Abe & JasonC's NB Cam & Crank input circuits - Page 4 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 01-16-2009, 11:31 AM   #61
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An opamp/comparator Schmitt trigger circuit (yes an opamp with all those resistors configured that way is called a Schmitt trigger circuit), can be designed to have a wider "hysteresis", and thus more noise rejection, than a one-chip Schmitt circuit like the CD40106.

Or, as Abe put it, they may have had 2 spare opamps sitting on the board already...
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Old 01-16-2009, 03:11 PM   #62
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Can anyone post a finalized schematic of the said input circuit. I've read through the circuit and while I have a good grasp on things here, I can't decide on which schematic would work best for an NA.
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Old 01-16-2009, 05:55 PM   #63
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Jason: Thanks for clearing that up! I always thought they were more complicated (or less, depending on if you consider an opamp to be complicated or simple).... I guess you could just try it and see, though I would be tempted to stick the with OEM values unless you want to test it to oblivion.


I forget who asked, but: I think all the op-amp circuits posted are equivalent. So they are all the final version, just drawn different. If it's the best input for an NA, I'm not sure... Should work well though.
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Old 06-19-2009, 04:47 AM   #64
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Hope this alternator thing works. :-)

Anyway, obligatory teaser:
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Old 06-19-2009, 06:23 AM   #65
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I want one! Now!

P.S.: Has it also got the alternator control thingy (Jasons circuit) ?
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Old 06-19-2009, 07:14 AM   #66
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I would imagine as there's a nice big 100F capacitor on there
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Old 06-19-2009, 07:20 AM   #67
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Maybe this gets you also back in the game, Frank?!
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Old 06-19-2009, 04:14 PM   #68
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Abe, would those TO-22 transistors require some sort of heatsink?
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Old 06-19-2009, 04:51 PM   #69
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Quote:
Originally Posted by AbeFM View Post
Hope this alternator thing works. :-)

Anyway, obligatory teaser:
It's mine!!! I hope the alternator will work too!!! Turbo is here too. Gonna be a busy July for me!!!
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Old 06-19-2009, 04:53 PM   #70
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Good lord! Talk about lots of interest. Well, it's supposed to be a teaser, since I haven't actual run it yet, but with the exception of the included (good spot on the cap! Unfortunately it semi-blocks some of the jumper labels. I might mount it on the back of the board next time) alternator control (Thanks Jason!) it's all stuff I've build multiple times before and I know works.

To answer some questions:
1) As a backup, there's a line out to use the Mopar alternator control box as I've done on my car. Seems the success rate with that is about the same as with Jason's - 50% over all, 100% when done by the person who first came up with it. :-)
2) WBO2, Knocksense MS are both handled by the board, both in terms of providing switched power and raw signals out, as well as receiving signals back in. All this is done on the terminal blocks. (For additional reliability, solder wires to this instead, but it's less flexible)
3) I'm pretty sure they will need heat sinks. I haven't decided if I should get the little extruded ones and put them on separate, or a bar and insulators.
4) The row of jumpers in the middle will allow the tinkerer to break any signal, inspect or modify it. Also useful for rerouting for different years. I have one pin used as VVT out or a spare, and a clutch switch in. For a slightly more reliable solution, just soldering wire across is the way to go.
5) The board is designed to use a stock MS-II. Only a few wires would need to be changed, basically stuff to bring out the right spare pins, and bypass the majority of the MS's (very poor) inputs. The idea was you'd buy an assembled MS, run ~4-10 wires, but no resistors, diodes, or anything else, and plug it into this board and be good to go.

Other background questions I've seen: Yes, it's for full standalone. You can use the spare line to control the purge solenoid if you want - for emissions, or as an idle adjust as some have done/suggested for AC compensation. The biggest issue most NB people are finding is the input circuits, this incorporates almost exactly the OEM inputs. If you really want to rev very very high, you might leave the caps out.

If I get enough interest, I'll probably buy a stack of the OEM connectors, when doing my boomslang, those f'ing connectors and their shipping was like 20% of the whole MS project.


Lastly: TeamPlur can help me out as he has a fairly stock 2000 miata, but I would be very interested in finding a like minded SoCal person who would like to let me plug this into a car with a stock wiring harness and see how it all works. I figure I'm a few days to a week away from having the MS ready... Once I get a parts list together (instead of built out of scavenged parts like this one was) I'll be able to find some pricing for both "kits" and assembled units. Likely I'll be able to have people send me a pre-built MS, mod it and send back a 'turn key' where all they have to do stick the boost control soleniod wires in and call it good.
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Old 06-19-2009, 05:08 PM   #71
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Default To keep the threads seperate!

Started a new thread, I wasn't thinking I'd get so much attention.

https://www.miataturbo.net/forum/t36300/

That's for talking about the adapter board. Now we can keep this thread for discussions in inputs only!
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Old 06-21-2009, 04:15 PM   #72
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Quote:
Originally Posted by Zaphod View Post
Maybe this gets you also back in the game, Frank?!
Nope, I'm forgood out of the game. I bought an oscilloscope to test my MS and it turns out to be 100% funtional on all circuits.
So I must have a wiring problem in the car (this is going on a kitcar, not a miata) or maybe (don't think so) a software setting in the MS.
No one on this forum cared to share a msq, so i can't be bothered with it any more.
I have decided to completely abandon the turbo project and sell the megasquirt. I'm staying on the oem ecu, non-turbo.
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Old 06-22-2009, 04:22 AM   #73
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I never sent you any MSQ?!?! I thought I had. Email me, you have my email? I'll get one out today or tomorrow. I had big problems with little things like inverted input signals, etc, all software settings.

That, and start up stuff.
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Old 06-22-2009, 08:38 AM   #74
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thx Abe, much appreciated.
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Old 05-09-2010, 06:45 PM   #75
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I have these two circuits for my Cranks and cam inputs currently:

Crank


Cam


The two circuits use an optoisolator but I'm not great on electrical circuit design... why wouldn't these work with the MK2 crank and cam sensors?

They work brilliantly with CAS signals...
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Old 05-09-2010, 08:11 PM   #76
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Quote:
Originally Posted by richyvrlimited View Post
I have these two circuits for my Cranks and cam inputs currently:

Crank


Cam


The two circuits use an optoisolator but I'm not great on electrical circuit design... why wouldn't these work with the MK2 crank and cam sensors?

They work brilliantly with CAS signals...
IIRC, someone said the stock inputs on the Megasquirt have too much noise to accurately process the signals from the NB sensors, hence the reason for the different circuit.

The miata's CAS is a pretty simple wheel to decode, in comparison to the NB models, which use a more complex pattern.
I
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Old 05-10-2010, 10:27 PM   #77
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More or less correct - it's not the complexity, but the noise. The NB sensors are just kinda ugly. The circuit everyone uses now for NB's is literally Mazda's design.

In a nutshell, the op-amp circuit ignores any signal shorter than some tunable length - so a bit of "static" just gets pulled right out. It's pretty elegant, I think. :-)

Of course, if wiring is your thing, try it and see - it's not that it won't work, it's that you'll get a rough ride when sometimes it misses a signal. A skip here and there - if it's so often the motor won't run, or once a month, depends on a lot of hard to predict factors.
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Old 05-11-2010, 05:24 AM   #78
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Quote:
Originally Posted by AbeFM View Post
Of course, if wiring is your thing, try it and see - it's not that it won't work, it's that you'll get a rough ride when sometimes it misses a signal. A skip here and there - if it's so often the motor won't run, or once a month, depends on a lot of hard to predict factors.
It's more the inside of my MS case is a nightmare with the proto area full and a 4 channel driver board making is a PITA to take apart.

I'm older and more wary of fixing something that isn't broken, but VVT control has a strong pull....arrrgh.

Think I might make those circuits of yours on a spare breadboard to simplify the change...
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Old 05-12-2010, 08:29 PM   #79
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OK sorda an idiotic question but I want to be 100% clear before I mod my board

My setup is:
96 miata
MS1 running hires 10g code
Parallel harness
NA CAS obviously
Currently have "missing" issue a few people have on highway cruise. Does not happen on stock ecu. Added grounds / ect... now I want to improve the input circuit

Questions:
1) Is the diagram stated in post #1 the diagram I should use for my NA ms1 setup
2) The original miata mod has TachSelect to OPTIN. I need to change that to Tachselect --> new circuit ---> TSEL, correct?

3) Does TSEL still go to OPTOUT
4) I remove the original pullups and "cap mod" on IAC1A and replace them with the circuit , correct?
5) This works fine with Hi-res and does not require further caps?
6) Does anything need to be changed in the .msq, config, or general software stuff?


Thank you. I know these may be simple but I want the expert to tell me.
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Old 05-12-2010, 10:41 PM   #80
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Quote:
Originally Posted by 240_to_miata View Post
Questions:
1) Is the diagram stated in post #1 the diagram I should use for my NA ms1 setup
2) The original miata mod has TachSelect to OPTIN. I need to change that to Tachselect --> new circuit ---> TSEL, correct?

3) Does TSEL still go to OPTOUT
4) I remove the original pullups and "cap mod" on IAC1A and replace them with the circuit , correct?
5) This works fine with Hi-res and does not require further caps?
6) Does anything need to be changed in the .msq, config, or general software stuff?


Thank you. I know these may be simple but I want the expert to tell me.
1) You can use Abe's circuit on the first post, OR you can use Jason's Schmitt trigger circuit. Jason's circuit ha a lower parts count, if that sounds more appealing to you.

2) Yes, you would out the TACHSELECT pin straight to the circuit then you would put that out circuit pin straight to the TSEL pin.

3) No, you skiip the stock MS input circuits completely. You wouldnt even touch those, and you wouldnt even need to install the inputs circuits that are listed on the megamanual.

4) Yes, you will be removing any other circuit mods you did, all the pull ups, and what not. Well, except for the spark outputs. Those dont change.

5) Not sure, but I woujld assume so. That "cap mod" is just a mod to filter out noise IIRC.

6) Nope. You arent doing anything to change where the inputs go for circuit, so no you wont be changing anything that is software related.

Hope this solves all your problems. Good luck!
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