[GreenKeys] Tape Reader Power Resistor

[Joe Duszyński]

This one is Marsland not Ohmite (like Pepsi and Coke)  ;-)  I would have
said RC but I don't ever remember seeing RC Cola in the UK.

https://www.ebay.com/itm/144438952816?hash=item21a13b8370:g:nZkAAOSwj8diHhcw

On Thu, Jun 9, 2022 at 8:24 AM Ethan Blanton via GreenKeys <
greenkeys at mailman.qth.net> wrote:

> Troy Peterson via GreenKeys wrote:
> > Does anyone know where I can find a replacement? I did a
> > cursory search of my usual (UK) component suppliers and 850 ohm
> > doesn't even seem to be a common value, let alone available in high
> > power. I'm not sure what the power rating of this resistor is, or
> > really even what kind of resistor it is...
>
> According to the wiring diagram, that 183081 printed on it is the
> Teletype part number.  I would ask Paul at RTTY Electronics
> (mr_rtty at pacbell.net, he's on this list) if he has that part number,
> since you say you'd like things to remain original.
>
> Keep in mind tha thet wires don't have to carry a large current if
> they are carrying a large voltage!  Many current loop devices in
> Teletype circuits may drop a small number of mA over a large voltage,
> which is a significant amount of power.  I don't actually know what
> the valid range of voltages for a 20 mA current loop is (I'd be
> interested to know, in fact), but for a 60 mA current loop it's quite
> likely to drop 60 mA at 120 V or more, which is over 7 watts -- but
> can be easily carried on 30 gauge wire (or even smaller!).
>
> I doubt the precise resistance is critical here, although a different
> resistance may entail (for example) adjustments to the current source.
> It looks like you need to chase down the schematic for the board
> that's on (the wiring diagram I checked just shows the resistor wired
> to "Board Assembly Reader Power Pack", part 183087) and see what it's
> doing.  Wire wound resistors are often relatively precise, so I could
> be wrong.
>
> Ethan
> ______________________________________________________________
> 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 joeduszynski1 at gmail.com
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/greenkeys/attachments/20220609/22e7ff83/attachment.html>