Ignition system

Mecke · Thu Apr 12, 2012 8:14 am

Hey!
I have been trying to build an ignition system with an ignition coil i buyed, But the problem is that i only get an small spark from it. And i have no clue why?
I attatched a picture that shows how i have been wiring it!
I use 12V as a power source and i have been trying with higher voltages but with no success

Do you guys know what im doing wrong?

And another question, how do you add prewievs on the post?

Petitlu · Thu Apr 12, 2012 8:36 am

your diagram is not correct!
I just finished with an ignition coil is working well, here's the diagram:

Mecke · Thu Apr 12, 2012 8:56 am

i dont get how the diode is wired, can you please explain?

Petitlu · Thu Apr 12, 2012 9:03 am

I did not have a diode so I have not placed and it works well!
sorry for my english, I'm French

Mecke · Thu Apr 12, 2012 9:08 am

whats up with the capasitor and the transformators... i dont get it

Alster370 · Thu Apr 12, 2012 9:18 am

Correct me if im wrong but, to me it looks like the camera circuit is charged up by the 12v battery, which when the circuit is armed, discharges the cap and that is sent to the ignition coil which ramps up the voltage to deliver the spark.

Petitlu · Thu Apr 12, 2012 9:19 am

the capacitor is a circuit Single Use Camera
the diode is not connected to a transformer but on a car relay
Here is a link that may help you also:

http://www.spudfiles.com/forums/how-to- ... 23160.html

Mecke · Thu Apr 12, 2012 9:23 am

Thanks, i think i get it now!

Dident se that it was an realay

Petitlu · Thu Apr 12, 2012 9:24 am

no, the flash has its own supply of 1.5v

EDIT : With pleasure!

dewey-1 · Thu Apr 12, 2012 2:31 pm

Petitlu wrote: I just finished with an ignition coil is working well, here's the diagram:

Happy to see you made use of that revised diagram I did for you.
The diode across the coil is just a good design practice on inductive loads.
It will make the contacts of low current switches last longer.

Petitlu · Thu Apr 12, 2012 2:37 pm

Thank you again for the diagram!

jimmy101 · Thu Apr 12, 2012 5:13 pm

Your basic circuit is OK, you are just missing one thing. You need a cap across your switch. That's how an automotive ignition circuit is setup and the cap is very important. IIRC, you need about an 0.1 MFD cap rated to tens of volts? Technician will probably chime in with the correct cap rating.

The circuit will throw a spark every time the switch is opened. If you want a simple oscillator type circuit you can replace the switch with a relay wired as a "buzz coil" (Google it). That setup will give you something like several hundred sparks per second.

The photoflash board circuit will work as well but really is a lot more complex than needed. The 12V battery + switch + automotive ignition coil + cap has been used literally trillions of times to ignite fuel air/mixtures. The big advantage of the photoflash board is that it'll operate from a AA battery for a fairly large number of sparks. The simpler coil/switch/cap setup takes a much beefer 12V power supply.

Petitlu · Thu Apr 12, 2012 5:30 pm

In the diagrams dewey-1, the switch activates the relay so there is not much power ... I walk the control relay with disposable battery 12v ...
there is no switch on the high voltage.
the advantage of flash is the size

dewey-1 · Thu Apr 12, 2012 7:02 pm

The diode suppresses the inductive back emf which can be a higher voltage than the switches can handle. Think of a higher voltage arc.

See this explanation:
http://en.wikipedia.org/wiki/File:FlybackExample.GIF

Petitlu · Fri Apr 13, 2012 1:47 am

ok I understand
I put a 1N4007 diode (because I have no 1N4004) and the relay does not phase began with, so I removed ...
Some diagrams show a "spark gap", which he has used?