HI
This is my first post and I hope somebody is able to help me.
I want to build a 4-20 ma analoge signal generator for test purposes, any DIY kit, website, schematics.
Thanks a lot

 

What controls this signal generator?

 

HI
This is not used to control but to test a simple ac motor drive or similiar applications. Thanks

 

Below is a relatively simple 2-20mA current source that will drive a grounded load. The transconductance is 1mA/0.1V (0.1mA output current increase for 0.1V input voltage increase). The op amp can be any standard rail-rail type op amp. The P-MOSFET can be virtually any device that has >=100mA and >=20V rating.

The circuit is relatively insensitive to small changes in supply voltage.

If you want to be able to adjust the output for exactly 2mA output with 0V input, you can replace R2 and R4 with a 20kΩ pot. That will also allow adjustment of the 2mA point for other supply voltages.

If you want to simulate the circuit with LTspice I can post the simulation file.

 

Thanks for the reply. I have seen some notes about IC XTR 110.

 

Thanks for the reply. I have seen some notes about IC XTR 110.

Looks like that may be a simple way to do what you want.

 

Thank you CRUTSCHOW for the reply. Any details on IC XTR110 except datasheet. Thank you

 

Thank you CRUTSCHOW for the reply. Any details on IC XTR110 except datasheet. Thank you

Look for Burr Brown's application notes. IIRC there are application notes for their 4-20mA loop related chips, yours included.

If have time I could look in my library.

/Edit

I had time and my library is just 2 m away from here...

There are two application bulletins in their Applications Handbook - 1994

AB-043
AB-165

Edit/