stupid transistor question for a flyback ignition

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JDP12
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Thu Sep 20, 2007 6:37 pm

alright so i read the article in spudwiki about flybacks, then read the how-to guide that it linked to, okay fine.

here comes your idiotic question of the day... how does the thing get activated? I mean i know transistors can be used as a switch somehow, but how would it worked hooked up to a remote ignition thingy? and in the wiring diagram, where do those two wires go off to that say high voltage??

thanks, sorry for stupid questions, i'm not exactly electric circuit inclined...
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Fnord
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Thu Sep 20, 2007 9:17 pm

I'm assuming you have a flyback atm. If you don't this will be kinda hard to explain.

This is how to set one up:

You need to find the leads for 2 separate coils on the bottom first. This can be done using the diode check function on any multimeter.
You'll get a reading when you touch the two ends of one of the coils.
You won't know which of the two coils this is until you experiment awhile. Both sets of coil leads are usually next to each other somewhere near the bottom of the horseshoe pattern.
If you've wired all the coils/components up right, you will hear a whine when you hook a battery up to it.


The high voltage lead is the big fat wire coming from somewhere. To find the other end of the circuit, you'll need to hold it close to the leads on the bottom until an arc jumps to one. Avoid allowing it to jump to any of the coils, as you will fry your flyback.


I don't know if this will help any, but I'll explain how they work. Or at least how I think they work (just talking out of my ass here).

When you put current into it, a magnetic field is built up around the primary and feedback coils. When they become charged fully, the transistor is triggered and shuts off the circuit. The field collapses, and a high voltage current is induced in the secondary coil as a result.

After the field has collapsed the transistor lets current though again and the cycle repeats.


Where the hell is Jimmy when you need him.
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jimmy101
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Fri Sep 21, 2007 11:50 am

ilovetoblowthingsup wrote:how does the thing get activated? I mean i know transistors can be used as a switch somehow, but how would it worked hooked up to a remote ignition thingy?
See the circle with the plus sign on the left of the spudwiki diagram that says "6-24 V DC"? That is your positive power supply connection. Could be batteries or a wall wart or whatever you have to supply the voltage. The wart's (or batteries') minus wire goes to the circle with the "-" in it. To turn the circuit on and off you just connect and disconnect the power source. A switch would be a much better way to do it, see the drawing below.
ilovetoblowthingsup wrote:and in the wiring diagram, where do those two wires go off to that say high voltage??
Those go to your spark gap.
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crappy drawing showing changes to the nice spudwiki drawing of a flyback ignition system
crappy drawing showing changes to the nice spudwiki drawing of a flyback ignition system
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JDP12
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Fri Sep 21, 2007 4:15 pm

so basically to create the spark, i would just flip the switch?
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Sat Sep 22, 2007 12:07 pm

ilovetoblowthingsup wrote:so basically to create the spark, i would just flip the switch?
Yep, when the "Trigger switch" is closed sparks jump beteen the electrodes.
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