hi guys:
I am trying to use four DZ261 photo coupler, I am not sure the voltage will change when the sensor's output voltage go through the photo coupler. The reason I come up with this question is because the diagram of photo coupler is like a transistor with led as trigger. I am not sure if this thing can cause and gain or lose to the sensor's signal. Does anyone have the answer?
If you want to use an opto coupler to transfer and analogue voltage you gave to compensate for the non linear responce of it. This normally involves a coupler with two photo transistors and an op amp doing the linearisation.
I am using multiple thermocouple with DZ261. and then connect to one MAX31855. The channel selection I choose demultiplexer. I wonder if the thermocouple single can be transfer to MAX31855 through photo coupler without losing to much single accuracy?
I wonder if the thermocouple single can be transfer to MAX31855 through photo coupler without losing to much single accuracy?
I would not have thought so. You need enough voltage to turn on the LED in the opto coupler and you won't get that from a thermocouple.
Sorry I should make the point clear. I use demultiplexer to switch between each different photo coupler, but I wonder if the thermocouple's output after photo coupler will still be the same or almost the same as it's output without photo coupler.
but I wonder if the thermocouple's output after photo coupler will still be the same or almost the same as it's output without photo coupler
No.
As I said you need a linerising circuit something like this:-
