Generating Power from 4-20 mA Signal

[hemavm9081]

Hello,

Just wondering whether is it really feasible to generate required power say some 3.3V and 24V for operating ICS with a max load current of 1A each from standard 4-20mA current loop signal

 

[IanP]

Continous power of 1A from 4-20mA has to be treated as a joke, but stealing “limited” power from current loop is quite a common practice ..
If, however, you temporary need "some" power here is how it can be done:
Power Supply From 4-20mA Transmission Line
**broken link removed**

Rgds,
IanP

 

[hemavm9081]

thanks Ian,

I need total of 3mA consumption from 4-20 mA signal for my PCB.
But, my PCB needs +/- 24V and 3.3V .

all my components work with power requirement in range of uA.

So, here my concern is how can i get a stable input voltage for my respective regulators to generate the required voltages as my current loop signal woul;d be varying continously.

//Hema

 

[IanP]

Have a look at the attached picture ..
It shows the concept of draining <4mA from 4-20mA current loop ..

The 1N5311 is a 3.6mA current limiting diode, if you don’t have it you can replace it with J-FET ..
Connecting the gate and source of JFET (eg. 2N5457) together creates a current limiting diode ..

All what is lost is ≈5V, but who cares, you still have around 19V for the rest of the loop ..

Rgds,
IanP
:|