Tris
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| posted on 5/4/11 at 03:58 PM |
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Frequency Multipler for ECU RPM pickup ?
Hello All,
I am currently trying to get my Dash2 display working with my ZX12r ECU, and one of the final jobs to do is the RPM pickup.
The ZX12 ECU has a dedicated (and clean) RPM output, but this has a very low frequency/RPM ratio - 1Hz or pulse is 30 RPM. My dash isn't able
to go down this low, so i need to create some sort of multiplier, ideally x3 (so 3Hz is now 30RPM, or 1 pulses per 10 revs, or 0.1 pulses per single
rev).
Does anyone know of a suitable IC that can triple a given square wave ?
Cheers
Tris
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ChrisW
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| posted on 5/4/11 at 04:19 PM |
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PLL with a 3:1 divider maybe? Or frequency to voltage, 3:1 op amp, voltage to frequency?
Or just use a PIC and be done with it. 
Chris
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Tris
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| posted on 5/4/11 at 04:29 PM |
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Hello Chris,
Yes thought of using a PIC but not used one since uni and don't have any of the programming kit, which makes it an expensive option.
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BenB
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| posted on 5/4/11 at 04:45 PM |
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Yes the simplest bodge is a Hz>V converted, op-amp then V>Hz but your temperature fluctuations will likely be something horrible.
A cheap PIC programmer off Ebay is only about a tenner and some of the new(ish) PICs have a built in PWM so it's not that tricky.
Otherwise a phase lock loop solution but the output won't be that clean.
[Edited on 5/4/11 by BenB]
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BenB
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| posted on 5/4/11 at 04:47 PM |
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http://www.techlib.com/files/ca3028x3.pdf
might be of interest as well though you might have to start adjusting the components (not sure you really need a Mhz frequency tripler).
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matt_gsxr
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| posted on 5/4/11 at 05:13 PM |
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I can't answer your question directly because I am no good at electronics.
If I were doing this I would use the signal from the low tension circuit.
This is the circuit that I have used and worked fine into my Megasquirt. I think that the MS has an opto isolator on its input for safety, although I
have never blown mine it is probably a good idea to incorporate some safety measure (i.e. zener perhaps).
Matt
[Edited on 5/4/11 by matt_gsxr]
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GRRR
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| posted on 5/4/11 at 06:52 PM |
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Try this Link
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Tris
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| posted on 5/4/11 at 08:31 PM |
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Thanks all for your replies. Matt - i didn't want to start going down the route of taking the feed from the injectors because of the possible
noise issues, and the fact i have this nice clean output from the ECU. It might be a plan b though.
GRRR - thanks for the link, ive fired them a couple of questions.
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