[GreenKeys] How hot is too hot? (Teletype 32)
Paul Heller
paul0926 at comcast.net
Wed Sep 7 01:06:10 EDT 2022
Andy, I’m confused. Mine works differently.
Mode 1: local mode
- Teletype in ready to receive mode: all lamps out, motor off, a few ma of current
- press local button. Teletype comes on in local mode. Can type. Not sure current draw. - Stays on until I press stop button
Mode 2: Telex Mode
- Teletype in ready to receive mode: all lamps out, motor off, a few ma of current
- Press and hold the start button for one second. Dial Lamp comes on, motor still off
- Dial a number
- when finished dialing, I-telex turns the motor on, current goes up to 40ma and a call is made
Does local mode work for you?
You can see mine operating here:
https://www.youtube.com/watch?v=v4risjgiX1E
Hope it helps
Paul
W2TTY
> On Sep 7, 2022, at 1:36 AM, Andy KN4UCL <kn4ucl at gmail.com> wrote:
>
>
> Good evening/morning folks! After wasting a good amount of time on a blown fuse in my low-grade multimeter, I finally managed to measure the current between the Teletype and the i-Telex. Below are my findings
>
> Teletype + i-Telex powered on: 4 mA (Dial lamp illuminated - motor starts to run but does NOT run "open")
>
> If I press STOP button on Teletype: 58mA (Dial lamp extinguished)
>
> Similarly, if the Dial Lamp is illuminated, and if I try and dial a number - the motor switches off very quickly.
>
> And finally - if I press the Test button on my i-Ttelex, the motor spins up and shuts down after about 7 seconds (no printing.)
>
> Thank you for your guidance!
> Andy
>
>
>
>> On Tue, Sep 6, 2022 at 11:03 AM Andy KN4UCL <kn4ucl at gmail.com> wrote:
>> Hey Paul I have the single TW39 card... ummm let me see if I can use my multimeter to measure the current 😱😊
>>
>>> On Tue, Sep 6, 2022 at 10:34 AM Paul Heller <paul0926 at comcast.net> wrote:
>>> In my case the resistor mods were not enough. I never understood why, nor did Russ. It still drew way too much current and I blew up the TW39 port. Do you have a dual TW39 card? Maybe try the other port?
>>>
>>> I had to add additional resistance in the loop to get the current down to 40ma.
>>>
>>> Be sure to measure your loop current and keep it around 40ma.
>>>
>>> Paul
>>> W2TTY
>>>>> On Sep 6, 2022, at 4:22 PM, Andy KN4UCL <kn4ucl at gmail.com> wrote:
>>>>>
>>>>
>>>> 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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>>>>> >> >
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>>>>> >>
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>>>>> >>
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>>>>> >
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>>>>> >
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>>>>>
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>>>>>
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>>>>>>> 1998-to-2001 greenkeys archive: http://mailman.qth.net/archive/greenkeys/greenkeys.html
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>>>>
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