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Active State - High Pull-up Voltage 12v Pulses per cycle - 0 Tach needle sweep RPM - 8000
haltech tech was very helpful and offered to do a remote connect to have a play but my work hours has overlapped with their hours so far this week.
"Basically the ECU just needs to provide 12v power and the coil provides the negative signal to trigger." - I suspect that when the signal from the coils is in phase with the output from the haltech, I get correct RPM, then for some reason it ends up out of sync, and the haltech and the coils are both feeding a pulse out of phase with each other, and I get double rpm, or something wacky. Either way, working now and very happy. Now to get onto the AC. I think I can see a sticky thread coming at some stage with each topic holding settings for various things that once sorted can be shared.
Haltech recommended I use their tach output. Said if it doesn't work, I can return it. We'll see. I did scope tach output...it is a square wave, but I noticed the peak to peak voltage was not 12v. More like 8-10v under the low, 12v pullup settings.
So, in sum, my 94 Miata's tach does not take a strict square wave signal. Instead, it takes a squarish signal with a notable spike on the rising edge. From the Haltech documentation, this signal is used by "coil negative driven tachs". All signals were verified with a oscilloscope.
I set the ECU to low, 12v pullup and 4 pulses + the adaptor.
Care to elaborate? I guess I'm just not thrilled at spending a $100 for something like this assuming (minus the fancy plug/pins) this is probably $10 worth of electronics.
Well, my understanding is that the trubokitty resistor is used as a pull up. The Haltech box changed the shape of the signal, because as I mentioned in a prior post, I still had to use the internal pullup to make the tach work.
I'll add that...if you can build this yourself, more power to ya.
Yeah I suppose just trying to work out how to get this working in conjunction with wiring/installing some R8 coils. To clarify, you tried msmola2002's settings and they didn't work?
https://www.ebay.ca/itm/142171581596 This was recommended in the Haltech FB group from a guy with a 280Z, it converts the tach signal from square edge to the voltage spike leading edge, same as the haltech adapter box, It is a fraction of the cost but it is outputting the spike to something near 60v - and I don't want to be the guy that tests it to find out if it nukes my tach or not, since I already put my revlimiter faces on. I will end up in this same situation no doubt when I go to my LS coil setup, and not being an electrical engineer I will probably pay Haltech for their module unless someone else plays sacrificial lamb with one of these things first.
The comic sans also instills nothing but pure confidence.
Nice! Will be interesting to see if the haltech spike is only a few volts, or if it is a similar big 50+v discharge like the comic sans box. Because if it is, at the price you can afford one and the douche connector and still be at half the price.
Thanks man that would be sweet! I'm sure this is a relatively simple circuit, I'm just way more on the mechanical side of life in terms of background ¯\_(ツ)_/¯.
That said I do have a analog circuit designer buddy that owes me a beer. If you can get me some data on the waveform I'd be happy to do a run of 5 or 10 PCBs for yall...Minimized china parts of course...what an ad....
Edit: looking through the docs you could probably just mess with the input voltage to the circuit to change the peak on the rising edge, probably not worth doing our own PCBs at this price...
Originally Posted by Socals14
Nice find! I have an oscilloscope, so I should be able to measure the spike...perhaps this weekend I can get some data for you.
Last edited by Spaceman Spiff; Apr 22, 2021 at 01:25 PM.
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