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[Trlog] Strange laptop LPT behavior

Subject: [Trlog] Strange laptop LPT behavior
From: k6ll at juno.com (Dave Hachadorian)
Date: Thu Mar 13 13:40:24 2003

On Thu, 13 Mar 2003 08:03:15 -0600 George Fremin III <geoiii@kkn.net>
writes:

>       Some computers do not have a pull-up resistor on the 
> parallel port
>       inputs. It might be necessary to provide pull-ups to +5 
> Volts on the
>       two inputs used by the paddle. This can be done by 
> connecting a 10K
>       resistor from each paddle input to pin 14 on the parallel 
> port
>       connector. Pin 14 is held at +5 volts and will pull the 
> inputs up to a
>       high logic level when the paddle input is open.

You can also supply the +5 volts from an external supply.
This frees up pin 14 to be used as a relay control port.

Dave Hachadorian, K6LL
Yuma, AZ

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