Diode Formula (Equation)

Thread Starter

Livingwaters

Joined Mar 4, 2008
16
Something doesn't really add up with the 34KV@0.83A.. I can only see this happening momentarily for a very short time through a condenser/capacitor. 28KW isn't exactly small potatoes!!! Especially since most batteries can supply about 600A momentarily(most go to starter motor) at 14.4V, which is 8.64KW... I found it odd that rectifiers were picked for this specification as if it were continuous. You can easily get away with much less if it is for a surge, which it must be.

Steve
Steve and Ron,

Thanks for the input. Let me try to get the old gray matter stirring.

The 34Kv @ 0.83 amps is happening at intervals. As the rotor in the distributor revolves and passes the arc points on the distributor cap the circuit is completed. The ignition points hooked also to a condenser (capacitor) breaks the circuit. This allows the circuit to complete through the primary winding of the ignition coil (there are 2 windings in the coil, one positive, and a secondary negative through the points) Hope this makes sense. The secondary voltage collapses when the points close.....allowing the full 34Kv built up in the coil to run to the spark plug. The gap at the sprk plug electrodes grounds the current for an instant. Ignition of the fuel vapors, an explosion, voila, power. The coil then recharges for the next cycle.

In this arrangement, rectifiers are used to keep the voltage from running back to the inverter. If you remember, we are running 110V @ 20 amps 60 cycles (this may have to be reduced some) from a dc to ac inverter to supply a charged state at the spark plug electrodes. This is our modification. Since the current is flowing only during burn time, do you think the diodes are needed?? Is there another way of protecting the inverter from feedback current??


These experiments are aimed at developing more eco. friendly fuels which are renewable, affordable, and non polluting to the environment.


Thanks for the help,
Livingwaters
 

Ron H

Joined Apr 14, 2005
7,014
My point is, 34kV and 0.83A do not occur ar the same time. And you mentioned that the spark "grounds the current for an instant". Are you running your spark plug in a combustion chamber, or other pressurized environment? Under pressure, the voltage required to sustain the arc will be higher that at atmospheric, and the current will be reduced.
 

Thread Starter

Livingwaters

Joined Mar 4, 2008
16
Ron, You are much better versed at this than I.

Yes, this is happening within a combustion chamber in an internal combustion engine.

So, how would it be determined what diodes to use in the protection circuit? Since the current isn't flowing all the time, except for the 110, do you think that lower voltage diodes would work in this circuit?

Thanks for your help,
Livingwaters
 

Ron H

Joined Apr 14, 2005
7,014
Ron, You are much better versed at this than I.

Yes, this is happening within a combustion chamber in an internal combustion engine.

So, how would it be determined what diodes to use in the protection circuit? Since the current isn't flowing all the time, except for the 110, do you think that lower voltage diodes would work in this circuit?

Thanks for your help,
Livingwaters
I see what look to me like several other problems:
1. The voltage across the spark plug during the burn time is 1-3kV, as I mentioned before.
2. I doubt you can force higher current without causing the voltage to increase above that value. This may cause the plug elements to overheat from the added power being dissipated.
3. If you try to use AC, I think the arc will extinguish before the first zero crossing of the current waveform, and will not reignite spontaneously. Of course, a half cycle of 60Hz (I think that was the frequency you mentioned) is about 8mS, which is longer than the normal burn time, but you would have to synchronize it with the points (or whatever switch you have). You might as well use a second coil instead.
 

thingmaker3

Joined May 16, 2005
5,084
I don't know a lot about automotive mysteries either, but isn't the spark duration from a common distributor less than 2 mS? If the inverter used is a standard 60 Hz model, how would one get the timing right between the distributor and the inverter pulses?

Also... if the goal is to supply lots of current through the arc once it has been established, wouldn't it be easier to use High-frequency HV to break down the gap & DC for the current rush? I've seen easy-start arc welders work this way. A capacitor keeps the DC current out of the HF/HV circuit and a choke coil protects the DC circuit.
 

Ron H

Joined Apr 14, 2005
7,014
I don't know a lot about automotive mysteries either, but isn't the spark duration from a common distributor less than 2 mS?
Yes.
If the inverter used is a standard 60 Hz model, how would one get the timing right between the distributor and the inverter pulses?
That was my point also.
Also... if the goal is to supply lots of current through the arc once it has been established, wouldn't it be easier to use High-frequency HV to break down the gap & DC for the current rush? I've seen easy-start arc welders work this way. A capacitor keeps the DC current out of the HF/HV circuit and a choke coil protects the DC circuit.
 

Thread Starter

Livingwaters

Joined Mar 4, 2008
16
Ron, and Thingmaker,

The goal is to keep a constant 110v @ 20amps "field" at the spark plug electrodes, which, theoretically collapses only when the full coil voltage.....24,000 volts @ 6.3 amps moves through to the plug electrodes causing the arc.

Previous tests show that the 110 will not arc across the plug electrodes....but create a magnetic field needed for proper polarization of the fuel/air mixture.

Timing is not needed for the110, since its purpose is to create a magnetic field within the combustion chamber. The cars ignition timing takes care of the final phase--- the combustion/reaction

I am trying to establish protection, using diodes, between the 110 circuit and the 34Kv initially coming from the coil. What voltage ratings on the diodes would be needed based on the Volts/Amps??

A little tedious at best..

Thanks for your help!
Livingwaters
 

Ron H

Joined Apr 14, 2005
7,014
Ron, and Thingmaker,

The goal is to keep a constant 110v @ 20amps "field" at the spark plug electrodes, which, theoretically collapses only when the full coil voltage.....24,000 volts @ 6.3 amps moves through to the plug electrodes causing the arc.

Previous tests show that the 110 will not arc across the plug electrodes....but create a magnetic field needed for proper polarization of the fuel/air mixture.

Timing is not needed for the110, since its purpose is to create a magnetic field within the combustion chamber. The cars ignition timing takes care of the final phase--- the combustion/reaction

I am trying to establish protection, using diodes, between the 110 circuit and the 34Kv initially coming from the coil. What voltage ratings on the diodes would be needed based on the Volts/Amps??

A little tedious at best..

Thanks for your help!
Livingwaters
OK, we know that you are trying to find some suitable diodes.

I am just trying to understand how they will be used. I maintain there is no way you can cause current to flow from your 110V source, through the plug, during the spark phase, or any other time, be it AC or DC. Without current, there can be no magnetic field.
 

Thread Starter

Livingwaters

Joined Mar 4, 2008
16
Ron,

There will be current flowing through the circuit, (Inverter 110 DC to AC 20 amps.) The goal is to protect the inverter from back feeding when the 24,000 volts moves on through. Likewise the circuit from the distributor needs to be protected from the 110 v @ 20 amps. also.

Any help in determining the diode strength needed to protect these circuits is greatly appreciated.

Thanks in Advance,
Livingwaters
 

Ron H

Joined Apr 14, 2005
7,014
Ron,

There will be current flowing through the circuit, (Inverter 110 DC to AC 20 amps.) The goal is to protect the inverter from back feeding when the 24,000 volts moves on through. Likewise the circuit from the distributor needs to be protected from the 110 v @ 20 amps. also.

Any help in determining the diode strength needed to protect these circuits is greatly appreciated.

Thanks in Advance,
Livingwaters
I don't know enough about high voltage diodes to recommend one, but I know enough about electronics and spark plugs to be pretty damned certain that the impedance of the spark is more than (110V/20A) 5.5 ohms. If it were, we wouldn't see scope photos like the one I posted where the voltage during the burn time is more than 1kV. What evidence do you have that you can force 20A through the spark wih 110V?
You may consider this an insult, but do you know Ohm's law?
 

thingmaker3

Joined May 16, 2005
5,084
If you want a magnetic field, you need to pass the current through a conductor. Be aware also that the field will establish and collapse 120 times per second, unless your inverter output is rectified and filtered to DC.

As Ron has noted, you won't get a magnetic field if the plug is part of the inverter loop. If you set up a coil or such for your magnetic field, you won't need diodes. You'll have isolation by virtue of the circuits not being connected at all.
 

Thread Starter

Livingwaters

Joined Mar 4, 2008
16
Ron, and Thingmaker,

Ron, no insult taken. Yes I'm aware of ohm's law. The frustrating problem is working with another's model. Previous work in this area dictates the use of the inverter, along with the stock ignition system. Some details are sketchy.

So, let me see if I am understanding this correctly. Even though there is theoretically 24kv going through the spark plug leads......only around 1-4 kv actually jumps the spark plug gap?? This would mean that diodes would not need to be above 24kv, but at a more realistic 6-8kv correct??

Thingmaker, regarding the coil. How would you be able to set this coil up to obtain a magnetic field at the plug?? And, not need diodes for protection...even though both circuits are running through the spark plug??

I believe that the previous work done in this area.....with the inverter.....may have been to establish a static electrical charge within the combustion chamber up to the point of the 24Kv jumping the gap on the spark plug electrodes.


Thanks for your help in this area! This field of research is much needed.

Livingwaters
 

nomurphy

Joined Aug 8, 2005
567
If I recall correctly, the spark plug fires just before TDC which is when the air/fuel mixture has been compressed to a fairly high pressure. Due to this highly pressurized mixture, the spark must be in the 30kV range in order to jump the gap and begin the ionization process -- which causes the mixture to explode. I believe it would take less voltage to jump the same gap at standard pressure. However, not all of the fuel is necessarily burned or contributes to the explosion, and some unspent fuel can be evacuated when the exhaust valve begins to open (this is why you see flames coming out of the exhaust on funny cars, they are not efficient during idle and lots of fuel is wasted). Unspent or poorly mixed fuel can also dampen the spark and the burn ("wetting out" within the combustion chamber).

One of the issues of fuel efficiency is the time it takes the mixture to burn -- the burn wavefront within the cylinder. By employing a higher voltage spark, or "hotter" spark, the fuel mixture will burn faster/better to some extent. Another tried method, has been to apply a "multi-spark" where many rapid sparks are used to keep the fuel burning.

The only use of the 110V, that I can think of off-hand, is to somehow provide an electrical potential or "pre-charge" to the plug. This may cause a "fat" or wider spark area to occur, causing a faster/better burn wavefront; and possibly a longer duration spark, where the ionization begins at lower spark voltages, boosted by the 110V, and therefore the "active" spark is there longer?
 

thingmaker3

Joined May 16, 2005
5,084
I didn't type "coil." I typed "coil or such." To reiterate: A magnetic field will only be established by a current. 110v is not enough to push a current across a gap.

What I don't understand is why the 110V from the inverter needs to be across the plug gap. It won't establish any magnetic field there. Even when the HV breaks down the gap, (and assuming the 110V peak occurs at the same time as the HV surge) the magnetic field will rotate around the arc. This would be no different than the HV by itself.
 

Thread Starter

Livingwaters

Joined Mar 4, 2008
16
Thingmaker, I understand the basic laws of electricity, however, I do have more questions. What is happening at the spark plug electrodes before arc occurs?? Nothing? There must be a magnetic field happening at some point before the arc occurs. I'm not clear on this. Seems to me that magnetic attraction causes the arc to occur once the voltage gets high enough to jump the gap. Please correct me, or explain this better.

Another issue is whether or not the 110 volt @ 20 amps can "piggy back" along with the 24Kv @ 0.83 amps and move on through to the spark plug?? Remember, the model used 110 volt @ 20 amps 60 cycles AC, while the 24Kv @ 0.83 amps is DC.

Hopefully, we can get to the bottom of this, and get this set up the correct way before testing anything.

Thanks for your help!

Livingwaters
 

beenthere

Joined Apr 20, 2004
15,819
The Wikipedia article on arcs does not support the preexistence of a magnetic field for arc formation - http://en.wikipedia.org/wiki/Electric_arc. The potential difference is the factor that ionizes the normally insulating medium and lets the current flow between the discharge points.

The reference for magnetic fields in arcs is for blowouts, where a coil makes a magnetic field to force the arc into a longer path so it will be extinguished.

Low voltage AC arcs tend to self-extinguish when the voltage goes to zero. It would be very interesting to see how you plan to introduce the AC voltage to the spark plug. The usual lead to the plug is resistive so it minimizes RF radiation. Such a lead would only conduct a few milliamps with 120 VAC as the propelling voltage.

Modern ignition systems in cars have higher voltages going to the plugs. I used to set the gap to .035". Now the gap has increased to something like .044, meaning that the spark will be more energetic.

Have you tried an experimental setup to introduce a magnetic field in the spark plug gap? A strong magnet with close poles would certainly be able to demonstrate the influence of a magnetic field on the spark. It could be quite interesting if a temporary field might be able to hold off the arc until a significantly higher voltage than normal had built up.
 

thingmaker3

Joined May 16, 2005
5,084
Thingmaker, I understand the basic laws of electricity, however, I do have more questions. What is happening at the spark plug electrodes before arc occurs?? Nothing? There must be a magnetic field happening at some point before the arc occurs. I'm not clear on this. Seems to me that magnetic attraction causes the arc to occur once the voltage gets high enough to jump the gap. Please correct me, or explain this better.
There is an electric field, not a magnetic field. The gap is a capacitor. The HV breaks down the dielectric of said capacitor. Only when the arc has been established does current flow throuh the plasma. (Plasma is a conductor. Fuel-rich air is a dielectric.)


Another issue is whether or not the 110 volt @ 20 amps can "piggy back" along with the 24Kv @ 0.83 amps and move on through to the spark plug?? Remember, the model used 110 volt @ 20 amps 60 cycles AC, while the 24Kv @ 0.83 amps is DC.
Refer to multiple references on timing earlier in this thread. Also, refer to Ohm's Law. Circuit current will never exceed E/R, no matter how many amps your supply can source. Your local power company can source an obscene quatity of Amps. Do they all flow through your computer? Or does your computer comply with Ohm's Law?
 
Beenthere,

I know this thread is a year old now, so this may be redundant. This attachment should clear things up a bit. They (waterfuel1978 yahoo group) where trying to figure out how to dump high current low voltage across a spark gap using the stock high voltage coil to initiate the the path. The attached circuit tells me that "they" finally ditched the ac idea as they are now using a bridge rectifier. Also using an isolating transformer to protect the inverter. This is the circuit being used to experiment with running an engine on water (not HHO). I've posted a couple of youtube links of engines supposedly running on water alone. They are pretty convincing, but that being said, I'd have to inspect an engine and see it run with my own eyes before i'd be convinced. On a separate note. I'm a club racer, love building and driving fast cars. I'd like to try this ignition setup on my track car and and see how it compares to an MSD or similar ignition box. I'd like to here you thoughts on that.

http://www.youtube.com/watch?v=tb3d_hf7R10
http://www.youtube.com/watch?v=pBCl3OdM9Y4
http://www.youtube.com/watch?v=nnUv6M0N6z4
 

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