Hi, I am quite a newbie at electronics and specifically the Netduino. I would like some help on setting up the relevant circuit to allow me to do the following:
I have a sensor that communicates on a range of 4mA to 20mA based on what it senses. I would like to monitor this reading with the Netduino. The sensor has two outputs used to connect an external monitor (Netduino) to it. A postive and negative analog connection.
Could anybody help me with what I need in the circuit to connect this sensor to the Netduino? I would really appreciate some help
Analog Read
Started by DracoRSA, Jan 27 2011 02:09 AM
4 replies to this topic
#1
Posted 27 January 2011 - 02:09 AM
#2
Posted 27 January 2011 - 03:19 AM
Could you post a link to the specific sensor?
#3
Posted 27 January 2011 - 07:15 AM
Could you post a link to the specific sensor?
The product information can be found at Hanna Instruments
http://www.hannainst...8931A&id=017006
#4
Posted 27 January 2011 - 01:39 PM
Well I'm stumped. I don't think the netduino can measure current directly. You might need something like this that outputs varying voltage:
http://www.sparkfun.com/products/8883
http://www.sparkfun.com/products/8883
#5
Posted 27 January 2011 - 02:50 PM
Well I'm stumped. I don't think the netduino can measure current directly. You might need something like this that outputs varying voltage:
http://www.sparkfun.com/products/8883
Thats overkill!
You only need a resistor. Calculated by Ohms law.
You need a voltage drop of 3.3 V at 20 mA, and then you just measure the volage over the resistor with the analog input of the Netduino.
165 Ohm at 20 mA gives a drop of 3,3V (max for the Neduino analog input) (U=R*I)
I would select the one closest below 165 Ohm I can find, with 1% accuracy I would take 162 Ohm.
/Jan Olof
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