[GreenKeys] Current Loop Converter

[Dave Hunter]

Hi Bill:

ASR33's have a 20 ma loop. 15's, 28's standard loop is 60 
ma. (the 28, I believe can be set up with a 30 ma. loop but 
it isn't standard). Mine is 60 ma.

That is why I am looking for a unit capable of switching 
either, as I am looking for a 33 for the museum, and want 
to be able to use the same device for either machine...

I wil check out the links you found. I did a search for 
them this morning, and found only the more expensive of the 
two. What I am looking for, though is a design which people 
have actually used, and now works well.

Thanks,

Dave

Dave

On 11 Dec 2009 at 11:22, Bill Horne wrote:

> Dave Hunter wrote:
> > Hi All:
> >
> > Does anyone have for sale a current loop to RS232
> > converter which is selectable between 20 or 60 ma loops?
> >
> > Alternatively, can anyone recommend a commercial product
> > which they use to drive an ASR-28 from a computer, also,
> > to drive an ASR33 from the computer (future project)...
> >
> > I realize these can be built, but as a diabetic with
> > eyesight which is now beginning to give me problems, it
> > will be simpler to purchase a suitable pre-wired device...
> >
> > Dave, VY2AC
> >   
> *Dave,
> 
> I seached for "(rs232,rs-232,rs232c,rs-232c,rs-232-c)
> current loop" on e-pay, and came up with several offers,
> which average about $50.
> 
> Here are the first two:
> 
> http://tinyurl.com/ya2dtnk
> **http://tinyurl.com/yezs64r
> 
> HTH.
> 
> By the way, I've just realized that I don't know what the
> "standard" current loop value was: I'm used to 60ma from
> Model 15 machines, but I don't remember what the Model 33
> used, and I never worked on the Model 28. I know the 33's
> had a built-in driver assembly that used transistors to
> deliver ~500ma to the magnets, but I don't recall the
> default input current value during "marking" conditions.
> 
> Was the current value a strapable option in the
> 15/28/whatever, or did the 20ma machines have to have the
> special selector magnet assemblies that reset the armature
> mechanically before each pulse?
> 
> Bill, W1AC
> *
> 
> -- 
> E. William Horne
> William Warren Consulting
> Computer & Network Installations, Security, and Service
> http://william-warren.com 781-784-7287
> 
> 
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