Printing input voltage of a potentiometer to an LCD screen

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Schematic v0.0 - Nano_LinPot_LCD
Schematic v0.0 - Nano_LinPot_LCD1268×686 86 KB

Hi forum people! I have a project on my hands and have very little idea where to start.

I really hope I don't irritate anyone by the nature of my post but here goes:

I am brand new to Arduino and brand new to coding but not at all an alien to computing.

My project is this:

  1. A device to scale the change in output voltage of a linear potentiometer.

  2. This scale is to approximate 'Kg' - as in mass.

  3. The mass will move a platform that pulls against springs.
    (i) The platform will be fixed to the slider of the linear potentiometer.
    (ii) My understanding is that the springs extend in a linear manner and likewise, the voltage change in a linear potentiometer is..linear.

  4. Therefore, I need a way to calibrate the range - which I am hoping can be done by using, say, a 1Kg weight. A multiplier value then needs to be calculated based on the (input?) reading for '1 Kg' and applied to all other (input?) readings.

  5. All scaled readings are then to be displayed (or 'printed'?!) to an LCD display behind the letters 'kg'

What advice can anyone give me? I have had a go at using an online schematic builder to assist communication.

Many thanks

Nick

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There is an example sketch in the IDE that reads an analog value and reports it via serial. That would be a good starting point...

I have had a go at using an online schematic builder to assist communication.

Don't bother. Just draw it with pen and paper and post an image of the page.

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Thank you, I've found it and yes, certainly looks like something I will try to explore :slight_smile:

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Springs are specified by how much they deflect per amount of force. So a 10 lbf/inch spring will deflect 3 inches with 30 lbf applied. Your slide pot will read from 0 to 1023 (10 bit ADC) when stroked over its length. If the pot has a 3 inch stroke it will read 341 counts per inch. Using the 10 lbf/inch spring you will get 341 counts per 10lbf or 0.0293 counts per lbf. So to scale the reading (0 -1023) to lbf (0-30) use force (in lbf) = analogRead(analog in) * 0.0293.

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Thanks for this too - I'm pretty sure I can use that and input my own spring data values - 0.33N/mm (or 33.65063493 g/mm).

1000 / 33.65 = 29.7

Therefore, 1Kg should deflect the spring 29.7mm

Therefore, 4Kg should deflect the spring 118.8mm - a travel length I want to try and stick to.

My max load will be no more than 4KG so...

I'm unsure what you mean by '10 bit ADC' - but - I have tried to look for a potentiometer with a track long enough for my anticipated <120mm extension --- Link to potentiometer product

...which I hope is suitable (electronically speaking in my limited knowledge)?! It was the only component I could find with a long enough travel.

The rest I can work out later.. but

  • if anyone is able to comment on whether my above linked component will be 'compatible' with my newly ordered Arduino uno, I'd really appreciate it!

Nick

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The A/D of an Uno can read/distinguish 1024 different levels, which is "two to the power of ten".

A 1 ohm 100watt (adjustable with a clamp) is totally unsuitable.
Look for a 10k linear slide-potentiometer with the required length.
Leo..

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