Talk:PPM Meter Alt

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Thanks
  
* hmmz, it should zero... If its otherwise reading okai u may try increasing value of r15 to 100K or a little more. Lemme know if this helps. @_@ [[User:Wikisysop|Wikisysop]]
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* hmmz, it should zero... If its otherwise reading okai u may try increasing value of r15 to 100K or a little more. Also check the power supply voltages are symmetrical (should be +/- same voltage) Lemme know if this helps. @_@ [[User:Wikisysop|Wikisysop]]

Revision as of 16:48, 1 June 2009

Contents

PPM Meter Discussion

This page is for:

  • questions
  • comments
  • etc...

Temperature Compensation

Has anyone added a temperature compensation function yet??

Shure, why not...

Moved this to its own page Temperature_probe May 31 2009 >:D 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."

thanks...

seems you're good not only in electronic stuff but also in water analysis...  :)

Thanks for such informative and helpful project.

any update on those meters?

like to see your project.......possible?

how's your old meter?

tc.

  • thanks for the encouragement. ^_^ I was considering the other night posting the complete source code for the meter. As far as updates, since the meter is working for the moment I've been using it without much changes. Would really like to add in the temperature compensation circuit provided by ElAMPO, for temperature compensation on the pH/PPM readings. :D Hmmz, lastly been using the meter pictured on the page since 2006. Thx again, ~ eris - 2009/03/13

Is There a Trick to Zeroing

Hi,

I'm trying to build the conductivity meter but am having trouble getting it to zero. I adjust v2 to midrange (using a meter) and then try to adjust v3 to get pin 14 to read 0 volts. I can't get any closer than -1.87.

V3 is about a 20 turn resister and V2 is probable about 10 so I should have good resolution.

Is there a trick to zeroing it (the first time)

Thanks

  • hmmz, it should zero... If its otherwise reading okai u may try increasing value of r15 to 100K or a little more. Also check the power supply voltages are symmetrical (should be +/- same voltage) Lemme know if this helps. @_@ Wikisysop
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