AC driven ignition coil

J_Nichols · Nov 6, 2011

em2006,I really appreciate your solution but, Can you explain us a little bit what this circuit does?
I've very basic knowledge in electronics and I don't fully understand the circuit. I use 220V, but if you explain the more easy (110) there won't supose a problem to understand the other. thanks.

debe · Nov 6, 2011

J_Nichols said:
The ignition coil is for use in a remote controlled combustion motor.
The idea comes from this hyphotesis. The ignition coil helps to produce a spark to ignite the gasoline mix in the motor and it causes the explosion. For the ignition coil to work, it only needs to produce a magnetic field and when we disconnect the power source from the coil, a spark is created. If only magnetizing energy is necessary to produce the spark (reactive power), then the power factor will be zero because all the energy is reactive.

When we use DC, energy is consumed. But when using AC and only 100% reactive power (power factor = 0) then no wattage is used since Voltage x Intensity x Power Factor (0) = 0 Watts. But the coil can produce a magnetic field that doesn't produces work, and the energy of the spark cannot produce work. So watts = 0 and we can save energy from the ignition system of the rc car. Of course, I would need a transformer to produce AC and in the process (from DC to AC) I can loose some watts due to heat in the transformer and the miliwatts that the pulsing circuit uses, but forget the energy consumed in this last part.
Correct me.

This whole concept apears flawed to me. Its like you are trying to run an ignition system that draws no wattage. No Watts = No usable spark. In an internal combustion petrol engine when there is compression, it takes a higher voltage for the spark to jump the plug gap, compared to atmospherec pressure. Most 12v ignition systems draw several amps. The other option is a Magneto type ignition system.

J_Nichols · Nov 6, 2011

Magneto type ignition system

What kind of ignition system is that one? I've read that the magneto ignition system was one of the first that were used.
He used one coil and one magnet. But I don't fully understand how it works.

Reloadron · Nov 6, 2011

Think about all the small gasoline or petro engines on tools like lawnmowers, chainsaws and the like where there is no battery. A magneto is just a coil of wire wound on a core. When a magnet quickly passes the core a voltage is induced in the coil. In the case of a magneto the voltage is of sufficient amplitude to jump a spark across the gap of the spark plug. Give this a read.

Ron

J_Nichols · Feb 13, 2012

DerStrom8 said:
I don't know, I wouldn't trust connecting it directly to an AC source. I would use the lamp dimmer, like Ron suggested.

**broken link removed**

I've actually used that circuit a lot, and it works great. I bought a lamp dimmer for $4 at Walmart and pulled a capacitor off of an old circuit board. Just make sure that the cap isn't polarized, or it could explode. The voltage rating of the cap also needs to be well above the mains voltage (at least twice as much). With this circuit, you can run it directly off 120/240vac mains current and you get very nice arcs out of it.

But I must stress, as with all high-voltage projects, that you MUST be extremely cautious and careful when fooling around with this. Even if the output of the coil isn't enough to kill you, a high voltage arc through you to the mains power cord will create a low-resistance circuit to your household current. This IS enough to kill. Please take all necessary precautions to keep you and others safe.

Best regards,
Der Strom

something has gone wrong.
I tried the config you suggested using a 630 Volts 0.1 uF (that's the one I have at home) and I didn't noticed any spark in the output of the ignition coil. Then to prevent unscrew the part where the cap is joined with the dimmer (in this trying I want to light a bulb to test if the dimmer was working), I connected the wire to the exit of the dimmer while the cap was still connected to it (I only used one end of the cap while the other end of the cap was not connected to anything). It produced a small explosion in the dimmer, and it needed to switch on the fuses of my house (they where off after the experiment).
Now I try to light the bulb without any capacitor in the circuit and the dimmer produces an explosion. This time the fuses of the home don't get off.
do I've broke the dimmer?
Now, I try to connect

DerStrom8 · Feb 13, 2012

J_Nichols said:
something has gone wrong.
I tried the config you suggested using a 630 Volts 0.1 uF (that's the one I have at home) and I didn't noticed any spark in the output of the ignition coil. Then to prevent unscrew the part where the cap is joined with the dimmer (in this trying I want to light a bulb to test if the dimmer was working), I connected the wire to the exit of the dimmer while the cap was still connected to it (I only used one end of the cap while the other end of the cap was not connected to anything). It produced a small explosion in the dimmer, and it needed to switch on the fuses of my house (they where off after the experiment).
Now I try to light the bulb without any capacitor in the circuit and the dimmer produces an explosion. This time the fuses of the home don't get off.
do I've broke the dimmer?
Now, I try to connect

That does not sound very good. First, it's important to know that when running an ignition coil with the circuit I showed you, the dimmer needs to be almost all the way down in order to send a square wave to the coil. You must not turn it all the way up, or else you'll get a sine wave on the coil inputs, which won't give you anything (not to mention, deliver a rather high voltage to the coil).

Anyway, an "explosion" in the dimmer is probably a bad sign. It sounds to me like you should probably buy a new one--it should not "explode", as you said it does.

Regards

DerStrom8 · Feb 13, 2012

Duplicate post.

J_Nichols · Feb 13, 2012

DerStrom8 said:
That does not sound very good. First, it's important to know that when running an ignition coil with the circuit I showed you, the dimmer needs to be almost all the way down in order to send a square wave to the coil. You must not turn it all the way up, or else you'll get a sine wave on the coil inputs, which won't give you anything (not to mention, deliver a rather high voltage to the coil).

Anyway, an "explosion" in the dimmer is probably a bad sign. It sounds to me like you should probably buy a new one--it should not "explode", as you said it does.

Regards

I started with the lowest value in the dimmer and I increased it to.... around 20% of the total value. Nothing happened in the output of the coil.
I used the dimmer before this test (to light bulbs) and it worked well.
I think I've damaged something when I used only 1 end of the capacitor.

Well the question is If I can use a step down transformer to down 220 VAC to 12 VAC 3 amps, and switch off the ac source when the voltage is at its maximum. I can build a magnetic field using AC and then, when I switch off the voltage it would create an output in the ignition coil. This idea is right?
I would build a special circuit for switching off the AC power when the voltage is at its maximum.

DerStrom8 · Feb 13, 2012

J_Nichols said:
Well the question is If I can use a step down transformer to down 220 VAC to 12 VAC 3 amps, and switch off the ac source when the voltage is at its maximum. I can build a magnetic field using AC and then, when I switch off the voltage it would create an output in the ignition coil. This idea is right?
I would build a special circuit for switching off the AC power when the voltage is at its maximum.

Theoretically that might work, but it is a lot harder to do than you might think. It will require a lot of high power circuitry and fine tuning to get it to work. It is much easier (and cheaper) to just buy a new dimmer. Disconnecting the capacitor shouldn't have done anything to cause the problem, unless you allowed it to short somewhere. I've used this circuit on many occasions and it has worked great. I suggest you buy another dimmer (they're quite cheap, so it's no huge loss) and wire it up carefully, as per the diagram, and do not turn the switch all the way up. It should work towards the very bottom of the dimmer range, and will not work above, say, 10%. Also, try raising your capacitor value to .5uF, or even 1uF. I wouldn't recommend going much higher than 10 though, for safety reasons. The higher the value, the less touchy the dimmer switch will be, and the better the output.

Another thing, make sure your capacitor is NON-POLARIZED! Polarized capacitors can and will EXPLODE if you try putting AC through them!!!

J_Nichols · Feb 13, 2012

DerStrom8 said:
Theoretically that might work, but it is a lot harder to do than you might think. It will require a lot of high power circuitry and fine tuning to get it to work. It is much easier (and cheaper) to just buy a new dimmer. Disconnecting the capacitor shouldn't have done anything to cause the problem, unless you allowed it to short somewhere. I've used this circuit on many occasions and it has worked great. I suggest you buy another dimmer (they're quite cheap, so it's no huge loss) and wire it up carefully, as per the diagram, and do not turn the switch all the way up. It should work towards the very bottom of the dimmer range, and will not work above, say, 10%. Also, try raising your capacitor value to .5uF, or even 1uF. I wouldn't recommend going much higher than 10 though, for safety reasons. The higher the value, the less touchy the dimmer switch will be, and the better the output.

Another thing, make sure your capacitor is NON-POLARIZED! Polarized capacitors can and will EXPLODE if you try putting AC through them!!!

I asked you about building a circuit to switch AC at its maximum voltage because with that technique I get an effect that I cannot have with the dimmer. It's for other things.
I will try, for the last time, to light my desktop lamp with the dimmer because I don't see any damaged component, so I don't know where the short-circuit comes. If it fails, I will purchase a new dimmer.
The cap I used was non polarized. I will try a bigger cap, yes. The one I used was too little and maybe, for that reason, I didn't see any output at the coil.

AC driven ignition coil

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