4 digit auto-ranging frequency-meter.
Dave VanHorn email (remove spam text)
>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.
Are you SURE they will turn off? Look at the pin specs for minimum
high output voltage, and leakage current. I've got my doubts about the
current design, but IIRC, they can drive closer to ground than to VCC.
See also: www.piclist.com/techref/index.htm?key=digit+auto+ranging
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