Hi
I have a EC meter (electrical conductivity) that uses an ICL7106 for display.
I figured that if I connect my DVM to the inputs INPUT HI and INPUT LOW
Or input hi and ground I can read the voltage which I can then connect to the
arduino. Then I should have access to the voltage in digital form.
Can anyone help on this?
Since I am only allowed one photo this is the product I got.
This is where I soldered the 2 pins to my DVM.
Wow, a blast from the past - I haven't used an ICL7106 in over 20 years. It is a dual slope integrating converter that came out in the mid 1980's.
It has a very high input impedance and typically has a 1meg ohm resistor in the IN-high path and a capacitor across the IN high and IN low. This may not be a problem if you are using a DVM on the input pins. It could be a problem if you are trying to use the A/D converter on the Arduino (it requires much more drive current than a typical DVM). You didn't explain how you were going to get from a DVM to the Arduino.
You also say you have an EC meter then show a picture of a pH meter - they are not the same.
The meter is DUAL MODE EC/PH .. So I figured all the circuits around there is basically furnishing the ICL7106 for displaying the final value... so can I intercept the value as it is going to the ICL7106?
I tried to measure the INLO and INHI with DVM but Got Zero volts... am I connecting something wrong? there are a few versions of the ICL7106 with the pin 1 marker at the center and this one is at the edge... so I guess I am correct.
Once I get the value to the DVM, I simply use a A/D converter board that outputs RS485 modbus to suck out the voltage destined to the LCD display.. thats my logic..
Can anyone help here? If not I just probably forget it and use an UNO with EC code
to get things going.
This is the ADC I intend to connect once I get a voltage reading..
Hi,
The Hi and Lo inputs the the 7106b are both above ground.
You need to measure Hi with respect to the PH meter gnd and Li with respect to the PH meter gnd.
Then subtract Li from Hi.
Resulting Volts = V(Hi) - V(Lo)
This you can do digitally after ADC of each Hi and Lo.
Tom.. 
PS. The reason your DMM could measure it is because your DMM is basically floating with respect to the PH meter circuitry.
Hi
My DVM READS ZERO VOlts... so Now to get a reading connect HI + and common and LI and common?
It could not measure it by connecting the DVM to HI and Low directly... so I will connect it to HI and GND/COMMON and see what happens..
Thanks for the help, will get back to see if there is any value.
Note that you will only be measuring mV, the 7106 is a 0 to 200mV ADC Display IC.
Thanks.. Tom..
Brought back memeoris for me 
39 years ago for me I designed everything elctrical/electronic for Protimeter back then (https://www.protimeter.com/)
Ok then thats it... Better to forget it and use exisint EC code than to try to suck this out..
not worth the effort and money.. Thanks
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