Clarification and help with Transistors in LED Matrix

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i'm not familiar functions of electronic parts know transistor can amplify current. first off, know use, pnp or npn. planning shift registers send signal transistors amplify current each led needs 20 ma function. have 1 shift register turning on anodes while other turning on cathodes. have right idea? no heavy terminology please , if have heavy terminology please clarify means.

pnp anodes. npn cathodes.

but leds don't need 20ma run. that's max can take. bright @ 10ma, , still ok @ 5ma, if modern high brightness type clear lenses.


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