1
\$\begingroup\$

I want to implementate this device, mentioned in the title.

The problem is how to correctly build the " read out device" that is clearly a wheatsone bridge?

But in AC, the problem is the signal conditioning for a frecuency between 1-20khz probably I suppose that I need to use an OP AMP stage and an AC to DC meter after it.

Nevertheless the whole thing needs to be very acurrate. Any advices? enter image description here

The final goal is to interface with arduino.

Thanks!

\$\endgroup\$
3
  • \$\begingroup\$ Define very accurate. I made a little circuit for measuring water conductivity a few months ago. AC drive voltage, SS probes in water, TIA opamp circuit to measure the current. Done. (Well the hard part is the calibration.. I didn't do that.. but easy to see changes when a pinch of salt was added to the water.) \$\endgroup\$
    – George Herold
    Commented Mar 23, 2015 at 13:22
  • \$\begingroup\$ very accurate is that the device no need to be so acurate like the comercial devices that cost arround 200$ but enough for monitoring the conductivity . I can not give you more dates I still dont have the aknowledge of the magnitudes. \$\endgroup\$
    – manualm
    Commented Mar 23, 2015 at 17:38
  • \$\begingroup\$ can you share your circuit? please? \$\endgroup\$
    – manualm
    Commented Mar 23, 2015 at 17:38

1 Answer 1

Reset to default
1
\$\begingroup\$

Sure the TIA (trans-impedance amp) converts a current to a voltage.

schematic

simulate this circuit – Schematic created using CircuitLab

V-water is not a battery, it's the electro-chemical response of the water/electrode. I'm not sure exactly what it is... you'll have to play around with the frequency.

\$\endgroup\$
1
  • \$\begingroup\$ thats true, water is not a battery deppending on frecuency it´s more capacitive or lees, but in this frecuency only have a resistive behaviour \$\endgroup\$
    – manualm
    Commented Mar 25, 2015 at 12:52

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.