[edc_atl]

Thank you for helping me out. I realy appreciate it.....

Yes I see now that the battery circuit is unneccasary. My thoght was to protect them from eachother if one would get damaged. What will happen if one battery goes bad and start stealing power from the other one? I still would like to have two small batteries for some redundancy. They will only be used for this ignition system, an tachometer and a radio.

Do you have an idea for a simple analog tachometer tu use with the arduino? I would not like to make my code any slower with an extra routine for an rpm signal. Or am i paranoid? Or is there a tachometer with built in logic to put on the one ignintion output pin?

Should I ground everything to the engine case, battery, arduino, other circuits and coil pack?? The coil pack has a ground pin (dont know if it is common ground or just logic ground) and the coil pack is to be grounded with the mounting bolts to the engine case.

The hall sensor: I am using an bipolar hall latch sensor. The flyweel have 2 magnets, one south and one north pointing out. One digital pin has an interrupt routine for falling edge, and the other pin has an interrupt routine for raising edge. So thats why I need to use two inputs. Thats how I know the crank position.

Lets see if we can address everything....

1) You only need a single Arduino Uno for this project, no need for redundancy there.

2) The tachometer circuit you had before was fine to use, just tie it to an Arduino output instead of the Hall sensor.

3) Everyone has a different opinion about grounding, 12V ground should go to the engine case or battery terminal.

4) Hall sensor since it is latching, I believe you can get away with a single input and two routines.

Hope it helps
jb

[Aeroduino]

Ok so here is Version 2.0 of the Aeroduino Ignition system
About the redundancy issue. i think I settle with having two different ignition system on the engine, with two of everything, It makes a pilots life easier

Anyway, I tried to use only one DI and two interrupt routines for the same input pin, but the arduino chosed the last routine all the time, so my system only gave signal to one coil. But it is no big a deal I think, I will jst put a jumper on the pins. I will also set DO pin 13 when DO12, ignPin1 is going high, for the RPM signal.

i don`know yet what to do with the 12v reference signal, I want it to monitor the voltage so that i can get an warning if the battery voltage is low. Or I could just have an Voltmeter conected to it.

Aeroduino Ignition V2.0.png (28.4 KiB) Viewed 5138 times

[PSIG]

Just wanted to mention that dual ignitions are not always for redundancy, but also for efficiency. Note that the rpm drop during a "mag check" might be 125 rpm at 1700 on a Continental or Lycoming 4-cylinder, or 300 rpm drop at 4000 for a Rotax. In either example, the loss of power is about 7.5% allowable, with the other viewpoint being a gain of 7.5% with dual ignition operating under identical conditions. This was the purpose of the USDM Ford 2.3L dual-plug engine, with dual plugs and multi-spark capability, for lower emissions combined with greater power and MPG. Even greater gains can be had if the sparks are tuned with stagger for greatest efficiency (note the offset in many aircraft engine spec's). This helps to explain why not all aircraft systems make sense as being purely for redundancy when you examine them, and that redundancy is often assumed to be the only goal of dual plugs-per-cylinder.

David

[RichCreations]

Just wanted to mention that dual ignitions are not always for redundancy, but also for efficiency. Note that the rpm drop during a "mag check" might be 125 rpm at 1700 on a Continental or Lycoming 4-cylinder, or 300 rpm drop at 4000 for a Rotax. In either example, the loss of power is about 7.5% allowable, with the other viewpoint being a gain of 7.5% with dual ignition operating under identical conditions. This was the purpose of the USDM Ford 2.3L dual-plug engine, with dual plugs and multi-spark capability, for lower emissions combined with greater power and MPG. Even greater gains can be had if the sparks are tuned with stagger for greatest efficiency (note the offset in many aircraft engine spec's). This helps to explain why not all aircraft systems make sense as being purely for redundancy when you examine them, and that redundancy is often assumed to be the only goal of dual plugs-per-cylinder.

Very true! I used to race a flat-tracker with a very highly modified Maico 400 2-stroke engine in it, the compression was very high (ran race gas). Removing the compression release, and fitting a second plug in the hole (a mirror image of the plug hole placement wise) and a second coil, added noticeable power, especially at the top end.

[Aeroduino]

Yes you are so right! I am an aircraft technician and I know that the old mags give quite bad ignition. If there was electronic ignition system available in aircraft in the beginning, there would probably not been dual system. I only wand dual because my Arduino EIS has not been tested and proven enough for me to feel safe yet.
I guess that this vw aircraft engine with this simple EIS will run nice and quite economic

[Aeroduino]

After som help from Noisymime, I have made some important changes. I think it is time to start ordering parts.

Aeroduino circuit V2.2.png (28.81 KiB) Viewed 5083 times

[dazq]

Several years back i followed a series of tests that dave walker of car and car conversion magazine wrote about.
He modified a ford pinto engine to have two spark plugs.this full race spec engine had a very high compression ratio but with a very wild cam needed lots of advance due to flame spread speed at higher rpm when on a single plug.
When he ran twin plugs not only did he need less ignition advance but the engine ran much smoother and made a small power increase.

[Aeroduino]

The tachometer circuit you had before was fine to use, just tie it to an Arduino output instead of the Hall sensor.

Hi Jb.
How do you think the rpm signal should look like? A Symetrical square wave, like going high half revolution and low the other half revolution? Or does a regular ECU tachometer just need a 12V signal as long as the coils are charging? I want to use an regular VDO MC/boat tachometer.
Anders.