[GreenKeys] How hot is too hot? (Teletype 32)

Tue Sep 6 10:21:45 EDT 2022

Thanks guys for the helpful responses!  I am ashamed to admit that after an
excellent chat session yesterday (with the cover off - keep things cool) my
beloved 32 no longer properly wakes up when I receive a message or send a
test message from the i-Telex!  The motor runs, but no typing.  After about
7 seconds it shuts down. I wonder if I disturbed something removing the
cover, or maybe my resistor modifications finally broke something 😳😱...
iTelex seems fine as I can see messages coming in overnight by looking at
my TW39 serial port in tera term. cheers!  Andy

On Tue, Sep 6, 2022 at 6:56 AM Joe Duszyński <joeduszynski1 at gmail.com>
wrote:

> For the i-Telex,
> Better yet use a Diode and a momentary push button in parallel to
> short out the diode to dial out.
> You hold the button down while you dial the number and release the
> button when the current reversal happens,
> then the power consumption is Zero at idle. Fancy relays.... BAH!! LOL!
>
> 99% of the time the machine sits idle with i-Telex (unless you call out a
> lot).
> The diode will not affect the current reversal.
> If you have a machine that "only" sits on a subscription service and
> never dials out on I telex like I do,
> you don't even need the switch just the diode because all you are
> doing is waiting on a call (Current reversal).
>
>
> I made an "el cheapo" FSG for a machine without one, using a diode,
> momentary push button,
> a 100ohm resistor, optocoupler, a phone dial and a countdown timer
> relay set for 2 seconds.
> Even put it in a fancy 3d printed potted box with wiring terminals and
> everything! ;-)
>
> When the reversal happens the optocoupler trips and holds the timer
> relay, since the relay is set for 2 seconds the pulsing on and off of
> the message does not affect the relay and when the current reverses
> back to hang, up the relay shuts off in 2 seconds.
> When you hold the momentary push button down (only hooked across the
> diode not the optocoupler) you get full loop current to the dial and
> the motor stays off.
> If you want the schematic to make an FSG for a machine without one, I
> can send it.
> The one I built has been running 24/7 since April or May of this year.
>
>
> Some ITELEX FYI.....
> The i-Telex doesn't "look" for the really low idle current like a real
> telegraph exchange.
> In a real telegraph exchange there needs to be a really low idle
> current of around .004 ma.
> The i-Telex does provide this very low current but it does not look
> for it to exist. The i- Telex only cares that
> the current flow is lower than its threshold to register as an off
> condition. The i-Telex does not care if the current is present or if
> it exists at all.
>
> The i-Telex actually only looks for the circuit to go open or closed
> because the optocoupler can only sense "ON" and "OFF"
> The high impedance "low current" state of the FSG is the same to the
> i-Telex as an open circuit, it is sensed as an OFF state.
> The circuit is such that the really low draw won't activate the
> optocoupler.
>
> The i-Telex mimic's the operation of an exchange rather well but if
> you have a FSG that the high impedance relay draws slightly too much
> current
> the optocoupler then activates and the i-Telex will think the
> teleprinter has gone "off hook" and cause problems, in this case you
> have to add some resistance to
> the relay or if its circuit is adjustable "Adjust it" to negate the
> excess current draw and that can be a balancing act with an old
> finicky FSG.
>
> "The more you know"
>
> JD
>
>
>
>
>
>
>
>
>
>
> On Tue, Sep 6, 2022 at 4:25 AM Paul Heller <paul0926 at comcast.net> wrote:
> >
> > This is a good idea - stand the resistors off of the board as much as
> possible. Why not?
> >
> > Paul
> > W2TTY
> >
> > On Sep 6, 2022, at 10:14 AM, Henning Treumann via GreenKeys <
> greenkeys at mailman.qth.net> wrote:
> >
> > 
> > European (or better non Teletype) machines use a very sensitive
> polarized relay to detect
> > the current loop reversing of the TW39 system which switches the motor
> power relay after
> > an incoming call.
> > Hence stand-by power usage of an European Telex control unit is almost
> nothing.
> >
> > I would install the mentioned resistors on a small distance to the PCBs.
> >
> > And yes... it should be online 24/7 - that's the fun of i-Telex. :-)
> >
> > 73
> > Henning DF3OE
> > i-Telex 925302
> >
> > www.i-telex.net
> > www.telexforum.de
> >
> >
> >
> > Am Mo., 5. Sept. 2022 um 22:54 Uhr schrieb Paul Heller <
> paul0926 at comcast.net>:
> >>
> >> Nice machine!
> >>
> >> A fan is an interesting idea. A small one that runs off 120vac perhaps.
> >>
> >> I don’t have that insulator in mine and I think Wayne’s suggestion to
> remove it is a good one. I often leave the lid opened to let air circulate
> in there.
> >>
> >> It seems like a bad design. The European machines have a relay which is
> much better. I don’t know how they dissipate power from the small amount of
> loop current when not in a call, but I’ve not noticed heat build up in
> them. Yes it gets pretty warm and I often worry about that but so far all
> is doing ok on my machine. I do power it off when going away for any
> extended amount of time.
> >>
> >> Paul
> >> W2TTY
> >>
> >> > On Sep 5, 2022, at 4:37 PM, Andy KN4UCL <kn4ucl at gmail.com> wrote:
> >> >
> >> > 
> >> > Hey folks, I recently got my M32 up and running on i-Telex and all is
> good but things are getting a little toasty and I am not sure how much I
> need to worry.  Please see attachments - the circles I drew show where it's
> getting hot.  120-130F if my Harbor Freight thermometer is to be believed.
> >> >
> >> > As there is quite a bit of room in there, I was wondering if a small
> fan would be helpful.
> >> >
> >> > Any thoughts appreciated!
> >> >
> >> > thanks
> >> > Andy
> >> >
> >> >
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