[GreenKeys] Re: Constant Current Loop

[Tim McNerney]

Sure.  Send along your schematic drawings, and I'll post them on my web 
site, http://www.4004.com

--Tim


On Jan 23, 2007, at 4:01 AM, greenkeys-request at mailman.qth.net wrote:

> From: "WB6BLV" <wb6blv at inreach.com>
> Date: January 22, 2007 9:28:38 PM EST
> To: <GreenKeys at mailman.qth.net>
> Cc: Subject: [GreenKeys] Constant Current Loop
>
>
> For a long time I have experimented once in a while with constant 
> current
> loops for my TTY equipment.  Long ago Irv Hoff gave a presentation at 
> WA6YKY
> (Northrop Institute of Technology, Inglewood, Ca) that included 
> information
> of holding the current constant in a loop as various combinations of
> machines were patched in and out.  Back then we used a 6V6 with a 1K
> wirewound in the cathode as a means of making the current pretty much
> independent of the number of selector magnets in the loop.  I have been
> using a solid state desing on and off for several decades.  If you 
> have any
> interest in a copy of the schematic, including nominal component 
> values for
> 20 and 60 mil loops (GIF or JPG format), please contact me off-list.
>
> 73
>
> John
> WB6BLV at inreach.com
>
>
>
>
>
>
> From: Sheldon Daitch <sdaitch at mor.ibb.gov>
> Date: January 23, 2007 3:01:05 AM EST
> To: WB6BLV <wb6blv at inreach.com>
> Cc: GreenKeys at mailman.qth.net
> Subject: Re: [GreenKeys] Constant Current Loop
>
>
> John,
>
> Northern Radio made a loop current regulator module, solid state,
> way back in the 1960s.  I first ran across them in the Army, in
> TTY loops in comm sites and later found 'em in our VOA TTY setup
> in Greenville.
> IIRC, it has one or two low level transistors, a current regulator
> pass transistor, and a handful of resistors and maybe even a
> zener.
> Very simple to reconstruct, if I can find a copy of the schematic.
>
> 73
> Sheldon
> WA4MZZ
>
> WB6BLV wrote:
>
>> For a long time I have experimented once in a while with constant 
>> current
>> loops for my TTY equipment.  Long ago Irv Hoff gave a presentation at 
>> WA6YKY
>> (Northrop Institute of Technology, Inglewood, Ca) that included 
>> information
>> of holding the current constant in a loop as various combinations of
>> machines were patched in and out.  Back then we used a 6V6 with a 1K
>> wirewound in the cathode as a means of making the current pretty much
>> independent of the number of selector magnets in the loop.  I have 
>> been
>> using a solid state desing on and off for several decades.  If you 
>> have any
>> interest in a copy of the schematic, including nominal component 
>> values for
>> 20 and 60 mil loops (GIF or JPG format), please contact me off-list.
>>
>> 73
>>
>> John
>> WB6BLV at inreach.com
>>
>>
>> _______________________________________________
>> GreenKeys mailing list
>> GreenKeys at mailman.qth.net
>> http://mailman.qth.net/mailman/listinfo/greenkeys
>>
>
>
>
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