how to connect multiple inputs like 150 sensor volatges to arduino mega
Welcome to the forum
More details of the sensors please
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Hi, @pyal_p
Welcome to the forum.
Can you please tell us the application of your project?
Thanks.. Tom... 
How fast do you want to retrieve these many values?
I suspect an X/Y problem. Please tell us more about your project.
Are they digital signals, or actually analog voltages? What's the signal range? Information please.
Hello everyone,
Thank you for the response and guide lines.
i am into automation. have used arduino in many different projects
let me explain the project that I spoke about. I will be recieving 4-20 mah from different RTDs (temperature sensors). I am using 4-20 mah to 5 volt convertor module and sendingthe voltage to analog pins. Now if I use different pins then I will need many arduino mega boards. Can i use multiple input signals . If yes , Can anyone help me in telling me how this can be done. By qualfication I am into IT but arduinos for many projects. Thankl youin advance
Analog multiplexers like the 4067 come to mind. 16 inputs to one output.
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As @sterretje mentioned, there's the 4067. Sparkfun have a board ready to go for 6 USD:
The also sell this beast that handles 48 analogue inputs:
But I don't know if it's stackable or not.
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Close together or widely separated?
Here is a thread that may help you: 150- inputs on mega / uno
4-20 inputs can be done with a sensing resistor, typically 250 ohms if feeding a 5V input adc. For your number of signals, I'd put a 4067 input mux(post #11) on each ADC input of your Mega until you get to your required number of signals. Then, in software, simply scan the N inputs, change the address of all 4067 simultaneously, and scan again. You may wish to do a bit of n-bit averaging to reduce input noise, but that's easily done. Ask if you want more details.
Please provide a link to the specs for that sensor module.
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I assume that you me mean mA (milliamps) rather than mAh (milliamp hours) which is a different thing altogether
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Yes you are right, my typo error, 4-20 mA
Connecting is easy, making them work is another matter. Sorry I cannot help with either as I do not know what we are talking about nor do I have any technical details on the sensors. You are also missing a performance specification and a lot more. Good luck!
Hi, @pyal_p
What is the overall project that needs 150 temperature sensors?
How often do you need to read them?
Thanks.. Tom..
Hi Tom,
its for temperature and totaliser sensors with 4-20 mA output,
Why does your project need to read 150 sensors ?
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Part of the production process
Production of what ?
Are you aiming to read all 150 sensors in real time ?