Interference problem between LED dimming and pH sensor

Other Hardware LEDs and Multiplexing
1

I am making a circuit which converts PWM to 0-10V connected to Meanwell ELN-60-48D for dimming and an Atlas Sci pH stamp to TX1/RX1 for pH Reading. Both things work without problem if individually connected but pH reading is interfered if connected at same time. I checked the dimming terminals of ELN-60-48D as some AC current, I think this is the reason why pH reading is interfered. Any method can fixed this problem?

I follow this circuit to make the PWM to 0-10V conversion

Thanks!

2

Is this the PH Stamp, https://www.sparkfun.com/products/10972
This is a regulator for leds, Meanwell ELN-60-48 - PSU IP64 48V 1.3A - MeanWell.nl Power Supply webshop

I don't understand how you use them.
If you use them both for your aquarium the Ph readings are not stable. Is that the problem ?

A led regulator is the noisiest thing around, and the PH stamp is very sensitive. Those two don't combine very well. Shielding and grounding and galvanic coupling is not easy. But if you search the forum for "ph aquarium" you should find some threads with equal problems.

3

The ELN-60-48D is use for aquarium LED lighting, arduino output PWM signal to controls dimming.

4

That is even worse. The very sensitive PH sensor is connected via the Arduino with a PWM for the Led regulator.
Perhaps you can isolate the PH sensor from the Arduino. It was on this forum, you have to search for it.

5

Thanks for advise :slight_smile:

6

You need something like in this thread, http://arduino.cc/forum/index.php/topic,136059.0.html