4 to 20 mA generator help

[Snap]

Thanks, but I don't need all the bells and whistles and would like to build it myself (to learn). There has to be an easy way to do this I am just missing something. I just need a start. I see the problem might be where to put the extra amps when I throttle them down from 20 to 4. It I pulsed the pic like controlling a dc motor speed it might work but what does that do to the amps? I think there is a IC that might work has anyone done this before?

[mackrackit]

I think there is a IC that might work has anyone done this before?

Did you read the thread from the first post?
This was in there
http://www.maxim-ic.com/appnotes.cfm...te_number/722/
has a list of chips.

[Snap]

Duh, I cant believe I missed that. I must have been too caught up in your picture.
I will order one and see if I can modify it. I will post results thanks.

[aratti]

Try this simple circuit using a LM350 and 120 ohms pot, it should resolve your need.

See the attached diagram.

Al.