I'm making the circuit depicted here.

I already have the shift registers I require, but I can't find any UDN2981A ICs in the stores I have available to me. Unfortunately, I don't have time to wait for shipping from an online store.

1) Are there alternatives to the UDN2981A I could try? (I've already checked UDN2981A, UDN2982A, UDN2982LW, and A2982SLW, none of them are available)

2) Can I use discrete transistors to substitute the UDN2981A? Which kind do I need?

3) Are there any completely different circuits I could try finding parts for and building?


1 Answer 1


I would:

  • Replace your low-side shift registers with a LED constant current sink shift register like the STP16CP05
  • Do away with all the current limiting resistors - just have the current set resistor for the constant current sink
  • Use discrete (or multi-pack) PNP or P-channel MOSFETs for the anodes, or a high current shift register source (not constant current, just any shift register that can source larger currents).

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