Where can i get a working ph meter circuit?
#The pH meter takes current input from a pH elctrode and displays the output in pH units. The pH electrode sources low current in Pieco amps at a very high impedance in 100s of meg. Hence to connect the electrode to the meter, we need a two pin connector that has very high impedance between the two contacts. As the elctrodes output current is low, we need an opamp with very high input impedance and low bias current. Ofcourse today we have pH meters in the market, which seem to use the ubiquitous 741 in the 1st stage. The choice of the 1st opamp is yours, mostly dictated by the price. I used 3140 IC which does an adequate work. Others used AD515 or TL084. Visit the following links: http://wind.prohosting.com/prakaash/ph/p… http://www.electronicsinfoline.com/Circu…
