OT - Electronic Scales
Turbo Mini Forums

This is very off topic, how do electronic scales work? is there some kind of electronic component which can sence weight?

Team Racing

Its called a strain gauge.

http://en.wikipedia.org/wiki/Strain_gauge

Day time job not paying well Jim?

In the 13's at last!.. Just

losing weight ready for Avon, every shit counts!

lol, no I was looking into making some corner weight scales, but with the cost of load cells and strain gauges I don't think it's any cheaper than buying them.

Thanks for the info colin, gave me the head start I needed.

Team Racing

I have a strain gauge,

I keep it in the bog.

surely with all the fat bastards in america you could import 4 heavy duty sets of bathroom scales lol

lol, I have actually thought about that turboman:)

Edited by Sprocket on 3rd Apr, 2008.

how many kilos are needed for a scale underneath the front wheels on a mini?

im thinking about 175, just shy of 28 stone lol

the miglias are often around 230kgs on the front corners and around 100 kgs on the rear (wet with driver)

Team Racing

damn it, can only find up to 200kg bathroom scales lol

okay, then you cant get large enough scales on ebay usa even:) one could just buy 6 cheapo scales, and use two on each front wheel and one on each wheel at the rear?

i use bathroom scales 4 on the front 2 on the back
just put a piece of wood bridging the front ones

IKEA have VERY cheap scales that do the trick!

//marcus

internationally known as "big" swede

yes thats what I spotted actually! with 4 scales on the front there is a total capasity of 480 kg. It is possibly also possible to overload them slightly...? they where only about 5 quid each:)

I have looked into this also. I took apart a set of bathroom scales and although there is a strain gauge it is difficult to isolate the gain circuit from the board. Howeve if you are not that bothered about it being accurate I reckon that the electronics will only set you back £80 to £100 in parts, but making the mechanical bits is not cheap either. I will dig out what I looked at last time.

http://www.twin-turbo.co.uk
http://www.hillclimbandsprint.co.uk/default.asp

A man without a project is like a like a woman without a shopping list.

you dont fancy what I plan and G13B does Ben? I am all ears.

internationally known as "big" swede

OK, I have done a bit more research. I can't for the life of me find any prices for a foil strain guage, but a siple amp for each gauge will be about £7. Couple this to a simple pic controller and a simple display, a few buttons and a box and you have a cost of about £40.

(Details of the amp http://focus.ti.com/lit/ds/symlink/ina125.pdf)

If I can get a price for the foil strain gauge its self then I can a better idea of cost.

I think you may need a little more money to get some cables and connectors etc.

Now for the pads. These should be quite simple to make. All you need is a pad that deflects a piece of metal that the strain gauge is bonded to. Check out page 3 of this for an idea of how to do it. http://www.sensors-uk-transducers-instrume...ndy%20Scale.pdf

Alternatively, get some cheap electronic bathroom scales rip out the electronics leaving the straingauge. Hook that upto the amp and hope that it is only health and safety limiting the weight!

The cheapest way is make one gauge then all you need is the amp and a simple circuit to display the weight and for calibration, again a pic controller is the easiest way. The make 3 blocks the same size as the pad (scales) and you can measure each corner individually.

If I find cheap set of scales I might give this a go.

Ben

http://www.twin-turbo.co.uk
http://www.hillclimbandsprint.co.uk/default.asp

A man without a project is like a like a woman without a shopping list.

few chaps on the 16vminiclub have done the 4 skales on teh front and 2 on the rear trick. using argos's finest you can do it pretty cheap.

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Hi,
I've been using Argos kitchen scales to setup my RC truck for a couple of years now, lol!
Cheers,
Gavin :)

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