[GreenKeys] Motor start control

[John Nagle]

    It's an aftermarket product. It's covered by U.S. Patent
#4,030,010, "Time Delay Control Circuit", by Norman Schwartz
of Multiplex Communications, Inc., filed in 1975.

http://www.google.com/patents/US4030010

"A time delay control circuit comprising, a pair of input terminals, a 
capacitor, and a resistor arranged in series between the input 
terminals, a flip-flop, a first comparator connected across the resistor 
to set the flip-flop, a second comparator connected to one of the input 
terminals to reset the flip-flop, and resistance means connected across 
said input terminals and to each of said comparators to generate bias 
voltages for said comparators when voltage is applied across said input 
terminals, whereby the flip-flop is set in accordance with variations in 
the signal applied to the input terminals which are of a predetermined 
minimum duration established by the charging time of the capacitor.
2. The circuit of claim 1, further comprising a relay controlled by the 
output of the flip-flop, the relay being connected to the drive motor of 
a teleprinter."

    The circuit uses a 555 timer chip, which was apparently
considered a novel idea at the time.  I looked at the
schematic on the first page of the patent, and thought
"This guy re-invented the 555".  No, he just used one,
as it says in the patent text.

    The patent doesn't show a full wave bridge on the input,
so the polarity of the input signal matters.  Teletype
selectors don't care about polarity, but this box does.
According to the patent, lack of input (i.e. SPACE)
turns it on, and after 5 minutes with no input
(i.e. MARK holding) it turns off.

    Seems like a useful little device.  Apply a 9V
battery to the line terminals for 5 minutes and the
outlet should turn off. Any break should reset the timer.

			John Nagle

On 10/03/2014 12:37 PM, greenkeys-request at mailman.qth.net wrote:
> essage: 39
> Date: Fri, 3 Oct 2014 07:37:55 -0400
> From: "John P. Caldwell"<jcaldwell at rbcos.com>
> To:<greenkeys at mailman.qth.net>
> Subject: [GreenKeys] Motor Start Control ?
> Message-ID:<001001cfdefe$79aaf460$6d00dd20$@rbcos.com>
> Content-Type: text/plain; charset="us-ascii"
>
> I came across a couple of what appear to be motor start controls in a box of
> RTTY parts I picked up at a hamfest recently.  These are marked MULTIPLEX
> COMMUNICATIONS INC, Long Island, NY, Model MC110.  There's a barrier strip
> w/ contacts for Line +/- , Selector 1 & 2 and a switched 1/6A 120V outlet.
> The units are marked 5 Minute Delay, which I take to mean when the line
> contacts go hot, the timer starts.  My assumption is teleprinter in series
> with the box would then power up and remain so for the 5 minute duration,
> ready to receive a message?.  A google search yielded nothing
>
>
>
> Does anyone have any info on these units?
>
>
>
> Regards,
>
> John WD8INC