[GreenKeys] AutoStart

[John, W9DDD]

Right, somewhere in the garage is a panel with a motorized 5 minute 
timer from the surplus market.  I can't recall the details, but a space 
transition on the loop would hit the reset coil on the timer which 
started the motor.  Five minutes of continuous mark in the loop let the 
timer run out and turn the motor off.  This was used on VHF with the 
squelch muting the RX output to the TU.  The TU was adjusted for a 
slight bias towards mark.

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The above comments or recommendations are SWAG. Use at your own risk.
John, W9DDD

On 8/31/2021 4:06 PM, Steve Garrison wrote:
> But it doesn't have to be associated with a TU at all!
> 
> A long time member of this group designed and built a motor control board based on a 555 timer controlled through an opto-isolator that used the loop current to 'measure' the length of the marking current after characters stopped coming in.  After an adjustable length of time with no start bit, the circuit would "time out" and open the contacts on a relay, that controlled the AC to the motor.  Then when the first start bit was received the circuit was reset and the relay closed thus turning on the motor.   I have recreated a new version of Jack Hart's, K2TTY, board and if I ever get around to assembling the ones I promised to other's of our group, I'll probably make another run of boards.
> 
> Steve G./N4TTY
> 
> -----Original Message-----
> From: greenkeys-bounces at mailman.qth.net <greenkeys-bounces at mailman.qth.net> On Behalf Of jim at k6ccc.org
> Sent: Tuesday, August 31, 2021 4:47 PM
> To: Greenkeys <greenkeys at mailman.qth.net>
> Subject: Re: [GreenKeys] AutoStart
> 
> From: "steve bennett via GreenKeys"
>> How does autostart work?Is that functionality built into the teletype
>> machine or is it done  in a TU or somewhere else?
> 
> In it's simplest form, it's a function of the TU.  The TU decodes Mark tone, or Space tone, or both to determine that there is a valid signal and then turns on AC power to the TTY.
> 
> When valid signal goes away, the AC power is killed to the TTY.
> 
> 73
> -----
> Jim Walls - K6CCC
> jim at k6ccc.org
> 
> 
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