Homebrew PCBs

----- Original Message ----- 
From: "Dave Mucha" <dave_mucha@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Saturday, May 22, 2004 7:39 PM
Subject: [Homebrew_PCBs] Re: New file uploaded to Homebrew_PCBs




>
> Good thing you fixed the crystal.  That was required to make it work
> and too simple of a mistake.
>
> A question is why the diode on MCLR ?

Possibly to discharge the capacitor that is often used on MCLR when power is
removed. However, there is no capacitor. 8-)

>
>
> Another question is why all the shift registers to only light a few
> LED's ?  And why the transistor on the LED's ?  The shift register
> can handle 20mA in a drain mode, and each LED can be run at 10mA so
> there are lots of unneeded parts.  OR... more likely many more parts
> that are not shown.

Perhaps the SRs are to minimise the number of outputs from the PIC, enabling
more LEDs to be added without taking up more pins.


>
> It seems the PIC could easily handle the 6 LED's shown, more easily
> than the way shown.  Really makes me think things are not shown.

>
> I would think the LED's are 'typical' for stings of 8 or so, like bar
> graphs.

Leon
--
Leon Heller, G1HSM
http://www.geocities.com/leon_heller