COP Ignition Development

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KitCarlson

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I just started working on a coil on plug, or coil near plug ignition system. It will use a modified distributor for timing reference using opto vane sensor and shutter wheel. The sensing method is an improvement compared to a Mopar electronic distributor. I have used an optical system for 12 years in several cars without a problem.

I am presently evaluating the ignition coils. The coils can multi strike at lower RPM, due to the short charge time.

The first picture is the shutter wheel, it will be modified for a sync signal.

The second picture is my 4 cylinder distributor using two optical sensors for a direct fire ignition.

The last picture is my coil test setup. The micro that controls the ignition is at the end of the heatsink under the scope probes. The notebook communicates via USB, to the micro, for setting coil charge duration, spark frequency and counts.

The scope shows the coil current ramp to 8.5A in yellow, the lower blue trace is the ignition primary voltage. The heat sink is for the coil driver with current limit.
 

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Geez Dave. Too bad we are a "world apart." I'd love to invade your "mad laboratory" sometime, LOL

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Lab? I am setup on tray table, watching TV, next to a snoring dog.

I am hoping you move here so we can play electronics.
 
Some guy in the town I was born in just won a million bucks. I don't buy lotto tickets after I found out that, statistically, I'm just as likely to FIND one LOL
 
Del, It likely harder to win a million, than earn a million. But most make a small fortune in racing, by starting with a big one.

More on the COP ignition:
Here are some pictures of the coil. It takes about 1.6 ms to charge the coil to 8.5A, that estimates the inductance at 2.6 mH, and a stored energy of 50mJ. The inductance is less, so the charging is faster, the current is almost double. Since the energy is 1/2L*I*I, energy increases with current squared. Not all energy goes to plug because after about 1 ms the spark goes out. That is viewed on the blue waveform just after the voltage peaks, the clamp voltage at the plug is visible. It is low from the primary view point because of the 61 turn ratio.

When multi strike is used, the spark duration is cut short, by the charge process, it however takes less time to recharge the coil, because the stored residual current. So it takes less time to charge in a rapid fire mode.

Also shown is the COP coil, and without plug terminal. A short plug wire can be installed to use the coil in near plug. This near plug may be the most practical with headers or 273 style manifolds. The small PCB is the micro controller circuit I plan to use. It is what I am using to the test fire of coil. They are now less than $3 shipped.
 

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I have used the Crane Cams XR700 "points retrofit" system w/ optical slot pickup for years. They claimed "0.1 deg accuracy" in the J.C. Whitney catalog. For a distributor-less system, one needs more information to know which coil to fire: at least a crank signal for a "2 cyl/coil" "wasted spark" system, or add a cam sensor for "1 cyl/coil" (GM LS engines, Mopar new Hemi). It appears you are you re-purposing the distributor as a cam sensor (trigger arm where rotor sits).

The Mopar Magnum engines (~1998-2000) use the distributor as a cam sensor, but I think that is just for "sequential fuel injection", since the distributor still distributes the spark from a single coil. The plan for my 273 is to use a Magnum distributor for just its cam sensor to realize a "coil per cyl" setup, but I also have a 36-1 crank wheel (installed years ago, but not used).

Your setup would be a much easier retrofit. The only disadvantage is from slop between crank and distributor, but if you have active spark timing management (knock sensor feedback, etc) that gets compensated as long as you don't see excessive "timing scatter" from too much slop. Simpler electronics than a straight coil is the GM LS coil which has an internal driver. You give it a TTL trigger (plus power) and it fires. They are harder to mount though. GM puts them on the valve covers (coil near plug).
 
I have found a slight spring bias on the distributor drive gear, serves to minimize gear drive backlash. VW used this method in their drives, a simple fix.

While missing tooth gear sensor are more universal, the timing reference is virtual, and are less real-time due to Kalman filter, angle interpolation, and other processing. Updates in RPM occur at 1 or more revolutions.

My system acurately measures RPM on a cylinder basis, and adjusts for rate of change. Timing updates are done at the real leading edge of each cylinder reference signal.
 
I have found a slight spring bias on the distributor drive gear, serves to minimize gear drive backlash. VW used this method in their drives, a simple fix.

While missing tooth gear sensor are more universal, the timing reference is virtual, and are less real-time due to Kalman filter, angle interpolation, and other processing. Updates in RPM occur at 1 or more revolutions.

My system acurately measures RPM on a cylinder basis, and adjusts for rate of change. Timing updates are done at the real leading edge of each cylinder reference signal.

What engine is this? On the V8's many guys used to put a shaft collar --like used on v pulley drives--on the dist shaft to put a bit of preload on things. A spring might actually be better

22040collar.jpg
 
Yep raise collar add spring, avoid wanking, bind and slop. It also reduces wear on bushing by reducing up and down movement. The solid collar may hit high spots, not compensate for expansion with temperature, and contribute to distributor end thrust wear. The spring does not need to be very stiff, adjust pre-load with collar.
 
You might have a winner. I am surprised nobody else has made a COP retrofit, via a re-purposed distributor. COP's would look cool on my slant. It is particularly hard to mount a crank pickup on a slant, so this eliminates that need. You would also need a manifold pressure sensor and probably a user-interface to allow adjusting rpm and vacuum advance. Even if just screw pots, that is much easier than changing springs and weights in a classic distributor.

There was an almost-product, termed "Rabid Gator" that was a "spark control" box for use w/ a GM 8-pin HEI module, but the guy got a better day job and no time to see it thru. I recall TrailBeast has been pinging you for a similar box, but this approach moves it up a big notch.
 
Bill,

The design includes MAP sensor, engine temperature, and battery voltage measurement. The Arduino Nano has a USB connection for use with user interface and code flash.

The outputs will include tach out, to drive conventional single coil tach.

The sync detection via tab wheel has worked well on my 2.2 turbo application with EMS2. The OEM turbo tab wheel with window, is similar, but with Hall sensor. Going to opto costs less, more available and reliable. The change for V8, or 6 is one number in the code. I think I spotted 6 tab trigger wheel to use, but I no longer have a /6 cylinder car. Straight nose coil ends are available, they should work great on slant 6.

I have experience in the hardware and code from my successful EMS2 engine management system. This is a port, to a $3 micro, with less features, but not required, since no EFI involved. The other difference is more coil drive signals. I am still debating if I should overlap coil dwell, not doing that greatly simplifies code design. Even without overlap, the system is capable of more spark energy than conventional single coil w/rotor system.

The ignition coil has a magnet biased core. The bias, increases the inductance, resulting in more spark energy. The dwell time is shorter compared to single coil system. Multi-strike is available at low and medium RPM. I am developing those functions at the moment. I hope to post example in a few days.

I hope to make this design open, so others can build. Perhaps you can assist with the few details, special for the /6 use.
 
I wrote some test code to try multi-spark. The user interface enables the change of coil charge interval, and spark duration. When a spark is stopped by energizing the coil, the retained energy is the starting point, so it takes less time to reach peak current of 8.5A.
The test code on the Nano communicates via the USB connection on PC to a free terminal emulator called TeraTerm. Using the terminal the dwell times and spark durations are easily changed.

I am using a high voltage 1000:1 probe on the blue channel. The peak voltage near 400mV (0.4V) is actually 400V. The upper wave is the primary coil current, viewed via 0.05 Ohm resistor shunt, the 424mV pk on the represents about 8.5A.

A few companies including BWM and Ford are using multi-strike at engine speeds below 1500 RPM. It aids in starting and smoothing idle. BWM starts with strikes.

I may do testing right away by swapping 2 COP coils with primary wired in series for each of the 2 channels in my 4-cylinder waste fire system. If that works, I will make the minor changes in ignition code to go multi-strike.
 

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I think if you're going to get the most out of this, you'd want sequential EFI to go with it. That has made a huge difference for me.

Also shocked you aren't using the LSX "Coil Near Plug" coils which are logic controlled and an easy retrofit, as you mount the coils wherever you want and run a short plug wire. All I had to do was shorten my existing wires.



My car idles super smooth at 900 rpm with a 227/231 duration @ .050 hydraulic roller. It's not even too lopey below that...and the exhaust still sounds good.
 
This system is for carb people. I plan to open the design for DIY, but will not sell kits or parts.

The estimated coil plus driver for my plan is $10 per coil, how much are you paying for LSx per coil? I still prefer two wire coils for several reasons, not involving price. The two wire coil improves trouble shooting, because both primary and secondary voltages can be monitored.
 
This system is for carb people. I plan to open the design for DIY, but will not sell kits or parts.

The estimated coil plus driver for my plan is $10 per coil, how much are you paying for LSx per coil? I still prefer two wire coils for several reasons, not involving price. The two wire coil improves trouble shooting, because both primary and secondary voltages can be monitored.

I bought the set of 8 on EBay for $90 shipped when I got them.

The LSX coil only has a 12V power source, Logic level trigger input, logic ground, and power ground. Not sure how that would change your ability to troubleshoot....With the MS3 I was able to turn them on individually to test them at whatever dwell setting I want.
 
Yes I can drive those coils. My driver circuit is also logic level driven.

My current limit is however adjustable and accessible, so there is greater flexibility, and ability to monitor and control peak current. Setting the dwell for, "whatever you want", without viewing current? Bless your heart.

The ability to measure the primary voltage is also important for me. It is a window into what is happening at the plug. The primary voltage is available at the collector of the driver transistor, that point is not available on the LSx coils.

The coils I am using, have a more advanced magnet biased core, so they are more compact.
 
What engine is this? On the V8's many guys used to put a shaft collar --like used on v pulley drives--on the dist shaft to put a bit of preload on things. A spring might actually be better

22040collar.jpg

Great thread!
Anyone have a pic of the collar and spring setup for a SB?
 
Yes I can drive those coils. My driver circuit is also logic level driven.

My current limit is however adjustable and accessible, so there is greater flexibility, and ability to monitor and control peak current. Setting the dwell for, "whatever you want", without viewing current? Bless your heart.

The ability to measure the primary voltage is also important for me. It is a window into what is happening at the plug. The primary voltage is available at the collector of the driver transistor, that point is not available on the LSx coils.

The coils I am using, have a more advanced magnet biased core, so they are more compact.

Plenty of information about these coils out there. Known as D585's....including the stock tables. Dwelling mine at 4ms at 14V, which seems like it's more than safe enough, and actually slightly less than the stock table. In normal air it sounds like you're using a tig welder. Absolutely no misfiring, and the plugs are totally clean. These coils get swapped on pretty much everything anymore. If the supra guys using crazy high boost and still running a decent plug gap and they're working, I'm sold.
 
At 4ms the peak current will approach 11.7A. The coils will start to overlap dwell (more than one on at a time) above 3100 RPM.

Excess dwell is detrimental, the driver transistor avalanche protection clamps the peak voltage, that means undesirable dissipation in transistor. Since the secondary voltage is the turns ratio times the primary voltage, it too is clamped. That is why being able to view the transistor collector voltage is important to me. The LSx coils have that point internal, no way to get there.
 
Here is a picture of the signal from an Arduino Nano, that is programmed as an ignition simulator. In the development process a distributor simulator provides signals that would be available from a spinning engine. The simulator changes the RPM up and down. A logic analyzer captures the simulator signal and the ignition system control signals. Things like dwell and timing are accurately verified by measuring signal timings.

The tooth with notch is the reference tooth. It is decoded by the fact the narrow teeth are less than the normal tooth width. The micro measures rise and fall widths, and uses the information on a cycle basis to measure RPM. RPM is used in the process of generating the timing based on control tables. More will be written about that at a later time.

The tooth edges are used in the timing control. The leading edge is the is maximum advance, the trailing is base timing. The width of the controlled timing is 45 degrees, the based timing is added to that.
 

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Here is a picture of a spring for slight thrust preload of shaft. I purchased the spring from a drawer at hardware store. I also found 1/2" ID collar, but it is not required.
 

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Here is a picture of the signal from an Arduino Nano, that is programmed as an ignition simulator. In the development process a distributor simulator provides signals that would be available from a spinning engine. The simulator changes the RPM up and down. A logic analyzer captures the simulator signal and the ignition system control signals. Things like dwell and timing are accurately verified by measuring signal timings.

The tooth with notch is the reference tooth. It is decoded by the fact the narrow teeth are less than the normal tooth width. The micro measures rise and fall widths, and uses the information on a cycle basis to measure RPM. RPM is used in the process of generating the timing based on control tables. More will be written about that at a later time.

The tooth edges are used in the timing control. The leading edge is the is maximum advance, the trailing is base timing. The width of the controlled timing is 45 degrees, the based timing is added to that.

See that's the difference between us, LMAO. I would have to screw around and rig up a distributor to generate that through a mockup system
 
Here is a picture of a spring for slight thrust preload of shaft. I purchased the spring from a drawer at hardware store. I also found 1/2" ID collar, but it is not required.

I'm going to have to try this. There is one downfall............you would want to be careful next time you yank out the dist, because if you "forget" that spring could do bad things
 
I'm going to have to try this. There is one downfall............you would want to be careful next time you yank out the dist, because if you "forget" that spring could do bad things

I think you could captivate the spring with a hole and roll pin, or groove with a C-clip.

About the simulator. It only took a few minutes to write the code. Once things are debugged, I move on to distributor and variable speed drill.

I have been re-thinking things and may go to a two sensor distributor. The plus is the second sensor input could be used on crank sensor. The distributor sync sensor per 1/2 rev, like used on some magnums would serve as cam sensor. The plus is timing would be crank based, and the sync sensor would sync in one engine rev not two.

I think similar could be used on 8, 6, and 4 cylinder engines, with 8, 6, 4 tab wheels.

Below are the lines of code for the important parts of simulator.
The most basic part of the design is to think of the signal to be generated as edges where the signal goes from 0 to logic 1, and the time between them. I defined the "times" as number that are the lowest denominators. The "times" are multiplied by a variable named "period" the larger the period the lower the RPM. The main part of the code changes the period to change the RPM so it ramps up and down.
 

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