Need to make 4 - 20mA loop isolators

[bowlingo]

Hi all,

I have a combined PH and CF transmitter of which can be found here

pH and Conductivity Transmitter

I need to make 2 x 4 - 20mA loop isolators that I can connect to each output. The unit runs on a 24V power supply

Someone has pointed me to some of the components

**broken link removed**

**broken link removed**

This will be the fist time I have made something like this and would like to do it on small prototype boards with chip housings etc.

Can anyone provide me with the correct parts from farnell or RS and possibly an easy to understand diagram?

I have used this device before but they are very expensive at £134.40 inc VAT

Buy Signal Conditioning Loop powered isol signalconverter,4-20mA RS MIN310 online from RS for next day delivery.

Thanks

 

[bowlingo]

Anyone any ideas on this please?

 

[FvM]

ISO124 is just an isolation amplifier, you need to supplement 4-20 mA receiver and transmitter circuits to form a full 4-20 mA isolator.

For industrial applications, it's reasonable to use ready-to-use units like the shown signal converter module.

 

[bowlingo]

ISO124 is just an isolation amplifier, you need to supplement 4-20 mA receiver and transmitter circuits to form a full 4-20 mA isolator.

For industrial applications, it's reasonable to use ready-to-use units like the shown signal converter module.

so they can not be easily made with a couple of components?

---------- Post added at 12:57 ---------- Previous post was at 12:52 ----------

I need to connect the PH/Cf transmitter to the AD inputs of one of these...

PICPLC16 v6 PLC System - PIC Microcontroller Board - mikroElektronika

Well someone else is coding it and providing me with diagrams etc on how to wire it but I am trying to avoid spending the cost of the board plus gsm module again on 2 x loop isolators

 

[FvM]

so they can not be easily made with a couple of components?

Depends on your understanding of easily. For minimum part count, you can use a simple shunt resistor on input and a 4-20 mA transmitter chip on output. TI/Burr Brown should have all required parts, their datasheets most likely have example circuits. All you need to do is to scale the signal levels correctly and provide the necessary power supply. All in all, it may be easier to use the ready made module. For the industrial application field, the price is quite reasonable, respective modules from major automation companies (e.g. E+H, pepperl-fuchs) are most likely more expensive.

 

[bowlingo]

so it isnt as easy as using something like this

**broken link removed**

with something to isolate each sides voltage supply? i.e something like this

**broken link removed**

use the same 24V supply from the PH/CF transmitter and solder the input and output signal wires on?

 

[bowlingo]

someone has pointed me in the direction of these


Sensors, Sensor Conditioning, 4-20mA Transmitter - 4-20mA Conditioning - RCV420 - TI.com


Any ideas on how what other components are needed?