Omega type W ignition Dual plugging...coils, ohms?

[mattcfish]

I'm dual plugging my bike with a crank mounted Omega (type W) ignition. http://www.omegaignitions.com/faq.html
I know a type V would allow me to go with much lower resistance, but I have what I have. For dual plugging Omega specifies using coils with a combined resistance of 1.8 to 5.0 ohms. My issue is, how do I get the lowest resistance coils without going below the 1.8ohm mark?
2x Dyna Blue .7ohm dual coils would =1.4 ohms. Close...but too low for specs given. Could damge the amplifier?

2x Dyna Brown 1.5 ohm dual coils =3 ohms...acceptable but more than I want.

Currently, I have 2x Dyna Grey 2.2ohm dual coils= 4.4 ohms... acceptable but getting to the outer limits and possible reducing spark.
Can coils be mixed and matched? Say a .7 ohm Blue coil and a 1.5 ohm Brown to =2.2 total ohms. Run the top plugs off one and the bottom off the other.
Any other configurations out there that might get me closer to 1.8?

[robtg]

Something to think about--Would "path of least resistance" apply with mismatched coil resistance? 3 ohm would be my choice. With the upper and lower limits given, it would seem somewhere in the middle would be ideal.

[Major Softie]

Something to think about--Would "path of least resistance" apply with mismatched coil resistance? 3 ohm would be my choice. With the upper and lower limits given, it would seem somewhere in the middle would be ideal.

I don't know if that could happen if mismatched coils were wired in parallel (don't think so, but not positive), but we're talking about sets wired in series, so that would not apply. In parallel, resistance is reduced by every additional parallel path, rather than the increased resistance seen in series.

That's one possible solution though. If you can find higher resistance twin tower coils designed for 12v, say 4 ohm, could you not run them in parallel and perhaps get closer to your goal?

[robtg]

Something to think about--Would "path of least resistance" apply with mismatched coil resistance? 3 ohm would be my choice. With the upper and lower limits given, it would seem somewhere in the middle would be ideal.

I don't know if that could happen if mismatched coils were wired in parallel (don't think so, but not positive), but we're talking about sets wired in series, so that would not apply. In parallel, resistance is reduced by every additional parallel path, rather than the increased resistance seen in series.

That's one possible solution though. If you can find higher resistance twin tower coils designed for 12v, say 4 ohm, could you not run them in parallel and perhaps get closer to your goal?

Further thinking leads me to ---mismatched in parallel not happening but series, maybe. I'm a shade tree engineer so i do a
lot of "try it and watch for smoke" when it involves ignition on my own projects.

[mattcfish]

Something to think about--Would "path of least resistance" apply with mismatched coil resistance? 3 ohm would be my choice. With the upper and lower limits given, it would seem somewhere in the middle would be ideal.

I don't know if that could happen if mismatched coils were wired in parallel (don't think so, but not positive), but we're talking about sets wired in series, so that would not apply. In parallel, resistance is reduced by every additional parallel path, rather than the increased resistance seen in series.

That's one possible solution though. If you can find higher resistance twin tower coils designed for 12v, say 4 ohm, could you not run them in parallel and perhaps get closer to your goal?

Further thinking leads me to ---mismatched in parallel not happening but series, maybe. I'm a shade tree engineer so i do a
lot of "try it and watch for smoke" when it involves ignition on my own projects.

Thanks for discussing this. I had to do some research to get what you guys were talking about. http://en.wikipedia.org/wiki/Series_and ... l_circuits

Can you explain the idea of resistance going down on a parallel circuit and how you calculate it given the resistance values of two dual coils?

Omega is against wiring in series, although I'm not really sure what they are talking about.

Dual Plugging

We are advising strongly against using two dual coils in series on one output! The two coils are generating twice the back-EMF of one coil at firing time that the amplifier must withstand. That phenomena is also related to the primary impedance of the coil and total magnetic charge.
However (not supported and thus voiding the warranty):
Since magnetic charge is a function of ampere-turns (inductance), the current level is an adjustable parameter that can be utilized to achieve a high energy system while still maintaining a low level of back EMF toward the amplifier. If a low impedance primary winding is used with high current capability, it is conceivable to apply two coils safely for dual plug use on one amplifier.

It's still Greek (or German) to me. What do you guys make of it?

[StephenB]

Dual Plugging

We are advising strongly against using two dual coils in series on one output! The two coils are generating twice the back-EMF of one coil at firing time that the amplifier must withstand. That phenomena is also related to the primary impedance of the coil and total magnetic charge.
However (not supported and thus voiding the warranty):
Since magnetic charge is a function of ampere-turns (inductance), the current level is an adjustable parameter that can be utilized to achieve a high energy system while still maintaining a low level of back EMF toward the amplifier. If a low impedance primary winding is used with high current capability, it is conceivable to apply two coils safely for dual plug use on one amplifier.

It's still Greek (or German) to me. What do you guys make of it?

Matt,

It means: don't do it, it can fry your amplifier. I can add more gibberish: the "Ohms" is only one part of the equation, there are also "Henry's" and "Farrad's" that add to it. The Back EMF that the author above was talking about is a function of all three, Ohm Resistance, Inductance and Capacitance. When the coil is fired it creates an Electro-Magnetic Force (EMF) that induce a voltage back on the primary side (hence Back EMF) through to your amplifier. That is the danger with too many coils in series. It's like the kickback of a rifle.

My recommendation: first off, you need two 6V coils with dual output. Take 1.5Ohm for each dual coil and pray. It may work, it may fry the amplifier ... you need an electronics lab to do some experiments to retire risk.

Just for the sake of it:
Performance limits of the OMEGA W: 12V and 1.8Ohm primary resistance or higher (I wouldn't go as low as 1.8Ohm in such a risky application, think 3Ohm ... but even then!)
Two 6V coils connected in series: R1 + R2, each coil requires 6V supply, so you need to apply 12V (may work if R1+R2 larger than 3Ohm)
Two equal 12V coils connected in parallel: 1/2 R (may work if R larger than 3Ohm but Back EMF might kill the amplifier before you know it)
Don't mix and match, "path of least resistance" applies it can create all sorts of performance issues.

Your money, your risk. I wouldn't try it (and I know what I am doing around Electronic Ignitions) unless you're a guy that used a Hammer to fix a glass frame: get the right tool for the job.

[Roy Gavin]

Makes me glad I bought a Boyer Micropower, as the kit includes two dual output coils, 0.7 ohm resistance, wired in series.
Couldn't see the voltage marked on the coils anywhere

Costs less than the Omega does without coils, and has a better dual plug curve too.

[Major Softie]

Can you explain the idea of resistance going down on a parallel circuit and how you calculate it given the resistance values of two dual coils?

Well, the math is explained pretty clearly on the wiki site you mention. As far as explaining the idea, think of water pressure being forced through a hose with a little orifice (resistance) placed in it. If the hose branches into multiple branches, and each branch has one of those little orifices in the hose (sort of like a jet in a carb), then the more branches, the more orifices, the easier it is to flow water through the whole thing. If you had enough branches, the size of the jets would all add up to the size of your original hose, and the whole thing would have no more resistance to flow than the single hose itself (theoretically). That's how resistors behave in a parallel circuit.

If you put all those jets inline in one hose, the more of them you put in, the harder it is to push water through the hose (I don't know fluid dynamics, so I'm not sure how accurate this part is with water, but it demonstrates what happens with electrical resistors in series ).

[Garnet]

Next time I'm havin trouble with my ignition i'm gettin out the garden hose.

What could go wrong?

[mattcfish]

Dual Plugging

Matt,

It means: don't do it, it can fry your amplifier. I can add more gibberish: the "Ohms" is only one part of the equation, there are also "Henry's" and "Farrad's" that add to it. The Back EMF that the author above was talking about is a function of all three, Ohm Resistance, Inductance and Capacitance. When the coil is fired it creates an Electro-Magnetic Force (EMF) that induce a voltage back on the primary side (hence Back EMF) through to your amplifier. That is the danger with too many coils in series. It's like the kickback of a rifle.

My recommendation: first off, you need two 6V coils with dual output. Take 1.5Ohm for each dual coil and pray. It may work, it may fry the amplifier ... you need an electronics lab to do some experiments to retire risk.

Just for the sake of it:
Performance limits of the OMEGA W: 12V and 1.8Ohm primary resistance or higher (I wouldn't go as low as 1.8Ohm in such a risky application, think 3Ohm ... but even then!)
Two 6V coils connected in series: R1 + R2, each coil requires 6V supply, so you need to apply 12V (may work if R1+R2 larger than 3Ohm)
Two equal 12V coils connected in parallel: 1/2 R (may work if R larger than 3Ohm but Back EMF might kill the amplifier before you know it)
Don't mix and match, "path of least resistance" applies it can create all sorts of performance issues.

Your money, your risk. I wouldn't try it (and I know what I am doing around Electronic Ignitions) unless you're a guy that used a Hammer to fix a glass frame: get the right tool for the job.

Stephen, All the talk about water flow and path of least resistance has simplified this for me. One coil with low resistance and one with high resistance wired in would not work because the flow would be to the coil with least resistance.