Not as stable as when I have it away from the aquarium, but stable enough: On top of the aquarium it goes from 7.6 to 7.9 and away from the aquarium it stays between 7.7 an 7.8 If you set the cup of water on top of the aquarium is it still stable. Ok thanks, I will have to get a 1uF capacitor once I have one I will try this setup and then I'll be back with the results.Īnother Question. Sorry I should have known ASCII diagrams are not useful. Just to make sure I understand correctly: Assuming the PH sensor does not generate a fast output signal I would add: Turning off all my other electrical devices doesn't seem to solve it.ģ) The arduino analog inputs require at a minimum and RC filter at the board. When I measure the same water in a cup, I'm getting a steady reading. The issue is that when i have my probe in the aquarium, the pH reading goes all over the place - from pH 4 up to 11. Hope that'll make some things more clear. I've attached some photo's of my test setup. The 5k can go higher but Atmel suggests this resistor not exceed 10k. The 5K limits the noise current to the 1µf to aid it in shunting the noise to ground. The 1µ (must be ceramic or film type) is to shunt the noise to ground and not allowing it to reach the 100 ohms. (limits current from the 1µ to the processor) The 100 ohms is to protect the arduino input from the voltage at the 1µ if the arduino is suddenly grounded at its power input. The specific values are not very important. Assuming the PH sensor does not generate a fast output signal I would add:Īrduino A0 - 100 ohms -|-5k ohms-twisted wires to your ph sensorĪll three components should be located right at the arduino board. The arduino analog inputs require at a minimum and RC filter at the board. where the board gets power, how long the wires are. If you posted more information about the physical layout of the "system". And even if you used the isolated Analog - Analog as MarkT mentioned the DC-DC could still cause issues by injecting noise at the sensor. My first thought is the DC-DC converter could introduce another source of noise into the system. I agree with that is is best to resolve the problem with more basic methods if possible.
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