force sensor...

[Andrew W. Macfadyen]

The only really viable option is a strain gauges either applied directly to
some part of the reaction mountings of the brake or in the form of separate
load cell.   The simplest application is too mount the strain gauges on the
upper and lower surfaces of a beam (bar) in plain bending, as most dyno
usually have a reaction bar which was connected to the traditional spring
balance this would be the ideal arrangement.
Temperature compensation is achieved by mounting 4 strain gauges in a
Wheatstone Bridge arrangement, with the gauge in tension in the diagonally
position from that in compression, the other 2 gauges are dummies for
temperature compensation mounted on an unstressed part of the structure.
Add a constant voltage source and an instrumentation grade  OP amp such as
an AD622N and you have your sensor.
I have designed a couple of load cells for industrial robots using wire
strain gauges and can assure that these will give highly accurate repeatable
results.

Daniel R. Henriksson wrote:

> I recently acuired a water-brake dynamometer.
> I'm now looking for some force sensing device, to use as a torque-meter,
> it should be a robust temp compensated one, drag or pull doesn't matter.
> It should have a voltage or PWM output.
>
> Any ideas?
>
> Finally i can make some serius mapping of my home efi... ;-)
>
> /Daniel