>could have the same precision as load cells, but if you don't need >>precision, >>it's just ok, but then you have mor mechanics to deal with. >> > > Wow! I'm surprised they're that much, though I never tried to >buy one. I have, however, bought some pressure transducers from >Motorola. As I recall, they were pretty cheap (I think under $10 US) >and included conditioning circuitry so something like 0 to 5 volts >came out. So... maybe make a scale by having a piston and cylinder >drive a pressure transducer? There's gotta be an easier way! A piston and cylinder would be hard to make as well as suffer from leakage and friction. Something like a bellows or air bag holding the load platform up might be better for a low-capacity scale. It would be very resistant to overloading, since those sensors can withstand something like 10x rated full-scale pressure. The pressure in the air system with no load on the platform would need to be positive to keep the sides of the air bag from collapsing.