Possible to use 7447 to drive common-cathode 7 segment display?
Yes, it's possible. One method would be to use two extra resistors (plus the usual per-segment resistor) and one PNP transistor per output. 







simulate this circuit &ndash; Schematic created using CircuitLab

You can buy these three parts integrated into so-called "digital transistors" so it would take only 7 additional parts. 

Edit: Re comments by sherrellbc, here is a version for a high-voltage LED digit (something like a 3" digit with multiple LED die per segment) that operates the transistor in the linear region. It provides a constant current of about 15mA for any LED voltage from 0 to more than 10V (it will get warm at 0V). 

When it is 'on', the base is at 12V - 2.2V, so the emitter is at about 1.5V below +12 and therefore the collector current will be close to 15mA (since emitter current ~= collector current). 







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