First time I have posted here.
I have been following since this thread since it first started on this forum.
I have built a circuit based off of the picture diagram at the beginning. I'm currently not using my 400w Black and Decker inverter because I can't get more than about 2 or 3 sparks and something trips internally and it shuts itself off. This happens with everything from a 1 microfarad to 150 microfarad capacitor. I gave up on the inverter for now and went to something I know is sure to work. I'm using 110v AC from a wall socket going through 4 60w and 2 75w light bulbs in parallel to give me 390w AC. Wish I could attach a picture but my wife has the digital camera right now. I run this into an 8 amp full wave bridge rectifier. The negative from the bridge goes to ground on the MSD coil, spark plug(motor) ground, and one side of a 135 microfarad capacitor. The positive side of the bridge connects to the spark plug via 16 1N5407 diodes. The output of the coil is connected to the spark plug also. It looks very much like the picture diagram at the front of this post except  where the SPDT switch is I have fabricated a set of points that are operated by a cam lobe collar locked down by a set screw on the output shaft of a Briggs & Stratton 5HP Horizontal shaft engine. So far I've tried timing settings from 40 degrees before top dead center to 60 degrees after top dead center. I haven't been able to get it to run with only water. I can tell you this though- there is no way a normal ignition system would take the amount of water I've run through this engine. It seems to want to try to run on water at low rpm with the throttle valve completely closed.

I have run out of time for now and will be gone for 4 days. Will try again when I get back.

I'd like to mention that there is a big difference I think between the picture diagram and the circuit diagram at the beginning of this post from my point of view. The picture diagram is firing a capacitor THROUGH the coil and the circuit diagram is firing a capacitor ON TOP OF a coil discharge. I think this leaves more to be investigated.

I'd also like to mention that while using this setup the spark plug will fire without being grounded to the circuit. The engine is mounted to wood boards for insulation purposes. I accidentally forget to connect the ground from the circuit to the engine block and the plug still fired. As soon as I touched the motor I got shocked and then figured out I forgot the ground wire. Any explanations on this?

If someone is going to try this be very careful. I don't touch the engine while starting or running it. I turn it over with a 1/3 HP electric motor via a drive belt pulley from a water pump off an old chevy. If you take off the recoil starter and remove the ratchet clutch a water pump pulley will bolt right on with a  fine thread nut. Water pump pulleys are about 6" in diameter. I put a 2" pulley on the electric motor. It turns over great! When the engine starts firing, unplug the electric motor or it pulls down the engine. This way I can turn it over while watching the resistor light bulbs and get an indication of when the plug has cleared itself and starts firing again after being drowned out.

I originally tried turning it over with a 3/4" electric drill but for some reason it caused a full draw on the resistor light bulbs. I guess it was searching for a ground through the drill.

Happy testing everyone!!!!!
God loves you
MIke

Quote from: Ricardoch on July 05, 2008, 04:15:43 PM
As the HV is used to give the bridge to the low current from the inverter... maybe could it be possible to run it direct from the battery??
If you connect the positive battery through a direct wire to the plug with a strong diode pack to avoid reverse from HV the battery will find the road open as soon as the HV sparks and a 12 volt battery can deliver enough power to melt the plug.

I thought the same thing a time ago and  first limiting current with one 12V lamp or more in parallel for more current, and if it works replace the lamps with a current limiting transistor.

Max .

I cannot get it to work on the lawnmower. I have the same problem with the test circuit. If I open the LV circuit anywhere then I can get my HV arc. If I don't open the LV circuit I cannot get a HV spark. With the test circuit I had to reverse polarity on the ignition coil to get this to work. I'm sure that's what my problem is on the lawnmower but there is no way to reverse the polarity with a magneto that I know of.

Another thing Ossie told me to check was the polarity of the coil. I did this test with ONLY the HV circuit hooked up. When the diodes are blocking flow from the coil to ground I get no fire, when they are blocking from ground to the coil I get fire. It is this way with the car coil and the lawnmower. Can somebody explain this to me because I thought electricty always flowed from neg to pos but according to that test it is flowing from the coil to ground which would be backwards.

Only thing I know to do is get a lawnmower with points ignition and bypass the magneto and use the points to trigger my car ignition coil so that way I can reverse the polarity on it so it will work. I've yet to have anybody really explain the flow of this circuit so until I understand it then I'm at the mercy of you people that know electricity.

I've tried the string of diodes in every place in the circuit I can think of backwards and forwards and nothing helps.

Quote from: bumfuzzled on July 05, 2008, 07:19:06 PM
I cannot get it to work on the lawnmower. I have the same problem with the test circuit. If I open the LV circuit anywhere then I can get my HV arc. If I don't open the LV circuit I cannot get a HV spark. With the test circuit I had to reverse polarity on the ignition coil to get this to work. I'm sure that's what my problem is on the lawnmower but there is no way to reverse the polarity with a magneto that I know of.

Another thing Ossie told me to check was the polarity of the coil. I did this test with ONLY the HV circuit hooked up. When the diodes are blocking flow from the coil to ground I get no fire, when they are blocking from ground to the coil I get fire. It is this way with the car coil and the lawnmower. Can somebody explain this to me because I thought electricty always flowed from neg to pos but according to that test it is flowing from the coil to ground which would be backwards.

Only thing I know to do is get a lawnmower with points ignition and bypass the magneto and use the points to trigger my car ignition coil so that way I can reverse the polarity on it so it will work. I've yet to have anybody really explain the flow of this circuit so until I understand it then I'm at the mercy of you people that know electricity.

I've tried the string of diodes in every place in the circuit I can think of backwards and forwards and nothing helps.

Hi bumfuzzled and all,

I did some bench tests with a new line trimmer motor yesterday using only water. The motor is a two stroke motor and has a fully enclosed electronic magneto coil. I also found that the pulse coming out of the magneto output was negative. So accordingly I connected the positive of my discharge circuit to the ground of the spark plug, but still I could not get the whole circuit to fire in the open as the ignition spark would not work. I found that I had to put a 12kV microwave oven diode in series with the ignition coil/magneto's output such that it was connected to and pointing to the magneto's output lead. This fixed the problem and now the circuit fires just fine in the open.

Because the HV pulse is essentialy the back emf from the ignition coil/magneto, there is a smaller pulse of the opposite polarity just preceding it which is the power pulse the coil needs to have to create a back emf, by not having the 12kV diode, it seems that the discharge circuit shorts out this preceding power pulse and that is why it needs a diode in series with the output of the ignition coil/magneto and still be able to create the required ignition spark.

The first thing I found was that the discharge circuit would not fire inside the cylinder. I could tell this by looking at my ammeter connected to the input of the inverter. capacitor70 used a household light bulb connected in series with the 240V section of his discharge circuit which also provides a very good indication if the discharge is occurring in the cylinder or not as there is no other way to know this, unless the motor runs. After a considerable amount of test and diagnostics, I found that for some reason, perhaps even because of the water vapour, that the ignition spark was too week to occur and allow the discharge circuit to fire inside the cylinder for the spark gap size I was using. Reducing the spark gap did resolve this problem to a point, as I found that it needed to be reduced so much as that now it is prone to getting clogged with water very easily. But also, a reduced gap does not appear to be benificial to the plasma water explosion as indicated by outside tests. Larger spark gaps appear to cause larger explosions.

All up after numerous trials I found that I was only able to get the motor to fire with water only once. By fire I mean one explosion pushing the piston down once in the correct direction and not running. I also found that a number of times I could feel the motor fire as a pressure in the reverse direction on the pull cord. This is indicative that the timing appears to be advanced from TDC so if this is the case, then there is no way for me to adjust the timing on this motor as it has a fixed magneto, without modification to the design and ignition system of the motor. To get the motor to fire just once on this motor it required me to use 310uf of capacitance in the discharge circuit. Firing this amount of charge out in the open with water sprayed on the spark plug sounds like a gunshot, I can tell you!

There is also quite alot of work to be done in regard to the air/waterfuel mixture required. But this can only be explored once the motor can be setup to fire regularly. So from my initial tests, I see more advantages in doing this on a larger 4 stroke motor with a stronger ignition system and variable control of the timing and air/waterfuel mixture.

Please see the following pictures of my setup.

Regards,

Ossie

Quote from: callanan on July 05, 2008, 08:27:07 PM
Hi bumfuzzled and all,

I did some bench tests with a new line trimmer motor yesterday using only water. The motor is a two stroke motor and has a fully enclosed electronic magneto coil. I also found that the pulse coming out of the magneto output was negative. So accordingly I connected the positive of my discharge circuit to the ground of the spark plug, but still I could not get the whole circuit to fire in the open as the ignition spark would not work. I found that I had to put a 12kV microwave oven diode in series with the ignition coil/magneto's output such that it was connected to and pointing to the magneto's output lead. This fixed the problem and now the circuit fires just fine in the open.

Because the HV pulse is essentialy the back emf from the ignition coil/magneto, there is a smaller pulse of the opposite polarity just preceding it which is the power pulse the coil needs to have to create a back emf, by not having the 12kV diode, it seems that the discharge circuit shorts out this preceding power pulse and that is why it needs a diode in series with the output of the ignition coil/magneto and still be able to create the required ignition spark.

The first thing I found was that the discharge circuit would not fire inside the cylinder. I could tell this by looking at my ammeter connected to the input of the inverter. capacitor70 used a household light bulb connected in series with the 240V section of his discharge circuit which also provides a very good indication if the discharge is occurring in the cylinder or not as there is no other way to know this, unless the motor runs. After a considerable amount of test and diagnostics, I found that for some reason, perhaps even because of the water vapour, that the ignition spark was too week to occur and allow the discharge circuit to fire inside the cylinder for the spark gap size I was using. Reducing the spark gap did resolve this problem to a point, as I found that it needed to be reduced so much as that now it is prone to getting clogged with water very easily. But also, a reduced gap does not appear to be benificial to the plasma water explosion as indicated by outside tests. Larger spark gaps appear to cause larger explosions.

All up after numerous trials I found that I was only able to get the motor to fire with water only once. By fire I mean one explosion pushing the piston down once in the correct direction and not running. I also found that a number of times I could feel the motor fire as a pressure in the reverse direction on the pull cord. This is indicative that the timing appears to be advanced from TDC so if this is the case, then there is no way for me to adjust the timing on this motor as it has a fixed magneto, without modification to the design and ignition system of the motor. To get the motor to fire just once on this motor it required me to use 310uf of capacitance in the discharge circuit. Firing this amount of charge out in the open with water sprayed on the spark plug sounds like a gunshot, I can tell you!

There is also quite alot of work to be done in regard to the air/waterfuel mixture required. But this can only be explored once the motor can be setup to fire regularly. So from my initial tests, I see more advantages in doing this on a larger 4 stroke motor with a stronger ignition system and variable control of the timing and air/waterfuel mixture.

Please see the following pictures of my setup.

Regards,

Ossie

That motor setup was NOT a failure, look what you learned!!!!!  Most impressive........I bet your next one WILL work....That 35 degrees AFTER TDC looks more and more like a viable setting.

Ben