Current Loop to RS232 Converter

[Shaun22]

Hi,

I would like to build a current loop to RS232 converter but have been batteling to find a circuit. I am looking for anything from 25mA to 40mA as I would like to finish a project I am working on. Does anyone know where I can find a circuit and parts list for such a device or does anyone have one? Any assistance will be greatly appriciated

Thanks in advance

 

[Nigel Goodwin]

Hi,

I would like to build a current loop to RS232 converter but have been batteling to find a circuit. I am looking for anything from 25mA to 40mA as I would like to finish a project I am working on. Does anyone know where I can find a circuit and parts list for such a device or does anyone have one? Any assistance will be greatly appriciated

Thanks in advance

It used to be quite common, but I haven't seem a circuit for many, many years - I can't even remember now what the current used actually was (although 20mA sounds vaguely familiar!).

I did have a nice simple circuit at home somewhere, I'll see if I can find it, but I'm fairly doubtful that I can now.

From what I can remember, it's quite easy to do - I'm sure someone else will have more recent info.

 

[Shaun22]

Hi Nigel,

Thanks for the response, yes a 20mA circuit is an industry standard although I require a higher current rating, I dont think it will be too difficult to modify the circuit to suit the current. Thanks anyway.

 

[Dialtone]

You were not specific as to what type of current loop converter you needed, but here is one for TTY-RS232 current loop.
http://www.e-insite.net/ednmag/archives/1998/080398/16di.htm#circuit

There are a few others listed on this site depending on application.
http://www.discovercircuits.com

Dialtone