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Transistors

Former Member
Is a

BC549 TO-92 NPN general purpose transistor any good for the below schematic?

 

Sorry the schematic is 2 images but I couldn't fit it all on one screen.

 

Cheers,

Chris
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Led Cube Schematic.rtf
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  • 0 in reply to Former Member

    It looks very much like you will be multiplexing the outputs and will only be switching on any pair of transistors for a brief period. As long as you do not exceed the current limitations of the BC547 100mA or 200mA pulsed you should be ok.

    I would seriously suggest a current limiting resisitor in the supply lines to each of the three top transistors or even better a constant current source (depends on the number of LEDS you want on in any one branch at a time). The calculation of current is simple if you have only one LED on at a time and due to the high speed switch available with components and the slow decay response of the LED technology this is a practicle solution by strobing the LEDS they will appear to be on at the same time.

     

    Cheers

    Warren

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