Working on ignition system controlled by prehistoric ECU, it has 2 signals: select and trigger. Select switches CoilA and CoilB. Trigger controls dwell time.

I want to purge old broken coils and install modern ones with integrated ignitors. So need to convert select/trigger signals (0..5V) to 2 direct outputs for each smart coil (0..5V). The power applied via different inputs so these signals can be considered as logic only.

That can be easy done with a few general purpose logic elements, but I feel this is very common case in electronics and there should be simple existing solution (simple -> single chip).

Any ideas?


  • 2
    \$\begingroup\$ What's simpler than using logic? \$\endgroup\$
    – Andy aka
    Sep 20, 2019 at 12:27
  • 1
    \$\begingroup\$ You could implement the logic using transistors instead of logic IC's. Is that what you're asking? That may be interesting if the supply voltage doesn't fit the supplying requirements of the logic IC's or when the IC's fail to drive the coils directly. But then, you need to provide all this info as well (not in comments, but by editing question) \$\endgroup\$
    – Huisman
    Sep 20, 2019 at 12:38
  • \$\begingroup\$ Welcome to the site. You need to edit the question and add more details, such as the input signal voltages and the output voltage and max. current. \$\endgroup\$
    – TonyM
    Sep 20, 2019 at 13:06
  • \$\begingroup\$ ...and max. output current. \$\endgroup\$
    – TonyM
    Sep 20, 2019 at 15:34

1 Answer 1


I think the solution you're after is a de-multiplexer (or demux) like one of these with some buffering on the input and output to handle voltage level shifting and line driving. The select line is the 'address' and the trigger line is the 'data' which you want to route to one coil or another.

In reality, an integrated demux is only 3 gates. 1 NOT, 2 AND or not many more if you want a pure NAND implementation. So it's not saving you a great deal but i think it's the solution to the common case you're thinking about.


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