View Full Version : Converting 0-10v to 4-20ma

February 1st, 2003, 07:36 AM
Good Morning Everybody

I am wondering if there is a way to convert a 0-5v / 0-10v to a 4-20ma signal. This will help me make a decision on the type of input option I should use.

February 1st, 2003, 08:20 AM
in our place we have done it the other wat around that is gone from 4/20 mA to 0-10V in this manner.

with a ct that gives a 4/20 output and putting a 500ohm resistor across the 4/20 mA then taking the 0-10V signal off each leg of the resistor.

////// 500ohm
/ /-----------//---------
/ ct / //
/ / //
/ /-----------//---------
////// 4-20mA 0-10V
loop loop

I think thats right.


February 1st, 2003, 08:29 AM
sorry aboutthe diagram.
but basicaly up end up with two loops one being the 4/20mA the other loop being the 0-10v. And by putting the resistor accross the 4/20
this gives us the 0-10v loop on the otherside.

February 1st, 2003, 09:43 AM

February 2nd, 2003, 06:17 AM
I think the easiest and the most safe way is using an opto coupler (eg cny 17-3 )with a bjt (eg bc107) which can easily make the things happen accurately.

I have seen this kind of circuits very often used in voltage difference to current based communications if you want to have a predetermination you can see the circuit on http://www.runmode.com for s5 interface which is a rs232 com to s5 communication (which does have a voltage to current convertor) it needs a little change for the resistance to be comfortable for your use ....

Tom Jenkins
February 3rd, 2003, 07:53 AM
It looks to me as if you have the 0-10 VDC signal and are trying to get it to a 4-20 mA. The previous examples are for going the other way - if you had the 4-20 mA and needed voltage.

If you want to go from analog voltage signal to 4-20 mA the easiest soulution is to use a signal conditioner. These are from $150 to $300 depending on features, power, etc. They are widely available - APi, M-Systems, Action Instruments, Acromag, many others.