4strings

iTrader: (1)

Hi All,

I know that Joe's "A Better Spark Out..." thread just got brought back from the dead for no apparent reason. I have been following the MSExtra Manual and it says using this MOSFET IC that seems to mimic Joe's "double inversion circuit." I read that whole thread and a few others but I have a question about an option in the MSExtra manual

TC4427AEPA Microchip Technology | TC4427AEPA-ND | DigiKey]Invalid Request


I'm building DIY MS2 V3.0 to run my stock '94. Going for stock ignitors and wasted spark for now. If I prove successful (getting it running & tuning it), I'll be moving to COP.

The MSExtra Manual (5.3.1.3) states that with this logic coil spark circuit, "Coils do not receive a spurious signal pulse at power on", which leads me to think it behaves similarly. However, looking at the details on Digi-Key, it states that the Input Type is Non-Inverting. This confused me (as if the whole "spark inverted" thing within TunerStudio wasn't confusing enough.)

I admit that I don't have as good a grasp on electrical systems as I aim to achieve in the future. As it is now, I can't make much sense of the circuit diagrams that show the internal workings of the IC to verify that this will have the same effect as Joe's Better Spark Out Circuit (grounding the circuit when inactive and inverting what the CPU outputs to the coil)

http://www.microchip.com/mymicrochip...cname=en011753

Even searching for "4427" turned up with nothing relevant here and surprisingly few relevant results even Googling (like 5). I realize which end of the scale of expertise on this subject I fall towards. Just hoping for some clarification and a learning opportunity. Thanks.

4strings

iTrader: (1)

So that people don't have to go link hopping, this how the MSExtra manual shows to wire up the chip:




And this one that is from the IC's data sheet showing how it works on the inside:

Braineack

iTrader: (62)

build a ms3x and dont ever think about this stuff.

4strings

iTrader: (1)

Thank you Braineack. The MS3X may be an option in the future but presently, I am interested in this chip.

I am realizing as I learn more about the MegaSquirt, how it has been adapted to fulfill many capabilities it was never originally designed to handle.

Ben

iTrader: (33)

The TC4427A circuit wasn't put in the manuals until recently.

I'm failing to find your question though.

Braineack

iTrader: (62)

it appears it'll work as you intend.

ive never seen these in use, it's very new to the documentation, but im assuming it's more or less similar to the IC they use in the Expander board for spark outputs.

Ben

iTrader: (33)

The TC4427 has higher source current ability than the drivers on the expander. It's a good little IC.

4strings

iTrader: (1)

Ben, good to know that the chip should be able to perform.

The question is will this chip invert the signal from ecu like Joe Perez's Better Spark Out Circuit; hopefully preventing pop on cranking and protecting the ignition coils when flashing.

Thank you Braineack. So the output option in Tuner Studio will also mimic Joe's as "spark output = inverted"?

MiataFox

??? on Joe's "A Better Spark Out are the led on all the time or turn on when the spark happens or do i have some thing not wired right ?? i test the spark in tuner and it works but dose not of the trigger for it . and its is taking for ever to fine stuff and pic are missing can we get them back up

4strings

iTrader: (1)

MiataFox, This is my first rodeo, therefore I wouldn't consider myself an expert. If I were you, I would create your own thread about the unique problem you are experiencing complete with a detailed description of your build and pictures as well. You may get a better response that way. As a side note, both the comments you've left about this were difficult to read in their own rights (grammer/spelling).

Did you test your spark outputs before you did the Better Spark Out? Since this circuit is triggering your ignition coils, I'm inclined to think that they should not be solid on.

Ted75zcar

iTrader: (2)

Based in the functional block diagram this circuit should invert. The input clamp prevents back drive. The mosfet conducts when the input is high. The current source shorts when the mosfet conducts. The schmitt trigger inverts, fillowed by another invert, and then the totem pole. This is from memory, can't see the diagram while posting, and I am too lazy to open another window. Three inverts => inverted output. Totem pole => push-pull (source-sink)

Edit: I just reviewed the data sheet as well as the digismack page and I can see why you are confused. The timing diagram looks like you need the 26 for an invert. I would suggest that you buy the dual(28) or both the 26 and 27 and bench test.
Additional corrections: the totem pull is another invert, and I misremembered the configuration of the input zener, it provides input reverse polarity protection.
F, it is late. I should just keep my mouth shut.

MiataFox

I have and the guys that know this stuff i guess do not like me ... for i have had no help at all and they will not fix there old post that say look at the pic below and the pic gone .

i'm going on what i have found but its just parts of post . and i know my grammar is not the best and i use spell check .. what can i say i'm more in to cars then writing books but thanks for the help

4strings

iTrader: (1)

If you post 2 more times, i can PM you and may be able to help at least a little.

4strings

iTrader: (1)

Miata Fox,

Maybe this will help?

http://miataturbo.wikidot.com/ms2-a

MiataFox

i have that and it is not complete ie jumper and other stuff

MiataFox

but this is what i'm talking about nothing is complete the harness he shows is not right for that set up at less not all of it for the 91 miata

4strings

iTrader: (1)

The spark circuit tho looks right. You can set up the harness however you want, but this will get spark out to your igniters and it looks like Joe's circuit.

Matt Cramer

This circuit has the same input / output characteristics as Joe's circuit. It will not attempt to dwell the coil until it receives 5V from the processor.

MiataFox

i do get spark out but i'm not getting trigger to trigger the spark my ms2 is set up that way but is still not working so some thing has to be missing my led are on all the time and i think they need to be off ?

and i set it up brain way and it still did not work but still put out spark if i use the test in tuner

so what e'm i missing ????

Braineack

iTrader: (62)

LEDs are always on in Joe's method.