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Re: [Phys-L] Sonometer, What Do You Think of the PASCO Model?




On 2014, Jul 29, , at 17:26, John Denker <jsd@av8n.com> wrote:

On 07/29/2014 04:00 PM, Bill Norwood wrote:

- Has anyone considered the bass guitar with 4 tensile strain gauges just
past a "frictionless" bridge on the tuning end?

They have now.

- I have no idea of the dimensions of, or how to shop for, such strain
gauges.

I suspect you want to measure force i.e. stress, not strain.
The magic word here is "load cell".
Once you know the magic word, the shopping becomes easy.
Use "google shopping" (as opposed to regular google web search):
https://www.google.com/search?q=%22load+cell%22&tbm=shop


Making a load cell from a resistance module was one of the exercises at a recent Vernier engineering workshop. (or was it calibrating?)

I thought such measured the resistance due to the strain experience by a resistor.*** e.g. pencil lead on paper. The stress is inferred by the spring constant.

One use early in UCSC’s history was a resistance module glued to an Al rod. It detected a sound pulse. (At least that’s my interpretation of a bunch of them surplussed back before 1984.)

The load cell (force transducer) Vernier cells is too big for a string instrument, but would work (unnecessary) on a sonometer.


*** an early version used a plate w/ a magnet and a Hall detector, IIRC!


bc, may be engaging in his favo. occupation.***

***Jumping to false conclusions.