Converter Current 4 to 20mA to 0 to 5V

Hi I need shield that convert Converter Current 4 to 20mA to 0 to 5V. Where do I buy?

Thanks

All you need is a 250 ohm resistor. Place the resistor across the current output of the Xducer. connect the junction of the + output and resistor to analog input. connect the negative Xducer output to Arduino GND.

Or, if you want some isolation, do what midi does and use an optoisolator.

An optoisolator for an analog signal?

groundfungus: An optoisolator for an analog signal?

There are.

High-Linearity Analog Optocouplers

Electronics is Art.

Linear optos work by feeding back to a circuit (usually an opamp) on the isolated side, it's not clear how they would be appropriate here.


Rob

I'll be darned. :) I had to check them out and I found a circuit in an app note for isolating 4-20mA. http://www.avagotech.com/docs/AV02-1847EN. learn something new every day, hopefully.

The circuit is pretty complex and probably not of use in this case but interesting to me.

groundfungus: I'll be darned. :) I had to check them out and I found a circuit in an app note for isolating 4-20mA. http://www.avagotech.com/docs/AV02-1847EN. learn something new every day, hopefully.

I voted your 250 ohm resistor solutions, the linear analog opto-coupler might be over kill here. However in dictionary of electronics no word "BEST" but "BETTER". We never know. treat it as art will make life easy.

I start this one before #7 but finished at #8, English Forum is not fair to Non-English speaking person. :*

Here are two other ways of doing an isolated 4-20mA converter:

  1. Use a digital isolator chip such as ADUM6401, with an SPI ADC on the isolated side measuring the voltage drop across a resistor.

  2. Put a 5.1V zener in the 4-20mA loop, and use that 5V power an ADC. Use it to measure the voltage drop across a resistor in the 4-20mA loop, and use 2 or 3 opto isolators to pass the signals between the ADC and the Arduino.

dc42: Here are two other ways of doing an isolated 4-20mA converter:

  1. Use a digital isolator chip such as ADUM6401, with an SPI ADC on the isolated side measuring the voltage drop across a resistor.

  2. Put a 5.1V zener in the 4-20mA loop, and use that 5V power an ADC. Use it to measure the voltage drop across a resistor in the 4-20mA loop, and use 2 or 3 opto isolators to pass the signals between the ADC and the Arduino.

I knew Dave will bring us better solution.

I add one more here;

  1. add 5V wireless power supply module to power ADC, Use it to measure the voltage drop across a resistor in the 4-20mA loop, and use 2 or 3 opto isolators to pass the signals between the ADC and the Arduino.