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### Topic: weight measuring arduino (Read 1 time)previous topic - next topic

#### epulse

##### Mar 18, 2011, 03:16 pm
Hy,

We neet te measure weight in arduino for a school project.
The idea is how more you weigh how brighther the licht becomes.

Does anyone have an idea how to do this?

#### WillR

#1
##### Mar 18, 2011, 03:34 pm
Yes -- lots of people know how to do this.

But... you need to explain the project much better. What weight, what are you measuring and so on.

Just another Hacker

#### epulse

#2
##### Mar 19, 2011, 12:50 pm
We want to weigh up to 3 people. So the measurment dusn't have to be real precisely.
We measure with steps of 60kg.

My native language is dutch, but reading englisch isn't hard for me.
Writing englisch is still a litle dificult for me. So this is a good exercise for me as well.

#### WillR

#3
##### Mar 19, 2011, 06:36 pm

We want to weigh up to 3 people. So the measurment dusn't have to be real precisely.
We measure with steps of 60kg.

My native language is dutch, but reading englisch isn't hard for me.
Writing englisch is still a litle dificult for me. So this is a good exercise for me as well.

Will they be standing on each others shoulders? Hanging from a rope? All sitting on the same chair? Standing on a platform you will build -- With force sensors (strain gauges) at the corners?

"doesn't have to be real precise"  Steps of 60Kg? Why bother? It seems useless. That is plus or minus the weight of a teenage student is it not?

Now do you mean the display is in steps of 60Kg -- or the sensors? I am not aware of how to build any weight measurement device with that level of inaccuracy. Maybe +- 6KG-10kg? Base on say three people of 60-80 kg each then... say 240KG +- 5% would be about right for a simple "dumbed down" project.

Always separate the "working part" from the display. Just like object oriented programming.

Why build something of say 30-50% accuracy. Use a weight guesser at a local carnival... it would be more fun and just as instructive.

Now if this is a project for kids under 13 OK -- but if this is a "High School" (Grade 10-12) project maybe you should define it a bit better.

Just another Hacker

#### raalst

#4
##### Mar 19, 2011, 07:31 pm
have a google for "DIY pressure sensor"

I believe I saw something with a wet sponge, and the arduino measured the resistance of the sponge.
that varied when the sponge was compressed.

or this
http://www.instructables.com/id/DIY-Force-Sensitive-Resistor-FSR/

or just put a wooden plate on something soft like rubber tiles or a few pillows
and measure the compression/movement of the wooden plate by means of a potentiometer

now where can I send the rest of your homework ;-)

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