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 Post subject: Measuring tacho wave signal
PostPosted: Tue Sep 04, 2018 9:59 am 
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I Say: There's no 'i' in Team, but there is in Winner!
Vehicle: MY10 XT

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Has anyone conected an oscilloscope to the tacho signal wire. I need to know the details of the pulses falling edges so we can write the code for the arduino.
I thought I’ll ask first, if not i’ll bring home an oscilloscope and check it myself.


Last edited by Tobyo on Tue Sep 04, 2018 6:06 pm, edited 1 time in total.

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 Post subject: Re: Tacho wave signal
PostPosted: Tue Sep 04, 2018 5:15 pm 
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Vehicle: JDM SF STi Pure White

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Location: Germany
Oooh, i'd also love to see that, mostly just for **** and giggles.

What are you planning to do with the arduino?


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 Post subject: Re: Tacho wave signal
PostPosted: Tue Sep 04, 2018 5:44 pm 
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I Say: There's no 'i' in Team, but there is in Winner!
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Im using the Mega coupled with a TFT 800x480 screen to run the water spray. It will do a few other bits such as trigger a shift alarm at the selected RPM, monitor the water tank level, use a MAP sensor as the pump trigger, monitor two air temp sensors on either end of the TMIC tanks and a few other little tasks.
The screen and panel will mount in the cubby below the HVAC controls

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 Post subject: Re: Measuring tacho wave signal
PostPosted: Tue Sep 04, 2018 6:31 pm 
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Its a low side square wave pulse.

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 Post subject: Re: Measuring tacho wave signal
PostPosted: Tue Sep 04, 2018 7:06 pm 
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Vehicle: JDM SF STi Pure White

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Daaamn, that sounds nice.

I sure hope you're documenting it somewhere, that's the kind of thing i've been thinking about doing.

What temp sensors are you planning on using for the TMIC temps? I've been looking around the net for some and i figured the regular temp sensors (the ones used for oil/water temp) won't be any good because of the thermal mass they have. They'll simply be too slow to show changes in air temperature.


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 Post subject: Re: Measuring tacho wave signal
PostPosted: Tue Sep 04, 2018 11:44 pm 
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I Say: There's no 'i' in Team, but there is in Winner!
Vehicle: MY10 XT

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Location: Mealbun Orstraya
Bram wrote:
Its a low side square wave pulse.


The guy doing the programming said he needs to know the peak voltage and the drop across the pulse.

I bought three haltech IAT sensors. One will go between the intercooler and throttle body. The factory MAF wire will then be repurposed. Each of the intercooler IAT’s will have a potentiometer so i can precisely dial them in.

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 Post subject: Re: Measuring tacho wave signal
PostPosted: Wed Sep 05, 2018 5:22 am 
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Hm...Wouldn't it have been easier to dial them in in software?

Damn you, you give me ideas and stuff to spend more money on.


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 Post subject: Re: Measuring tacho wave signal
PostPosted: Wed Sep 05, 2018 7:55 am 
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I Say: There's no 'i' in Team, but there is in Winner!
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The key word is “precisely” :lol: .. The potentiometer allows us to get it exactly. As you probably know, the IAT is simply a resistor. Grab a handful of resistors and measure them with the multimeter and you’ll find a small variation across them. Over time I assume the resistance will slightly change and it just means I can give it a tiny tweak to bring it back in line. Or you could put an offset into the code. Either either


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 Post subject: Re: Measuring tacho wave signal
PostPosted: Wed Sep 05, 2018 9:17 am 
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Tobyo wrote:
The key word is “precisely” :lol: .. The potentiometer allows us to get it exactly. As you probably know, the IAT is simply a resistor. Grab a handful of resistors and measure them with the multimeter and you’ll find a small variation across them. Over time I assume the resistance will slightly change and it just means I can give it a tiny tweak to bring it back in line. Or you could put an offset into the code. Either either





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