Talk:PPM Meter Alt

PPM Meter Discussion

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Temperature Compensation

Has anyone added a temperature compensation function yet??

Shure, why not...

Use the circuit below. No hard to find pieces , cheap and small sensor too

For the diode probe use a piece of shrink wrap tubing for waterproofing

The results for my probe are plotted on the next graph

The precision is pretty good if you make a 2 or 3 point calibration like the one on the above graph

" Sorry for the mess maybe someone will arrange it a little ;0) "

thank you very much, this looks very easy to make! Wikisysop

Interesting reader comments on probe design

Got this in an email, seems useful so posting here:

"I want to measure conductivity in limewater (for a marine fish tank), so I want an electrode for highly conductive solutions (around 10mS/cm).

After a bit of thought, I used two propelling pencil leads (0.7mm diameter) - I needed only a few mm exposed spaced by say 5mm. Readings after a few months are stable, so graphite leads seem ok for this application. (And to calibrate, just draw a line to make the electrode shorter!)

Clearly they're not suitable for everything, but they are readily available."