Silly question - what are you using to draw your schematics?
Rob.
Totally OT
Mate is it Matho or Metho cos that's a Methanol in your avatar
Bad Alcohol
MHB
i was wondering when someone would notice, just a joke on the chat that chappo continues with, i had 'meth' up as my avatar for a while but thought metho better.
cheer's
steve
thanks for reading and i hope this has inspired a few to do similar projects
and I thought it was your pom pom dog...
QldKev
Thanks for sharing :icon_cheers:
Rob.
Great work Steve,
I will have to come down and see it in action soon.
regards
Graeme
ok here are some schematics
View attachment 38811
R1 adjusts the gain of the amp and R2 adjusts the supply voltage. R2 is needed because the amp can only supply an output voltage that is about 1.5v below the supply voltage so when i went to calibrate it, i first set the gain to full on the amp then adjusted the supply voltage to give an output voltage of 5v that would be full scale of the analog to digital converter. Then i adjusted the gain of the amp to give me a voltage rise of about 48.8 mV per litre of water.
R3,4,5,6 are there to represent the load cell, the 4 load cells are arranged into a wheatstone bridge so that two opposing sides go up with load and the other 2 opposing sides go down.
Only just catching up on this thread after matho posted in the arduino thread.
Very neat solution.
Just wanted to point out that you can get pretty cheap instrumentation amplifiers on ebay these days, like the AD620 or INA129 that simplify the circuitry. They can swing pretty close to the supply rails and can achieve gains of 1000 needed for load cells like this very easily. Just one external resistor needed to select the gain.
Stolen from this article:
http://www.ehow.com/how_5980113_make-load-...se-arduino.html
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