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  #201  
Old 08-08-2019, 05:31 PM
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Quote:
Originally Posted by rjcthree View Post
Dan, do you recall how you measure current?
Average, just a Fluke multimeter in series.

Quote:
Iím guessing my setup is showing peak current snapshots.
Me too, but I have not put a scope on it.
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  #202  
Old 08-18-2019, 07:16 AM
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Default It's a Thing

Quote:
Originally Posted by DanH View Post
Sure. This would be the 4-cyl orientation, slip-over-hub style... [snipped]

I took the design DanH's post above CAD'd it up to create a Thingiverse for it. I included my source CAD file too. I went with the under-sized version as that will fit larger as well.

NOTE 1: The 7 small holes on the top are counter-balances for the missing tooth. Their volume exactly matches the missing tooth.
NOTE 2: The alignment of the ring to the flywheel center is very critical. Inside three teeth are small 2mm alignment holes to be filled with pins or screws. These should match the inner lip

https://www.thingiverse.com/thing:3816677

-Bruce
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Last edited by BruceMe : 08-18-2019 at 08:50 AM.
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  #203  
Old 08-18-2019, 07:42 AM
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Quote:
Originally Posted by DanH View Post
Average, just a Fluke multimeter in series.

Me too, but I have not put a scope on it.
I "third" this. You'll need to average the current to get "effective current rate" the battery would see. You could put a $5 5A DC/DC power supply module in front of it (just for measurement) and read what that tells you. It will be smooth.

-Bruce
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  #204  
Old 08-18-2019, 06:46 PM
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Default Messed around, current sensing

I compared the shunt amazon Chinese ammeter/ voltmeter to a Fluke 117 ‘true RMS’ meter. Voltage as right on, current was about a third; the shunt meter showed 4.5A at 2400 rpm, the Fluke 1.29A. This reading includes the coil and the EDIS, but not the Megajolt.

I played with the shunts some more, using a wave form generator I have, and while I can only generate 250ma out of that unit, it’s enough to prove the shunt is displaying 90%-95% peak current of most wave forms, not RMS, and that there is heavy filtering in the frequencies the ignition generates. The Fluke was actually very accurate with its RMS calculation.

My conclusion is that the shunts are only useful for Consistent DC loads. my second conclusion is a 10A circuit is sufficient for the ignition system. From there, it’s about controlling the electrical noise.
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Last edited by rjcthree : 08-18-2019 at 06:59 PM.
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  #205  
Old 08-19-2019, 08:56 AM
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Nice work, thanks!
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  #206  
Old 09-05-2019, 05:57 AM
WingsOnWheels WingsOnWheels is offline
 
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First off, thanks to everyone for their input to this thread. This is a project I plan to take on in the near future. I am going to start with a fixed timing setup to replace the right mag and then go from there, one step at a time.

Stepping a back a number of pages to the topic of run-up testing of the electronic ignition system. Rather than shutting off power to the electronic system and relying on a smooth return to timing. What about grounding the primary coil (just like a mag), but through a resistor to eliminate a current spike. That way the timing circuit is still active and you simply dissipate the spark energy. It should be a smooth transition then.
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  #207  
Old 09-05-2019, 07:24 AM
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Quote:
Originally Posted by WingsOnWheels View Post
Stepping a back a number of pages to the topic of run-up testing of the electronic ignition system. Rather than shutting off power to the electronic system and relying on a smooth return to timing. What about grounding the primary coil (just like a mag), but through a resistor to eliminate a current spike. That way the timing circuit is still active and you simply dissipate the spark energy. It should be a smooth transition then.
Simply interrupting power to the system as a whole (EDIS module and Megajolt/E, coil, everything) works fine if the other ignition system is operating. That means separate toggles. There can be a hiccup if the two ignitions are routed through a left-right-off switch.

The coil has one power lead (EDIS module pin 8 to coil pin 2) and two coil grounds, pins 1 and 3. The EDIS box switches the grounds to control coil current.

You can insert a switch in the pin 8 to pin 2 coil power wire to interrupt coil power without shutting down the EDIS and Megajolt. That approach has been flying without issue. I suppose you could switch to route that coil power to a resistor and then to ground, although I don't see the point; there would still be a spike of some value while the switch contacts are in transit.

However, in addition to system power switching at the panel (which you need anyway), any coil switching adds a wire from EDIS pin 8 back to the panel and then from panel to the engine compartment coil location. It adds component risk for no practical gain.
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  #208  
Old 09-05-2019, 10:26 AM
WingsOnWheels WingsOnWheels is offline
 
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Dan, that makes a lot of sense. I had read about people having blips as the system reacquires timing, but it sounds like that is generally a non-issue. It will require the addition of the toggle in place of the L/R switch, but it is just a minor modification.

I have been researching the possible incorporation of a permanent magnet generator into the mag drive as part of the modification (similar to PMag). Overall, it seems pretty doable so far, but adds mechanical risk. It will be important to incorporate a shear device into the system in case of a mechanical failure. Fun projects all of it....
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  #209  
Old 09-05-2019, 06:33 PM
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Default MJ/EDIS play code / test bench

I think my best decision was to build a bench setup. Itís a pretty steep learning curve with the minimally documented megajolt, especially the two map switch programming. I created test maps just to prove rpm readings, map function, rpm switching, some wiring failure modes, taking data, etc. i really feel pretty good about the risk level. It probably took me twelve to fifteen hours start to finish and $300 of amazon purchased questionable quality stuff to build the thing, not including the power supply, the old PC680 and the MJ.

You might consider starting with a map or two somebody who is already flying has or can make for you and learn from that. Iím sure there are a few of us who would do that for you.

As I plan my install, Iím still not sure Iím going to go with a seasoned EDIS module or a new AM knockoff. Even a 20yo NOS EDIS has risk....
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  #210  
Old 09-05-2019, 08:05 PM
WingsOnWheels WingsOnWheels is offline
 
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I do plan to bench test everything before installation, I hace a lathe that can carry even the flywheel trigger wheel for testing, so the system will have at least some checkout in advance. However, I cant replicate the vibration and heat easily, so it will only be functionally tested.

We do have full vibe, environmental, and emf test chambers at work, but I don't think I could convince them to let me use them.
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