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Old 03-08-2012, 02:02 PM   #1
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Default 9093MSPNP Tach output

So ive decided to go with a IGN-4 Coil setup with Diyautotune's Quad spark coil driver, But i have a question about the Tach output. I built the circuit linked below, but for the input do i just tie both ignition outputs together into it? or do i need to make a separate circuit for each ignition output? Thanks for the help guys!
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Old 03-08-2012, 02:53 PM   #2
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That circuit is designed to be driven via a dedicated "tach out" pin of the Megasquirt, unrelated to the actual ignition wires. I'll have to do some digging to see if the MSPnP supports this on the 1.6 model. (Or the folks from DIY will hopefully chime in shortly.)
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Old 03-08-2012, 03:17 PM   #3
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Would the "tach out" pin not be the same as the combined output of the two ignition outputs? It should just be a 5v pulse every time there is a spark right?
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Old 03-08-2012, 04:20 PM   #4
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The Gen 2 has a tach output, the original MSPNP doesn't.

Combining the two 5 volt spark outputs would mean you lose the tach signal once the dwell starts to overlap.
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Old 03-08-2012, 08:32 PM   #5
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Now I'm sad.... Anyway I could add the tach out circuit? Or is my only real option an aftermarket inductive tach?
Could I run the tach off the cas or a trigger wheel? Completely seperate from the ecu?
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Old 03-09-2012, 10:38 AM   #6
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You might be able to run the tach off the CKP pin, but I can't promise it will work.

It is possible, but difficult, to make a tach output circuit and put it in the MSPNP case.
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Old 03-09-2012, 11:10 AM   #7
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this will work:

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Old 03-09-2012, 12:01 PM   #8
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Thanks Brain! I'll have to give that one a try.
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Old 03-09-2012, 02:32 PM   #9
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I'm not sure if that will work, as like Matt said, when dwell periods overlap. I would build the circuit shown in the 1st post.
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Old 03-09-2012, 03:32 PM   #10
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Quote:
Originally Posted by Ben View Post
I'm not sure if that will work, as like Matt said, when dwell periods overlap. I would build the circuit shown in the 1st post.

yeah the first will work, this was just another option.

pretty sure both magnamx-5 and patmx5 are running the one i posted.
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Old 03-09-2012, 06:46 PM   #11
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They are pretty much the same other than the diodes.

Brain, the inputs there (pins 31 and 36) are the standard 5v ignition outputs right?
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