[GreenKeys] Leaving ASR-33 powered on...?

Mon Nov 26 13:59:24 EST 2018

Some form of 'Autostart' might be better.  The device on eBay shuts off all power to whatever is plugged
into it.  It would create fewer 'garbage characters' on startup if loop current was there at all times.
If the voltage and dropping resistor are carefully chosen, there would not be excessive power wasted or
heat.

Most, if not all TUs who were 'published' after 1965 or so, had an Autostart circuit that controlled a
relay which controlled the motor (only) of the Teletype.  Loop current remained.

There were some schemes that shut off loop current some time later for power saving.  This might create
just a few 'garbage characters' at start up.  Probably less than the entire machine whirring into action,
and applying voltage to the loop circuit.

The timed drop out of the loop supply would also have some 'garbage characters' at start up but probably 
fewer of them, since the machine 'went to sleep' with loop energized, then the loop was de-energized.

Just a thought.

Ralph - W8ROI

-   -   -   -   -   -   -   -

On Nov 26, 2018, at 1:49 PM, W9DDD wrote:

> That would work great, except it depends on how you are feeding the 33 a signal.  According to the description his box expects a serial loop at 60ma (or perhaps also 20ma).
> 
> John, W9DDD
> 
> On 11/26/2018 12:39 PM, Jordan Spencer Cunningham wrote:
>> It just so happens that an idle line timer dropped on eBay over the weekend along with a handful of 28s and other equipment (someone must be clearing out their stash as it's all from the same seller and for reasonable prices considering there are people on eBay trying to sell 15s in pretty bad shape for thousands of dollars!):
>> https://www.ebay.com/itm/Teletype-Idle-Line-Motor-Control/132849886265
>> No relation to seller and other such standard disclaimers.
>> You could probably build one of these yourself, though I don't know exactly what the guts would be. I'm controlling my 15 and 19 through a Raspberry Pi, and I have the Raspberry Pi set up to control some relays for the motors /and /current loops. Since I know via software when the loops are going to turn on and messages come through, I didn't have to build anything special like this to sense when the loop is idle or not-- the Pi just switches on the loop, the motor, and then sends messages through the loop. Pretty neat contraption, though-- I'd never heard of them before I saw this one show up on eBay.
>> --Jordan
>> On Mon, Nov 26, 2018 at 11:25 AM tony.podrasky <tony.podrasky at gmail.com <mailto:tony.podrasky at gmail.com>> wrote:
>>    There was a thing called an "idle line timer".
>>    You'd connect it into the loop, and plug the teletype
>>    into its outlet. When the loop keyed, it closed a relay
>>    and the machine would come to life. You could adjust the
>>    timing of how long it would keep the relay closed.
>>    It might be "me" - but I wouldn't leave the 33-ASR running
>>    if it's not being used - it's almost entirely hardware and
>>    there is only so much life in the machine.
>>    UE,
>>    K2EAA - TONY
>>    NNNN
>>    ZCZC
>>    On 11/26/2018 10:05 AM, Barnett, Andy wrote:
>>     > Hi folks, I know the ASR-33 is a light duty machine and apologies if
>>     > this has been covered before, but I would appreciate your thoughts –
>>     >
>>     > 1.            OK to leave my ASR-33 powered up and running? (but not
>>     > printing much, mostly waiting)
>>     >
>>     > 2.            Has anyone ever built a gizmo that powers on the
>>    Teletype
>>     > from cold when there’s some activity on the serial line… and perhaps
>>     > powers off after no activity after a while?
>>     >
>>     > Thanks!
>>     >
>>     > Andy
>>     >
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