PLUS . . . if you tie the collectors of the transistors to the UNREGULATED
supply, the 5V regulator is nice and small and cheap.

>Dave VanHorn wrote:
>> The displays are seven segment common cathode, it looks like a 4 digit
>> multiplexed array, but four singles in paralell would work as well.

>
>You can still minimize the parts by having the 7segment common anode,
>make all the colllectors of the NPN transistors tie to the +5V supply
>and reverse/invert drive to the LED (to the negative side).  This way
>the base resistors is not needed anymore.
>
>Reggie

dwayne


Dwayne Reid   <dwayner@planet.eon.net>
Trinity Electronics Systems Ltd    Edmonton, AB, CANADA
(403) 489-3199 voice     (403) 487-6397 fax