On Sunday 14 March 2004 00:31, Dwayne Reid wrote:
> At 05:18 PM 3/13/2004, Matt Marsh wrote:
> >Actually, I was just wondering, could I just use another
> > tranistor when selecting the porta pin so that power would then
> > be taken from the main positive power rail? (I might be way off
> > here...)
>
> Yep - use an NPN transistor such as the 2n4401.  Pinout is: leads
> down, flat towards you (so you can read the number) - left to
> right is EBC.  Connect C to + supply, connect B to PIC pin,
> connect E to display.  The neat thing about this is that you can
> connect C to the un-regulated supply if you wish - that way, the
> display current does not come from the +5V rail.  In effect, you
> move the heat dissipation from the 5V regulator to the driver
> transistors.

Very interesting point! I shall bear it in mind, thanks!

Matt

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Matt N. Marsh
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