lawn mower magneto conversion ,,, ideas

[new2guru]

Gday,

intro.

cars with old style distributors are easy too convert too plasma sparks, -they require no delicate solid state components too damage,

however a magneto \ magnet on the flywheel - super vintage style - poses its own set of problems, - the goal is too find solutions using readily available parts that will last.

the reason for the goal of using plasma instead of magneto spark ..; is too enable the engine too more happily run on petrol vapors and other less explosive\cumbersome alternative fuels

the issues are....

..........choosing a switching mechanism... eg relay \ transistor \ valve \ theristor...

.........a method of converting the spark from the magneto into a form suitable of triggering the switching mechanism

the switching device will be powering a CDI system - capacitive disscharge ignition, which involves dumping a cap into a car coil for each pulse...

the intense plasma spark can be produced by using the spark gap (or more specifically the CDI spark) too complete a circuit and conduct a high voltage dc (200+v), utilizing a diode or 3 tp prevent the cdi spark from going along the DC wire instead of the spark gap \plug

this project has been largely completed already by others, but one area not adequately addressed is the triggering \ switching issues. ....reed switchs, secondary coils..... many avenues.... lets find a good one !

 

[new2guru]

just too get the ball rolling,

ive tried using a reed switch inplace of the magneto, too trigger a relay which pulses the ignition coil \ plasma setup.... this worked better than you would imagine... the engine fired one out of 4 cycles give or take.... but actually ran... surprising because the magnet is quite long thus not giving a clear signal too the reed\relay

the reed switch was then moved tooo the opposite side of the flywheel were a small focused magnet could be positioned - this worked much better, but showed up the inherent weakness of using relays, not just the longevity but the rpm limitation due to slow switching...better relays are avaliable for sure...this one is out of a tv and quite old...

voltage transients seem to immediately destroy any transistor and even IRGP i replaced the relay with, even with rudimentary snubbers

last night it occurred that i could wind a coil and use the magneto spark to create emf and trigger the reed switch.... sounds ok too me but im not having any luck with the coils, wound 4 so far with carbon nail core, high tensile bolt core, aluminum... no luck.. i only have tiny ferrite that are round...

anybody have a googlerod core i can try ?

 

[BrownOut]

You should be able to get transistors to work in place of the realys. First is to ascertain the cause of their failure. Most likely, it's high voltage kickback from the coil. Liberal use of protective devices, such as transorbs, should do the trick. After all, modern cars are all made with transistor switches for ingition purposes. I recommend a high voltage MOSFET for the switch.

 

[tcmtech]

I am not sure about what you are referring to as "plasma sparks" or much of anything else for that matter.

Got any schematics or pictures so we have a more accurate understanding of what it is you are attempting to do?

 

[SABorn]

Personally i think the magneto systems on lawnmowers are a good system, and the newer electronic ingition systems are problematic.
Electronic ingition systems use a different flywheel and smaller magnets.

Why do you want to complicate a very simple reliable ingition source, is what i dont understand.

The CDI systems i have repaired or built have all used a scr as a trigger device.

Instead of your reed switch (which is very poor idea) you could use a coil from a relay to generate a ac signal

The use of a relay is also a poor idea and would go through a 100,000 closeures by the time you mowed 1 lawn.

 

[new2guru]

SABorn ; agreed relays are not a longterm solution, just a convenient test device... transistors are probably were its heading, however im still looking for an analouge solution... coils only would be great as it would probably provide the same reliability of the original setup...

i will make a simple diagram tomorrow, 5am atm...

this is what the triggering circuit has too cope with

YouTube - Water Sparkplug | Plasma Ignition| Booster Caps

mmm blinding plasma

 

[shortbus=]

Here is a link to a points eliminator circuit that works; Ign Module /Rev engineering - Page 2 - All About Circuits Forum

 

[tcmtech]

Apparently you have to become a member to see the links?

 

[KeepItSimpleStupid]

Magnetic reluctance, optical, hall effect.

Per Tecumseh's manuals, the timing has to be altered when converting a points system to the electronic system without the battery. The insert changes the position of the key slightly.

I did an optical conversion on a car Dwell was based on the length of the slot.

 

[new2guru]

sHORTBUS : Thnx for the link, i should have mentioned earlier the motor i have too test with is only a single cylinder - no points , does make it more difficult, less options without a "plugs & points" arrangement... however there is alot of these 4stroke mowers around so its undoubtedly worth a solution

i try to practice kiss when dealing with electronics ... however there is still 20 simple ways of doing something which is why i forgot about the optical option !!.. i will be getting some IR receiver \ LED to replace, its a step up from mechanical components and il try anything twice,

 

[new2guru]

Prescript;

this is not my work, from the guys at energetic

 

[shortbus=]

sHORTBUS : Thnx for the link, i should have mentioned earlier the motor i have too test with is only a single cylinder - no points , does make it more difficult, less options without a "plugs & points" arrangement... however there is alot of these 4stroke mowers around so its undoubtedly worth a solution

Thats what I was saying, it eliminates the need for points and is for single cylinder engines. It uses just the original magneto coil and the circuit to run. You really should check out the post/circuit.

 

[tcmtech]

Looking at the schematic would suggest I would need to drag an extension cord around to power the ignition system for my gas powered lawn mower that was cordless to start with.

I designed a simple fly-back coil based ignition system about 20 years ago, I called it Hyper arc, that was far simpler and produced a very hot HF "plasma spark" with a dwell time only limited by how long the points where open and was capable of being powered off of a common 6 - 12 volt battery or the small flywheel alternators that fit small engines.

 

[MikeMl]

A spark is a spark is a spark. In the context of a spark plug, what the h... is a plasma?

 

[tcmtech]

The whole concept, as I see it from what he has posted, seems like reinventing the wheel by making it more rectangular and replacing the rubber with concrete.

The whole concept comes across as a cumbersome, inefficient, and unreliable solution to problem that doesn't exist.

 

[SABorn]

The whole concept, as I see it from what he has posted, seems like reinventing the wheel by making it more rectangular and replacing the rubber with concrete.

The whole concept comes across as a cumbersome, inefficient, and unreliable solution to problem that doesn't exist.

Here,here, i could not agree more!

 

[new2guru]

The whole concept, as I see it from what he has posted, seems like reinventing the wheel by making it more rectangular and replacing the rubber with concrete.

The whole concept comes across as a cumbersome, inefficient, and unreliable solution to problem that doesn't exist.

haha humbling indeed because i immediately realise the truth in this, my goal however is not too create an electric lawnmower using a petrol engine instead of an induction motor, ... i would like too see these garden variety engines being used as portable generators.

i like to think of it as reinventing an electric car using circuits from all manor of different technology... cumbersome analogy perhaps but the 3.5\10 hp genny would be spinning up automotive alternators, making the 240v source easy too achieve with a few tappings on the stator running into a CW multiplier

the plasma sparks that can be achieved with this circuit are so powerful you can blow the hell out of your spark plugs, (thats another problem), but when ignited in a compressed cylinder, the plasma explosion is intense enough to fire an engine on the smallest amount of fuel vapor, and indeed a wire variety of fuels

SHORTBUS ; did i miss something in the previous link ? reviewing the schematics carefully i did not notice a solution, - looknig again with fresh eyes,

 

[MikeMl]

...
the plasma sparks that can be achieved with this circuit are so powerful you can blow the hell out of your spark plugs, (thats another problem), but when ignited in a compressed cylinder, the plasma explosion is intense enough to fire an engine on the smallest amount of fuel vapor, and indeed a wire variety of fuels

Oh, Oh, more overunity stuff!

 

[tcmtech]

You blow the hell out of your spark plugs because you are striking an arc from a line level power source with no current limiting in place. Spark plugs are designed to fire at tens of ma not tens of amps.

Those garden variety engines are used on generators all the time and have been since they where first created in their present layouts some 60+ years ago. The design has not changed much since. A 5 HP 2010 B&S still likes about like a 1950's B&S but with more plastic.

 

[new2guru]

the only solution i can see on that webpage was designed for a points setup and relys on using presumably a low voltage from the points to trigger a transistor \ IGN coil , this i would have trouble doing with a 3kv +\- transient from the magneto, largley because there is no stable voltage.... at 1000rpm you can block enough of the power too trigger a transistor without destroying it, but at 2000rpm the spark is of a different intensity requiring the resistance too altered as the rpm changes, - in my eyes that makes a crude setup that requires unnecessarily complicated engineering---

at this stage it would be ok too trigger the IGN coil with IRled \ reed sw, but striking gold would be too have a method of triggering that can utilize the existing magneto spark thus forever simplifying the timing and installation

this is a winning project - if its as simple as reinventing the wheel, or even the shuttle discovery, it would be well worth it,