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Converting bathroom scales to corner scales
v8kid - 2/1/08 at 11:16 AM

I've made up some natty levers to double the capacity of conventional bathroom scales and can now measure and adjust my corner weights nicely.

The trouble started when I thought it was time to go digital and ( after buying 4 sets of scales!) discovered that the blessed things will only stay on for a short time and then reset. Not long enough as it happens to nip round the car to note the readings.

Anyone out there know how to bypass the battery saving circuitry?

nick205 - 2/1/08 at 11:18 AM

Can't help, but have you got any pics or a description of how you are using the scales/lever set-up. I'd like to have a go at this.

v8kid - 2/1/08 at 11:21 AM

Will put pics on the suspension forum next week - garage is a bit of a mess just now as I'm converting the trailer to a box van.

Dangle_kt - 2/1/08 at 11:21 AM

Ditto! I bought 4 old skool scales from tesco for a couple of quid each and they will happily weigh my part built car, but I would prefer an option for when its fully built (with an engine!)

The guy who built th vfr powered locost , it's yellow in his sig and from malta (I think) is VERY good at electronics so u2u him.

I'll try to find his name.......

speedyxjs - 2/1/08 at 11:21 AM

quote:
Originally posted by nick205
Can't help, but have you got any pics or a description of how you are using the scales/lever set-up. I'd like to have a go at this.


Yeah me too. I was as it happens looking a scales this morning and wondering how much it was going to cost me

[Edited on 2-1-08 by speedyxjs]

Dangle_kt - 2/1/08 at 11:24 AM

TKS is his name. Bet he can help. He is a bright chap when it comes to electro-wizardry. He frequents the Electrics section, so you can U2U him from there, or just type his name into the message.

matt_claydon - 2/1/08 at 11:26 AM

I very much doubt you'd be able to do anything to the electronics unless you're into reprogramming a microprocessor but you could try bouncing/rocking the car a little every few seconds. The scales probably turn off a certain time after the reading last changed.


[Edited on 2/1/08 by matt_claydon]

v8kid - 2/1/08 at 11:33 AM

Thanks chaps emailed TKS.

Bouncing the car starts the zeroing process on the scales and they read....zero!!

Rats

matt_claydon - 2/1/08 at 11:53 AM

quote:
Originally posted by v8kid
Thanks chaps emailed TKS.

Bouncing the car starts the zeroing process on the scales and they read....zero!!

Rats


When they're already on and reading a weight? Surely that would mean when you were standing on them they would zero just by you moving a bit?

Dangle_kt - 2/1/08 at 12:13 PM

the ones in our bathroom zero if you tap the middle wit your foot. Maybe it is misunderstanding the bounce of the car.

Couldn't you just lean on the car on the way round to the other scale, it would set it off recalculating and buy you enough time to get there?

v8kid - 2/1/08 at 01:56 PM

Must be different functionalities of scales about. I just tried it with her indoors scales and they lock the reading. Bouncing makes no difference

The ones I bought from aldi give a moving readout for a few seconds and then freeze. bouncing causes them to restart at zero.

tks - 2/1/08 at 03:02 PM

quote:
Originally posted by v8kid
Must be different functionalities of scales about. I just tried it with her indoors scales and they lock the reading. Bouncing makes no difference

The ones I bought from aldi give a moving readout for a few seconds and then freeze. bouncing causes them to restart at zero.


the problem is that the bouncing means the thing thinks you get of it.

sow when you put it on (many times on the front) then you see 0.0kg then you stay on it until it gets a stable reading.

once it gets his stable reading it assumes you have seen it, if you then move it things you have left the scale.

the only thing i can think of is to just look at how it measures....

i'm pretty sure that it just gives a voltage.
sow its dead easy to do an convert to some way.

the most easy thing would be to see the scales as sensor and just hook them up together to a board (wich has 4 adc) the board can send the answer to a display or an computer dead easyly. I daily build board wich can comunicate with a computer.

only bad thing is that you need a computer standing by.

a display would then be a better option.
(but more work/money)

Tks

ruudbeckers - 2/1/08 at 03:08 PM

Can't you remove the displays from the scales and make a cable between the scales and the displays. Then mount all four displays next to each other in a nice housing. Then when you drive on to the scales, you can read all four of them at ones.

[Edited on 2/1/08 by ruudbeckers]

tks - 2/1/08 at 04:26 PM

quote:
Originally posted by ruudbeckers
Can't you remove the displays from the scales and make a cable between the scales and the displays. Then mount all four displays next to each other in a nice housing. Then when you drive on to the scales, you can read all four of them at ones.

[Edited on 2/1/08 by ruudbeckers]


this is an idea BUT:
- those signals are weak signals, sow the wire lenght is against this.
- it could be easyly being allot of wires going to the display, depending on the type of it it could be easy 12 wires each.

I would scrafice one, open it up.
look at the sensor. Hook it up to an puter.
use a 2nd scale to calibrate the new one.

then transfer all of them. job done.

Tks

ruudbeckers - 2/1/08 at 04:54 PM

But you can also take out all of the electronics except the pressuresensor itself, which has probably 2 wires. However, I don't know if the scale will still work with a long wire and if the long wire will have any influence on the measurement, but this can easily be tested. I think this is easier than designing a circuit board with 4 ADC's.

indykid - 2/1/08 at 04:54 PM

i'd package them back up as best i could, return them and say you got them as christmas presents for family but swmbo got something else and go get some analogue ones.

i can't see any way you're going to be able to work quick enough to do everything if they're anything like the digital scales we have.

tom

Hellfire - 2/1/08 at 05:07 PM

I'd second what Tom says. Just return them to the shop and swap for something more suitable.

Phil

v8kid - 2/1/08 at 05:27 PM

Whats an ADC and are they difficult to use?

indykid - 3/1/08 at 06:39 AM

i'm guessing an analogue-digital converter.................but all that electronics talk went straight over my head, despite doing a term of lectures at uni around this sort of stuff.

confused? that's why you want analogue scales with dials

tom

v8kid - 5/1/08 at 11:16 AM

Yea think you are right I'll stick to the analogue scales.

Anyone want some digital scales hardly used?

jacko - 5/1/08 at 01:19 PM

Get 3 mates to help you then go for a beer