I said it would be much less than 1/2 amp. That was based on how much current gets through the 5 µF capacitor at 50 or 60 Hz and 240V or less.

That is on the 240V side so the power is less than 120 W.

The 15,000 volts is on the secondary side of the transformer. The turns ratio on an ignition coil is about 100:1, so 1/2 amp on the primary side will only give 5 mA on the secondary, which comes to a bit less power, certainly nowhere near 7,500 W.

 

ohh sorry my bad, i was thinking of wrong side of coil. Thanks for the correction. Well ive bought the ignition coil off ebay for $25 includ delivery, going to buy a dimmer switch and a high voltage non-polarised capacitor and put it together. Lets see how it goes.

 

Ahhh, i used to live in Melb., just moved to Cairns though.

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BTW adding a cap on the high voltage out will do you no good, it will make big loud sparks, you need continous arcs....

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ive just been talking to a family friend whos a qualified electrician and he believes that this circuit is incorrect and will no work. Would anyone be able to explain this circuit. i mean the car ignition coils normally run on 12v DC in the circuit it runs on 240v AC. Explanation please...what do dimmer switch and cap do so different. Aswell what type of dimmer switch is needed?

 

Ignition coils do not _HAVE_ to run on 12V DC, i have seen a few people running them from a 240V dimmer. The key to this is, the more complicated the circuit, the longer life your coil will have, Ideally you want to run it at aroun 12V DC, but they can handle a fair bit more than they are rated for.

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do you know exactly how this works?

Aswell what dimmer switch type should i use. A trailing edge or a leading edge dimmer switch

 

$25.00?

Only about $5.00 here, at most Auto wreckers.

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Just recieved the igntion coil today....alot smaller than it look liked over the internet, fits in palm. I dont know if voltages being produce from this would be enough..how would i test it?

i spoke to my advanced electronics teacher and he is confused aswell. AC voltage up to 240v is going into the igntion coil, where these things are built for 12v DC how does it work?

Attached Images

Bosch coil for electronic igntion 12volt HEC 716 .jpg (147.0 KB, 7 views)

 

dont worry i tested it with just a 9v dc battery and it produced a tiny spark. I measured the output voltage with a 500v digital multimeter and i got a max spike of around 1000volts. I only got a spark when i tapped the battery on and off... is this pulsed DC???

but i still need help with understanding the circuit. can anyone explain?

 

You need about 20,000V for a good spark. It is about the same for a car spark and a Jacob's ladder.

The turns ratio on a car coil is about 100:1 so you need about 200 V on the primary to make a spark. 12 V is not enough.

The primary resistance of a coil is quite low, so you cannot apply 200 V for more than a few microseconds.

In a car, the 200 V is generated like this:- 12 V is applied to the coil primary. The current builds up over a few milliseconds to a few amps and then the current is turned off quickly. The rate of change of current is very high. The voltage is the rate of change of current multiplied by the inductance of the primary.

The 200 V dies away as the current in the primary reaches zero and stops changing.

In the Jacob's ladder, 200 V is generated like this:- The triac in the dimmer turns on, and applies mains voltage to the coil.

The 200 V dies away as the motor run capacitor charges to 200 V and so no more current flows.

The dimmer turns on twice each mains cycle so 100 or 120 times per second.

 

ive been told that there are a couple types of dimmer switches witch do different things (trailing/leading edge). what dimmer switch do i require for this jacobs ladder circuit?
would this dimmer switch work http://cgi.ebay.com.au/New-3-Way-Wir...QQcmdZViewItem

as well, what size capacitor do you beilieve i should use?

 

aswell theres this one

http://cgi.ebay.com.au/ws/eBayISAPI....MEWA:IT&ih=007

 

im thinking of programming a chip to create a pulse of dc

Circuit has a chip connected to the base leg of a transistor. E and C of the transistor has 12v going through it to the ignition coil. The chip will be programmed to send a pulse to the base of the transitor 2 times a second. What do you think? How can i stop back EMF? Will the transitor get dammaged?

Thanks. Below is the schematic.

Attached Images

jacobs ladder chip schematic.jpg (771.6 KB, 9 views)

 

I just used to use two 2N3055 transistors hooked up so they oscillate and drive the input. Then used a coil from an old TV. But ignition coils work too. It was enough to get a huge spark going up two metal coathanger wires and making a good SNAP at the end.