Subject: Re: More newbie questions about the PC164
To: Dave Huang , Ty Sarna <>
From: Dave McGuire <>
List: port-alpha
Date: 04/16/1999 17:57:43
On Fri, 16 Apr 1999, Dave Huang wrote:
>This would be really neat though :) Drawing from my almost nonexistant
>electronics knowledge, I think something like a 74LS74 flipflop would
>work, with Q' tied to D and the PWR_ON# line, CP with a pulldown
>resistor to ground and a connection to +5VSB through the momentary power
>button. Would some debouncing on the switch be needed? I dunno how to do
>that :) And I also don't know how to make sure the flipflop powers up in
>the "off" state. It's got a reset pin, but I don't know how to pulse it
>when the power first comes on...

  Debounce the switch with a 74LS123 one-shot multivibrator or a 555 timer
based circuit...can probably get away with three or four components that
way...the 'LS123 is a dual one-shot; maybe you can use the other half to reset
the 'LS74 upon powerup.

       -Dave McGuire