millivolts to milliampere converter

Thread Starter

DRSP

Joined Nov 29, 2011
3
Hello I'm new at this forum.
In my project I use 2 different types of sensors.
Sensor one gives a signal between 0 and 60 mV
Sensor two gives a signal between 0 and 100 mV

I need to build a conveter to convert the 0-60 mV to a 4-20 mA signal
and a converter to convert 0-100 mV to a 4-20 mA signal.

Does anybody know the answer?
 

Adjuster

Joined Dec 26, 2010
2,147
What is your load device? What is its impedance, or alternatively, how much voltage will it require? What bandwidth is needed? Is it acceptable to have a monitoring resistance in the common return?

Answers to these questions, any other details you may be aware of, and perhaps a schematic of your expected arrangement will help people to comment on this.
 

Thread Starter

DRSP

Joined Nov 29, 2011
3
My device load is a PLC (25 ohms)
It will require 24V DC

it is acceptable to have a monitoring resistance in the common return!

The sensor is actually the same as a bridge of 4 resistors

Uploaded with ImageShack.us
 

ErnieM

Joined Apr 24, 2011
7,991
My device load is a PLC (25 ohms)
It will require 24V DC

it is acceptable to have a monitoring resistance in the common return!

The sensor is actually the same as a bridge of 4 resistors

Uploaded with ImageShack.us
In a 4-20 mA signaling system you are free to put a sense resistor anywhere you wish. The system assumes you have 3 elements: a signal source, a signal receiver, and a power supply. Note sometimes these may be combined.

One sticky point comes about if both of your sensors are electrically common. Then you probably want to isolate one so it can run in it's own current loop.
 

thatoneguy

Joined Feb 19, 2009
6,349
TI XTR101 Though not cheap.

Is this for an industrial application where accuracy is of utmost importance? If so, that is "The Standard" IC for the use you are looking at.
 

Thread Starter

DRSP

Joined Nov 29, 2011
3
TI XTR101 Though not cheap.

Is this for an industrial application where accuracy is of utmost importance? If so, that is "The Standard" IC for the use you are looking at.
This is for an industrial application where accuracy is of utmost importance!

Can I use the AD693 instead of the XTR101?
And do you have a compete schematic for this solution?

Thanks!
 
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