EC meter

waits ... staggering and underwhelming response to the question ... waits ... hmmmm.... think I'll take up sewing......

I was hanging about waiting for an answer, as I'm also vaguely interested - I actually had one of them sticks with the LEDs and had wondered whether I could have rolled my own.

I've posted this circuit (at the bottom of the page) before:

it could do the job?

Since you've shown interest, if you give me a contact I'll pass on what I get. Thanks.

Well, I was waiting to see what responses you got first because I don't have a circuit either. What I can tell you is I reverse engineered a digital one with a LCD display once and traced out the circuit (which I no longer have). However I can tell you that there were two probes about 1cm apart. One probe had a AC signal of around 1V, 100hz cap coupled to it. The other probe was connected to a precision diode op-amp amplifier circuit which rectified the signal and the DC output of this circuit was fed into the micro. The dc level would increase with increased conductance between the probes. It was fairly simple really. I suppose you could always get one of those cheap "truncheon" EC meters with the LED's, open it up and trace out the circuit.

Regards, Dean.