[GreenKeys] Fw: Loop supplies

[hwhall at compuserve.com]

A loop supply is so simple to make, I can't see why anyone would want to spend "several" times $10 each to make an HV supply out of several LV supplies.

>if fed by almost perfect waves from the converter it may stand a chance of working

What "waves" (from a DC supply)? 
No matter how perfectly one turns on/off the DC supplied to the magnet coil, the coil current is still going to have a limited rise time. Unless I'm mistaken, the "dv/dt" calcs already assumed a perfectly square on/off applied voltage

 

 Wayne
WB4OGM

 

-----Original Message-----
From: JC White <jcw1231 at pacbell.net>
To: greenkeys <greenkeys at mailman.qth.net>
Sent: Tue, May 17, 2016 9:30 pm
Subject: [GreenKeys] Fw:  Loop supplies



run several of the modules in series??



  
 
 
  
----- Forwarded Message -----
 From: Ralph Mowery <rmowery28146 at earthlink.net>
 To: epvgk at limpoc.com 
Cc: greenkeys at mailman.qth.net
 Sent: Tuesday, May 17, 2016 8:27 PM
 Subject: Re: [GreenKeys] Loop supplies
  
 

I did just order a couple of the boards from China so should know something
in a few weeks.  The boards are suppose to have an adjustment for the
current along with the voltage so an external resistor will not be needed as
if it was just a voltage board.  It may not even work at all, but thought it
may be worth a try for about $ 10.  

It was also mentioned in another post about using such a low voltage supply.
I know about the dv/dt (rise time) of the current, but if fed by almost
perfect waves from the converter it may stand a chance of working
,especially if the teletype uses the lower inductance of the holding coils.
I would like to have close to 100 volts or more, but did not see any modules
that would put out that kind of voltage and regulate the current for a few
dollars.  I will have to look around and see if there are any.

De Ralph ku4pt



-----Original Message-----
From: epvgk at limpoc.com [mailto:epvgk at limpoc.com] 
Sent: Tuesday, May 17, 2016 7:49 PM
To: Ralph Mowery
Cc: greenkeys at mailman.qth.net
Subject: Re: [GreenKeys] Loop supplies

On Tue, May 17, 2016 at 07:18:01PM -0400, Ralph Mowery wrote:
> While I have not tried them, ebay has some modules from China that 
> might just work for a local loop.  Buy one of the modules which is 
> just a circuit board and look around for a 24 volt wall wart DC 
> supply.  The modules are only about $ 2 to $ 6.  Some of them can be 
> adjusted for a constant current and should be able to put out about 20
volts for the 60 ma loop.
> 
>  

You should be able to use one of those with my CL adapter board, but you'll
need a small current limiting resistor as the board already puts 187 ohms
total in series with the loop. (plus the dc resistance of the selector
magnet coils, etc)

eric

> 

______________________________________________________________
GreenKeys mailing list
Home: http://mailman.qth.net/mailman/listinfo/greenkeys
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:GreenKeys at mailman.qth.net

2002-to-present greenkeys archive: http://mailman.qth.net/pipermail/greenkeys/
1998-to-2001 greenkeys archive: http://mailman.qth.net/archive/greenkeys/greenkeys.html
Randy Guttery's 2001-to-2009 GreenKeys Search Tool: http://comcents.com/tty/greenkeyssearch.html

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to jcw1231 at pacbell.net




 
 
  

______________________________________________________________
GreenKeys mailing list
Home: http://mailman.qth.net/mailman/listinfo/greenkeys
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:GreenKeys at mailman.qth.net

2002-to-present greenkeys archive: http://mailman.qth.net/pipermail/greenkeys/
1998-to-2001 greenkeys archive: http://mailman.qth.net/archive/greenkeys/greenkeys.html
Randy Guttery's 2001-to-2009 GreenKeys Search Tool: http://comcents.com/tty/greenkeyssearch.html

This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html
Message delivered to hwhall at compuserve.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/greenkeys/attachments/20160518/c5549d75/attachment.html>