Olin Lathrop wrote: > > The FORCE on the faces of the piezo is directly related > > to the voltage across the other faces. > > Not exactly. The voltage from a piezo sensor is directly related to > the rate of change deformation. This means piezo sensors are useless > for measuring static or absolute forces. Not quite. The amount of charge movement is proportional to the force. The amount of current is proprotional to the rate of change. If you had a very high impedance input buffer, the voltage across the piezo would be proportional to the force. However, if you run the current through an external load resistance, the voltage you see there is proportional to the rate of change. Think about the reverse: If you apply a DC voltage, you get a constant change in force/shape of the piezo. Anyway, to answer the OP's question, there are many varieties of strain gauge based load cells that meet his dimensional requirements. A quick search should turn up several. They can't be too expensive if they're used in kitchen and bathroom scales. -- Dave Tweed -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu