Making a pH sensor

Yeah, I've looked at this myself, there is loads of stuff on t'web ... just google ph sensor circuit or similar. There are some simple single op-amp circuits I think.
Del

brei... kirimin dong ke saya, klo ada gbr rangkaian sensor ph... trims... :) dwijayateguh@yahoo.com

Yeah i couldnt find any without the pH sensor that give me a reading accurate to 1 degree error

I have googled and tried all the home stuff including buying anthrocyanins and making a chart... apparently it is not as good as they say it is.

Oh ... and I wanted to MAKE or MIMIC the electrode. Not use the standard electrode... to get the desired result.

Couldnt find much myself

Oh, sorry you want to actually make the sensor itself...
I think you are fighting a losing battle there...dunno how they are made...I just assumed it's v specialised/difficult/impractical.
If there was a simple way we'd all be doing it.
I want a simple Cu 2+ sensor...but no one knows how to do that either....

Unfortunately not everything has a simple solution....thta's why my hobby is making nice simple things... (bows)
Del

THANKS !

I am going ahead with it though! Currently i am trying to make my solution behave in a way that can help me do it.

Will compare fluid behaviour at some key points where i put in the probes...

Let me work on it and maybe i cud write bac with some way we all can!!!

Another way is to have some indicator that is 'adsorbed' on to a surface which will react to the material and later is to be washed. This thing has already worked so thats well. But the accuracy is questionable unless i use a colorimeter or a spectrometer to measure it... which is too much work for a cheapskate like me. Hehe...

Open to more suggessions tho.

Ok! so here is where i got to ...

There are beads of zeolite that are used to soften hard water. The principle of working is having embedded ions on it's surface that react to the ions in the water and saturate themselves. They have to be regenerated for repeated use. This kind of a thing may work for your Cu2+ issue Del ... provided you embed it with the right ions ofcourse.

Meanwhile... my pH sensor too had a similar principle. There is an immobalized indicator in the form of beads.

Immobalization is a common biochemical enzyme assay technique used wherein an enzyme is trapped within a protein such that it participates in a reaction without really spoiling itself or mixing with the substrate. You can remove and reuse the beads on washing.

I used egg white to form the beads... and immobalized the indicator. Ofcourse, the color chart is a bit altered. Am still playing with the chemicals to get the best mix to give me dark colors. So far I got result upto an error of 2.

Have not been able to reuse or 'clean' the beads well yet so... ahem... have to work on that too, else it isnt a sensor right? Also, more complicated and heavy the indicator is, the better the results so that too is some place for improvement.

If anybody knows any large bulky organic indicators of pH, lemme know...

until then... please pray that i do not blow up my kitchen.