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Megasquirt Tach Signal
liam.mccaffrey - 8/7/09 at 10:36 AM

What does the MS tach output signal look like, is it pulsed or analogue?

Many Thanks

flak monkey - 8/7/09 at 11:23 AM

Its a 5 or 12v square wave depending where you pick your power up from.

I used this diagram

http://www.msextra.com/manuals/MS_Extra_Hardware_Manual.htm#tachoout

With two 1Kohm resistors and picked up the power form the S12c point on the board.

David

[Edited on 8/7/09 by flak monkey]

Jenko - 9/7/09 at 10:54 AM

David, did you use this method to power a VDO rev counter?....I can't seem to get mine working...

flak monkey - 9/7/09 at 11:23 AM

quote:
Originally posted by Jenko
David, did you use this method to power a VDO rev counter?....I can't seem to get mine working...


No its powering a digital dash designed to take a square wave signal.

You might need to generate a high voltage spike if its a VDO tacho designed to be driven from the neg side of a coil. There is another diagram on the page linked above to do just that.

Jenko - 10/7/09 at 08:42 AM

I tried that other method but could not get it to work...that said...I didn't try too hard, as I run a digital rev counter also, but I want to get rid of this and go back to the VDO...

Cheers for the link anyway.

Paul.