4 to 20 mA generator help

[Snap]

Sorry I ment to say A 250 ohm resistor should convert 0 to 5 volts to 4 to 20 mA.

[mackrackit]

Sorry I ment to say A 250 ohm resistor should convert 0 to 5 volts to 4 to 20 mA.

Thought so, just checking

[Snap]

Cool Halloween picture.

[mackrackit]

Cool Halloween picture.

Thanks!
What I look like now and what I will someday look like

[ronjodu]

In my old days as a service tech I used this.

http://www.kele.com/olcat/TE7/CLC-100.PDF

Unfortunately I don't have a schematic for it. I think it sells for around $600 without the PWM option. There's got to be a cheaper way to roll your own.

[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.