I'm looking for a spring balance that can be set to light up in different colours according to pre-set and adjustable parameters.

So for example if force/weight is under 1lb, light is blue, 1-2 lb orange, 2-5 lbs red etc. or you could set it so that if force is under 2 lb = blue, 2-7 orange, 7-10 red.

I need to be able to set 5 weight/force ranges.

I was always crap at physics - Any ideas?

Eventually you are going to have to run any response through a chip to turn a variable resistance into an output ... if you dont get along with physics then you are going to have a problem as the simplist way I can see is to have a changing resistance and then calibrate that.

I think I will try a mechanical solution. Cheers.

I think Hir is right.. you're going to need some form of chip for a process, albeit a fairly simple one.. probably a decent comparator circuit with the right addons could do it..

Logic chips are going to be absolutely the easiest way to do this, but i have in my head now a picture of a standard scale.. You know the ones with the hook on a spring, and a sliding indicator bar on a scale like they used to use for fishing scales? the ones you can hang a bag on..

You'd have to build in some kind of addon that could be clipped to multiple scales, and would use the indicator bar on said scales to make an electrical contact with different points on the addon to mechanically switch the light on.

0lb |orange

1lb |red

2lb |green

3lb-|blue <light on

where the - is the indicator bar on the scales.

To change the scale from 0-3 lbs, to say 1 to 7 lbs, you would have merely to use an identical scale with the relevant spring. But the logic gate is liable to be easier to operate, and you can actually buy scientific scales that already do this - indicate the weight on a set of LEDs as well as a LCD display.

hope this helps...

chips with everything these days,whats wrong with making the mechanical pointer magnetic and a line of reed switches going from the lowest to highest readings you need,each reed switch turns on an led of the appropriate colour

That right there, mad hippy, is a more reliable, better version of what I said.. i never considered reed switches.. :duh: @ me

Those would work too for the adjustable scale, if you set it up like a binary counter.. There would be more than one row of LEDs, each row signifying one scale.. that could be worked.. I need an 8th to work this out, at this time of night

what do you mean by a spring balance? but yeah, first thing i thought of was microswitches, no need for electronics.

I didn't really explain it very well. I was thinking of a fishing type balance with a piece of string attached to it, to practise pulling steadily at different forces. looking at a coloured light would be easier than squinting at the pointer. My brother pointed out that a balance could be hooked up to a tube with different colours on it running down the centre of a larger tube with a slot cut out, so one colour could be seen at a time. You would adjust the lengths of the coloured pieces.

to practise pulling steadily at different forces

Take a look at the 'power meter' on a Bullworker.

Simplest solution I can think of now is just paint cake segments of a clock display in diffrent colours. Simply look to see if the indicator is in desired colour. Should you wish to redefine these permeters one just paints the face again.

to practise pulling steadily at different forces.
surely excessively technical- i call it wanking

I find that it pays to have some form of detection apparatus with wanking to avoide friction burns and lacerations...

You could try Quantum tunneling cable , its a cable that changes resistance acording to the pressure applied to it .(if i remember correctly )
place a ring under your pots , as they grow and get heavier they would change resistance allowing for possible variable voltage LED 's which change colour with different voltages . eg 5 v might show blue , 9 v orange etc .

One thing tho , it would be hard to calibrate any system like this because everytime you water ,your lights would change colour because of the weight of the water then slowly change back as your plant takes up the water and becomes lighter again

cool idea but not sure how practical it is ,

good luck mate

stickyrussian

What is the application for your device?