How do these electronic ignition kits work?

turbofiat124

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I've always wondered how these systems work:

http://vkakarting.com/replacing-points-with-ignition-module/

So when the points close, the - post on the coil becomes grounded and discharges the stored energy through the coil wire to the spark plug. So when using this module, how does it know when to fire the coil?

I know how magnetic triggered electronic ignitions work (like GM HEI). A magnetic star (or magnet itself, example Petronix Ignitor) passes by a transistor than turns on and off. But with this device, you just snip the wire going to the points and connect it to the coil.

According to the article, it says to verify the timing and adjust the coil accordingly? I never really put much thought into it but I always thought the timing was fixed on most if not all small 1 cylinder engines.

I installed one of these on an old B&S engine with points I was having a tough time getting started but can't remember if it worked or not. Seems like it did but the engine had other issues. That was 25+ years ago. I ended up pulling the engine off the mower and replacing it with a larger displacement engine with electronic ignition. So I can't remember. It's still in my parent's barn.
 

bertsmobile1

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They are called Hall Effect triggers and were invented down here by a couple of Hungarian imigrants in the late 50's.
They were Husqvarna agents and sold developement rights Husqvarna and also marketed the units themselves as the ATOM Ignition Module.
It is the same Atom company that still makes the best garden edger ever designed, the Atom Edger, although the local big box stores have flooded the market with an identical looking inferiour Chinese copy for 1/3 the price so they might not be around for much longer.
You can look them up on the web if you like.
I think the whole story and a full explaination of how they work is up there.
And just to make you feel sour, back in the 60's the card & blow moulded package cost more to make than the module.

As the magneto magnet passes the coil, a voltage is induced.
However it starts at 0 V then rises to a peak before dropping back to zero.
The module measures the voltage and when it gets to a set value it closes the circuit for the coil ( same as points ) then opens it to allow the maximum spark to occur.
The voltages it measures are in the micro volt range which is why you fry them when you connect them to the battery by accident.

The early ones had fixed timing but the latter ones had built in advance curves.
Every now & then you will still see an Atom come up for sale and they were colour coded according to the advance .

And while we say advance , what is really happening is less retard
Down here Victa took them up strait away and made them standard which is why the power torque was such a good engine and way way better than anything else till the 90's by which time the patients had expired and all the other small engine makers fitted their own version.

We used to fit the purple ones to racing Bantams and for $ 15 got an ignition that never missed and would run the engine up to 15,000, yet had enough retard to allow a Monza push start.
 

turbofiat124

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Excellent explanation! That makes perfect sense.

I hate to mix apples and oranges but one reason I thought of this device was I was wondering if it may work on a car. However after you explained how the module works, I doubt that it would. You mentioned that if you connect it to 12 volts it will fry the module. So in a small engine, the coil is energized by an magnet in the flywheel, every time the flywheel passes the coil. Where as on a car, the coil is powered by battery voltage. Correct?

Are you familiar with wasted spark ignition systems?

My Trabant uses 2 sets of points and two ignition coils. One set for each cylinder.

6e22417756f8fabd6457dd83f2f75694.t00000175_b1.jpg


My Citroen 2CV also has a 2 cylinder engine (but a four stroker) and uses a wasted spark ignition system. I have an ignition coil from a Harley Davidson on my 2CV with two plug wire outputs.

I wondered if this type of system would work on a 2 stroke engine and after doing some research it has been used on other 2 cylinder 2 stroke engines.

I was not happy with the aftermarket electronic ignition systems on the market.

6573ba5aee9fcd8fa6a07a294c4dddfc.t00000722_b1.jpg


First of all, the points lobe is oblong instead of square like most points system so when the plastic ring slides over the points lobe "easily", the coils fires after top dead center so in order to get the timing closer to TDC, the ring has to be forced onto the lobe.

Also the circuitry is mounted on the board which means if you accidentally touch something with a screwdriver with the ignition switches on it will short something out. Well guess what, I shorted out one of the transistors doing just that. My mistake but the components are vulnerable.

Then there is cost. Shipping from Germany is quite expensive. A replacement unit would cost around US$ 170. That's including 30 Euros for shipping. You can buy a Hot Spark ignition system + free shipping just for what it costs in shipping from Germany.

So I decided to build a better mousetrap. I used a Hot Spark system for a VW Type 1 and I am firing both coils simultaneously.

Here is a video in the testing phase.

https://www.youtube.com/watch?v=LvllaO908p8

I'm in the process of refining the system. So this is not the final result.

One of the biggest challenges was trying to figure out where the transistor was located in the module in order to just get the engine started and running. I painted some reference marks above the magnets. Using a timing light shows the magnets are positioned at the leading and trailing edges of the module. Then through trial and error finally got it the ignition spot on.

My only concern is these Hot Spark systems are finicky. The instructions says anything above 13.7 volts will cause the module to overheat. So they recommend a ballast resistor to drop the voltage if this is the case. And also not to use low resistance ignition coils. So there has to be some tests conducted to make sure the module is compatible with the coils.

My concern is will firing two coils simultaneously cause the module to fail? I'm keeping the breaker points in the trunk and will be prepared to throw it back on in case the system fails.

The Petronix Ignitor does not seem to care. My suspicion is the Pertronix Ignitor has a built in regulator to avoid spikes. That may explain why a Petronix system sells for twice as much as the Hot Spark systems.

Any thoughts on this welcome!
 

BlazNT

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They are called Hall Effect triggers and were invented down here by a couple of Hungarian imigrants in the late 50's.
They were Husqvarna agents and sold developement rights Husqvarna and also marketed the units themselves as the ATOM Ignition Module.
It is the same Atom company that still makes the best garden edger ever designed, the Atom Edger, although the local big box stores have flooded the market with an identical looking inferiour Chinese copy for 1/3 the price so they might not be around for much longer.
You can look them up on the web if you like.
I think the whole story and a full explaination of how they work is up there.
And just to make you feel sour, back in the 60's the card & blow moulded package cost more to make than the module.

As the magneto magnet passes the coil, a voltage is induced.
However it starts at 0 V then rises to a peak before dropping back to zero.
The module measures the voltage and when it gets to a set value it closes the circuit for the coil ( same as points ) then opens it to allow the maximum spark to occur.
The voltages it measures are in the micro volt range which is why you fry them when you connect them to the battery by accident.

The early ones had fixed timing but the latter ones had built in advance curves.
Every now & then you will still see an Atom come up for sale and they were colour coded according to the advance .

And while we say advance , what is really happening is less retard
Down here Victa took them up strait away and made them standard which is why the power torque was such a good engine and way way better than anything else till the 90's by which time the patients had expired and all the other small engine makers fitted their own version.

We used to fit the purple ones to racing Bantams and for $ 15 got an ignition that never missed and would run the engine up to 15,000, yet had enough retard to allow a Monza push start.

I am now saving money for the Atom Edger. That is one nice machine.
 

bertsmobile1

Lawn Royalty
Joined
Nov 29, 2014
Threads
64
Messages
24,647
Excellent explanation! That makes perfect sense.

I hate to mix apples and oranges but one reason I thought of this device was I was wondering if it may work on a car. However after you explained how the module works, I doubt that it would. You mentioned that if you connect it to 12 volts it will fry the module. So in a small engine, the coil is energized by an magnet in the flywheel, every time the flywheel passes the coil. Where as on a car, the coil is powered by battery voltage. Correct?

Are you familiar with wasted spark ignition systems?

My Trabant uses 2 sets of points and two ignition coils. One set for each cylinder.

6e22417756f8fabd6457dd83f2f75694.t00000175_b1.jpg


My Citroen 2CV also has a 2 cylinder engine (but a four stroker) and uses a wasted spark ignition system. I have an ignition coil from a Harley Davidson on my 2CV with two plug wire outputs.

I wondered if this type of system would work on a 2 stroke engine and after doing some research it has been used on other 2 cylinder 2 stroke engines.

I was not happy with the aftermarket electronic ignition systems on the market.

6573ba5aee9fcd8fa6a07a294c4dddfc.t00000722_b1.jpg


First of all, the points lobe is oblong instead of square like most points system so when the plastic ring slides over the points lobe "easily", the coils fires after top dead center so in order to get the timing closer to TDC, the ring has to be forced onto the lobe.

Also the circuitry is mounted on the board which means if you accidentally touch something with a screwdriver with the ignition switches on it will short something out. Well guess what, I shorted out one of the transistors doing just that. My mistake but the components are vulnerable.

Then there is cost. Shipping from Germany is quite expensive. A replacement unit would cost around US$ 170. That's including 30 Euros for shipping. You can buy a Hot Spark ignition system + free shipping just for what it costs in shipping from Germany.

So I decided to build a better mousetrap. I used a Hot Spark system for a VW Type 1 and I am firing both coils simultaneously.

Here is a video in the testing phase.

https://www.youtube.com/watch?v=LvllaO908p8

I'm in the process of refining the system. So this is not the final result.

One of the biggest challenges was trying to figure out where the transistor was located in the module in order to just get the engine started and running. I painted some reference marks above the magnets. Using a timing light shows the magnets are positioned at the leading and trailing edges of the module. Then through trial and error finally got it the ignition spot on.

My only concern is these Hot Spark systems are finicky. The instructions says anything above 13.7 volts will cause the module to overheat. So they recommend a ballast resistor to drop the voltage if this is the case. And also not to use low resistance ignition coils. So there has to be some tests conducted to make sure the module is compatible with the coils.

My concern is will firing two coils simultaneously cause the module to fail? I'm keeping the breaker points in the trunk and will be prepared to throw it back on in case the system fails.

The Petronix Ignitor does not seem to care. My suspicion is the Pertronix Ignitor has a built in regulator to avoid spikes. That may explain why a Petronix system sells for twice as much as the Hot Spark systems.

Any thoughts on this welcome!

Not familiar with any of the units you mentioned.
the triggers on all of these units also uses the Hall effect to determine how fast the magnets & thus the engine is turning and thus what advance ( lack of retard ) to apply to the spark.
The problems come with the switching transistor as that is carrying the load applied by the coils and thus is affected by the coil resistance.
The number of sparks makes little difference so long as the unit has sufficient cooling to dissipate the heat .The problem is the total load of each switch.
As such using a duel coil drops the load because the coil only draws the same 4 amps but produces 2 sparks.

Under voltage & over voltage are problems for the chip that determines how much advance to apply to that particular spark.
Most chips in common use go full advance when they are working in an under voltage situation because they use the supply voltage as the refference point.
Over voltage is easily capped by a resistor but of course that involves heat.
On motorcycles you get a better ignition by putting a conditioner in power feed to the controller.

Just about all of these unit have a preferred resistance for the coils so try to work you system to keep within the ohm range specified and you will be fine.
Be careful if you decide to use a motorcycle coil as a lot of them are AC and have finer windings so shoving 3A @ 12 volts down them will fry them in no time flat.
 
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