# Measuring wire tension with a galvanometer

1. Nov 16, 2005

### EnhancedMonkey

Hello all. I would like to measure the tension on a very thin magnet wire and I have read about people making scales with a galvanometer (voltmeter). Basically, instead of using the meter to measure current, you send current thru the galvanometer and use the needle to exert force on an object. The current required to exert force and the force exerted are supposed to be linear. I was thinking a wheatstone bridge type setup. I am looking to measure in the neighborhood of 5-15 grams. I don't think I'd be able to generate this much force with a regular old analog meter, but I was curious if anyone knows what kind of actuator they use in seismic and polygraph plotters. This would probably be suitable.
I was also looking at strain gages to measure wire tension.
Does anyone have experience in this area? Which route should I go? Does anyone have a better idea?
Any help would be greatly appreciated!................D

2. Nov 16, 2005

### brewnog

I quite like the sound of the galvanometer technique to be honest, it seems a rather sweet way to do it, if it works! How much do you expect the middle of the wire to deflect by with a load of 5-15 grams?

For the boring solution, is there any reason you can't just strain gauge something between one of the wire ends and its anchor?

3. Nov 16, 2005

### EnhancedMonkey

I like the galvanometer solution myself - the only reason I'm not using a strain gage is because I'd have to order it by mail and they're \$50 for a minimum of five. Basically, I am a immediate satisfaction kind of guy and I'm cheap.
That's another thing I need help on...
How much will it deflect? What I'm really doing is using a tensioner on one end and pulling the other end until it starts to slip through the tensioner. I guess you would say that I'm measuring the start-friction of the tensioner. I don't know how to figure out how much the deflection is - I would imagine it would be some vector quantity.
...Maybe I should just give in and pay the fifty bucks.
.........D