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[Solved] was: Need electrical circuit help (Rotating Monitor w. Parallel Port)
csa3d:
Hey folks!
So I've created this this parallel port circuit and have ran into troubles w/ windows booting causing pins 2 and three to swap from being low to being high. If this circuit sees 2 go high while 3 is low (or vice versa) then the motor turns. How can I prevent bootup from sending data changes to these pins?
Thanks.
-csa
DaOld Man:
see if another pin is also going high on boot up. If it is, place the highlighted part of your circuit back in, and tie the base resistor of Q3 to the that third output.
Thats one way.
richms:
You cant, the parallel port is used to output POST information on most machines for diagnosing motherboard issues, so thats why the lines will be toggling.
Even the serial port is not immune to this sort of thing with plug and play diddling with the handshake lines to get things to identify themselves.
You may be OK with an addin parallel port card, but my gut says the best way is to get an arduino or other simple microcontroller board that you can use instead, and put some code on it so you just send "vertical" or "horizontal" out the port, or look into an LED wiz or something and use pins of that instead.
DaOld Man:
The above circuit worked for me. (Used opto isolators instead of transistors, but same theory.)
On two different XP computers. But I had to use a different output on each, because a different output was left on.
On both however, all 8 outs are left on after windows boots.
Cametron:
How about running a delay circuit on the common ground? Set the delay long enough for the boot to complete.
Just my 2c.
Cheers
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