On Thu, 8 Aug 2019 16:09:23 +0100, Martin Brown
wrote:
snip
However, I understand the Arduino's only have a 10(12 with a tweak)
bit ADC and so with 10 bits I'm only going to get 1024 output values?
eg, If that was a 1kg 'scale' then I could read around 1g increments
but if it was a 5kg scale then ~5g would be the smallest increment
(that may be fine but I am just testing my understanding here).
Yes. You should be able to get 12bit or 16bit ADCs relatively cheaply
provided that you don't want fast ones and can live with a bit of
non-linearity.
I don't need fast but not sure about linearity (how much to expect).
I you want strict linear then you will have to calibrate
it against a reliable voltage reference source.
Understood.
Or is the output of the little eBay strain gauge amps already serial
so if it was a 24 bit device (16777216) it would be resolving down to
~1/3000 of a g (mathematically at least) and so would just use the
Arduino to turn it into ASCII over a USB interface (no ADC needed)?
I'd expect a simple strain gauge to output either a resistance value,
That seems to be the way most I look at are.
voltage or current depending on its internal design.
Ok.
Yo will have to
think about shielding from air currents and all sorts of mechanical
details if you want to go more precise than 10mg.
1g will be more than enough. ;-)
I know you can buy commercial strain gauge to ASCII over USB devices
but they aren't exactly cheap (~£250+).
Decide what resolution and accuracy you need first and work from there.
Well, the thing is (for this experiment), as long as I know I can get
(commercially) the right stuff, then that's covered. For my
experiments I was interested to see how close to that I could using
d-i-y level money / kit.
The 'Arduino level' strain gauge amps I've seen on eBay are supposed
to be 24bit and if true and assuming I can make use of that level via
something that would easily turn that into a stream of ASCII data on a
PC USB port ... then I'll probably be happy. ;-)
https://learn.sparkfun.com/tutorials...n-gauge-basics
https://learn.sparkfun.com/tutorials...ith-load-cells
https://www.sparkfun.com/products/13879#
It looks like that one uses the I2C interface so if it's really 24bit
internally then I should still get that resolution though the Arduino
(as it's not using it's 10bit ADC's)?
Cheers, T i m