Help with Salinity and ORP circuits

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Jorge Ramalho
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Joined: Sun May 25, 2014 5:09 pm
Location: Rio de Janeiro, Brasil
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Help with Salinity and ORP circuits

Post by Jorge Ramalho »

Hi!

I'm building a controller based on a Arduino Mega 2560 and some stackable shields made by myself. The idea is to build the controller slowly, learning with it. I must say ReefAngel has helped me a lot with it's solutions for some circuits and software, as well.

I managed to build some shields and now it has RTC, EEPROM, Temperature, dosing pumps and the power unit (relay) command. I'm building now the probes shield which will have pH, ORP and Salinity. I see your pH is driven at 5V, same as Arduino, so it's ok. ORP and Salinity are driven at 9V. I don't want to use a lot of wires and cables to connect all modules, so I'm building stackable shields. Might the Salinity and ORP circuits be driven in a derived subnet of 9V since I'm driving arduino at 12V. I wonder if I use a voltage 9V regulator (7809) I would be able to use RA ORP and SAL circuits with no modifications.

In another thread someone has written the circuits need to be galvanic isolated, is it true? Can't I just connect the output of the gain OPAMP to an analog in pin of arduino ?

By the way, I'm not an engineer or electronics specialist, I'm building this controller to learn electronics.
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