Re: 0 - 10 VDC to 4 - 20 mA conversion

Alan,

I drew up a quick circuit that should work. I'm on vacation so I'll
have to post it to the files section this evening as a jpeg called 4-
20mA.

Mariss

--- In CAD_CAM_EDM_DRO@y..., flyspeck1@a... wrote:
>
>
> OK, this one should be pretty simple. Does anyone have
> a quick and dirty circuit that will convert a 0 to 10
> VDC output on my DAC to the required 4 to 20 mA input
> signal (input impedence of 250 ohms) on my VFD? And no,
> I do not have control of the DAC!
>
> V = IR
> 1 volt = (0.004 Amps)(250 ohms)
> 5 volt = (0.020 Amps)(250 ohms)
>
> Believe it or not, this is the first time I've actually
> run into a situation like this. I've done a fair amount
> of digital design, but when integrating with the outside
> world in was always with control over a DAC (etc) and
> have been going into 2K plus impedence. This project is
> retrofitting a new VFD to an existing CNC control. As
> such, I don't have any ability to control the DAC.
>
> Thanks,
> Alan