[GreenKeys] Current Loop Converter

[wa2hwj at att.net]

The issue with most converters is that they are only good up to 30 vdc. That's fine for a 33 but not for a 28 or 15 hv loop. A 33 requires 20 ma at 24 vdc or thereabouts. If a 12 vdc reed relay is put in place of the 33 it can then key a hv loop. 
Jack K0TTY
 
Sent from my Verizon Wireless BlackBerry

-----Original Message-----
From: "Larry Tighe" <larryradio at worldnet.att.net>
Date: Fri, 11 Dec 2009 14:04:51 
To: <dhunter at islandregister.com>; Bill Horne<ehorne at speakeasy.net>
Cc: <greenkeys at mailman.qth.net>
Subject: Re: [GreenKeys] Current Loop Converter

Would the Black Box CL-051 do both currents?  I don't think it cares but for 
the max limit...well over 60 ma.and has the RS 232 input.

Too, couldn't the CL-050 simply key a low voltage reed relay to do the 
current keying???  They were going for a big $5 a piece at one time on ePay.

lar
K2JIA
----- Original Message ----- 
From: "Dave Hunter" <dhunter at islandregister.com>
To: "Bill Horne" <ehorne at speakeasy.net>
Cc: <greenkeys at mailman.qth.net>
Sent: Friday, December 11, 2009 1:16 PM
Subject: Re: [GreenKeys] Current Loop Converter


> 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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