[GreenKeys] New To Group

[Mike Douglas]

Hi Dennis,

I'm presently finishing up a low power, regenerative loop driver that provides a 60ma interface to a Model 15 with both RS-232 and ITTY audio input connections. The RS-232 port provides bi-directional ASCII/Baudot conversion as well as baud rate conversion so the computer can use a common baud rate like 9600. The audio input demodulates clean FSK as provided by ITTY and sends it out the loop.

The loop driver is unique in that it does not require a high voltage supply, nor does the board include a switching supply to generate a high voltage. Instead, a regenerative approach is used in which the snubber circuit for the selector magnet coil captures the energy from the mark to space transition onto a high-voltage capacitor, and then dumps that energy back into the selector magnet during a space to mark transition. The dump from the high voltage built up across the snubber capacitor rapidly builds the inductor current which is then topped off and held by the low voltage supply.

I currently have the first version of the PCB in my hands and hope to find time very soon to stuff the board and begin testing. If this sounds like something that might be useful to you, stay in touch with me by email.

Mike

> On Jan 24, 2021, at 3:47 PM, Dennis Hanley <dennis.hanley at gmail.com> wrote:
> 
> 
> Thank you all to everyone for welcoming me, and for the pointers!
> 
> I've been reading the messages, and will try to keep the silly questions to a minimum :-)
> 
> Dennis
> 
> 
> 
>> On Sat, Jan 23, 2021 at 1:38 PM Dennis Hanley <dennis.hanley at gmail.com> wrote:
>> Good day everyone,
>> 
>> I have recently discovered this forum, and have finally got up the nerve to post something.
>> 
>> My name is Dennis, KB6C.  I discovered ITTY a while back, and was wanting to get my old Model 15, that's been in storage for over 40 years, up and running on that service.  (I also have a 28ASR that's still in storage).  I am looking forward to re-living the sounds and smells of these old beasts!
>> 
>> In the process of poking around on line, I stumbled across a simple demodulator that was apparently made by Eric Volpe about 2010.  Can anyone tell me if that device might still be available?  Or maybe a similar device with similar capabilities?
>> 
>> Thank you in advance for any advice you may have.
>> 
>> 73,
>> 
>> Dennis
>> 
>> 
>> 
> ______________________________________________________________
> 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
> 
>>>> Jordan Spencer Cunningham's GreenKeys Search Tool: https://teletype.net/gksearch
>>>> 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 deramp5113 at yahoo.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/greenkeys/attachments/20210124/86d65c16/attachment.html>