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Flyback transformer help

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Alex1M6

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Hi, I set up a flyback transformer to a basic 2n3055 pulse circuit and it works. except that I can only draw an arc of about half a centimetre (I am arcing to the pin that produced the longest arc).

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I am using 8 AA battery's to power it for 12v and I have tried 15v with no improvement.

Is this to be expected when using a single 2n3055 (it does have a heatsink) with batterys? as I have seen various youtube videos of people using this type of set-up and the arcs are much longer.

would this set-up work any better in terms of getting longer arcs
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Here is a photo of the flyback its self (I am thinking it looks like a small one).

DSC_4587 | Flickr - Photo Sharing!

Thanks!
 
use first setup, adjust R1 & R2 to tune it, and get a power supply that can do 1 amp @ 12v , you cannot use AAtype batteries, mine needs 2-3 parallel 9v for an inch of spark
 
Thanks,

By "tune it" do you mean use lower resistance value resistors?

and would 2 6v lantern type battery's in series be able to provide enough current?

thanks.
 
prolly, you need to check current ratings on batteries to be sure....

tune: I mean "tweak" so use a pot for R1(I used 500ohms) and a pot for R2(I used 100ohms) so you can find a perfect balance for them(sweet spot), DONT TURN THEM DOWN TOO LOW THOUGH OR U CAUSE SHORT CIRCUITS, they dont need to be rated for such high power(wattages)unless you go over 12volts, there is a sweet spot that optimizes efficiencies(could be 230ohm, could be 210ohm)....... on mine transformer there were 2feedback coils(i forget which one is best)

On mine it runs 750mA on 2x 9v batteries(I think) , and 1.33amps on a 12v supply....

also I used 2x 2n3055 in parallel config(not darlington pair) to eat some of the heat (heatsink may be good alternative), on the supply you can only run for 30seconds-a min and it will get to 60 celcius hot...

.........and.........be VERY careful most fly-backs have internal rectifiers and caps, so make sure to read up on all HVsafety
& DISCHARGEING...... and dont go pulling on wires while this circuit is active!...........
 
Hello, Alex1M6. Welcome to ETO!
For one thing, that circuit is designed for an older-style flyback transformer and usually does not work very well on the modern ones like what you are using. They are generally intended for transformers like this one:
**broken link removed**
I would recommend using a 555 timer circuit to power your type of coil. Here is one that should work very well:
flybackdriver.JPG
I realize this appears to be rather complicated, but it is definitely worth giving it a try.
Best regards,
Der Strom
 
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Sorry I have not replied in a while but I have been busy with other things.

Thanks DerStrom8 I will give that circuit a go at some point when I can get hold of those transistors and that MOSFET (sourcing supplies where I live is a real pain).

I think it is obvious now that I need a better power supply, and for me lead acid rechargeable batteries are my next best option as my parents have basically said no to using any electrical outlets.

I am able to charge lead acid batteries so that is not an issue, but I am just wondering if there is anything I need to know brand-wise and should I avoid certain cheaper brands, and for this sort of thing is there a maximum capacity (amp-hour) I should not go over for safety sake.

Thanks!
 
AA alkaline cells have internal resistance that reduces their output current and voltage.
But their max current is about 1A when new for a few seconds then the voltage drops. The voltage drops to about 0.9V per cell in 1 hour.

Somebody mentioned tiny 9V batteries. They have about 1/5th the capacity of AA cells because they have skinny AAAA cells inside.

Try the circuit using a powerful power supply.
 

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I have discovered something interesting whilst using a multimeter to measure current draw. the circuit will only draw 1.5A max @12V using 2 6v lantern batteries as the power supply.

could that be the cause of the poor output and what could I do to make the flyback draw more current?

Thanks.
 
Ok here is where it gets interesting, my two new 6v lantern battery's after about 20 minutes of play read 5.80V indicating that they must be almost dead. but I monitored the current draw and it did not go above 1.5A (I even had a 3A fuse in-line just in-case), and there are defiantly no short circuits anywhere.

strange...

Any ideas?

Thanks.
 
5.8 volts from a 6 volt lantern battery most likely does NOT mean it is dead. only .2 volts off? It might vary that much anyway, even when a battery is brand new.
 
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Sorry I have not really used these types of batterys exclusively for projects before, What voltage would you consider a 6v lantern cell to be dead. as the small to begin with arc from the flyback got shorter and shorter as the battery voltage went down.

So do you think it could just be a case of my particular newer style flyback not playing well with the 2n3055 transistor?

Thanks.
 
The point at which your cell may be considered "dead" depends on many factors, such as brand, type, etc.
As for the shorter and shorter arc, what kind of heat sink do you have on the 2N3055? It may be possible that there is something melting inside the transistor, but it is also possible that the battery was draining. Do you have a multimeter? It may be a good idea to test battery voltage while the circuit is in operation, just to see what is going on.
Der Strom
 
Here is a picture of the heat-sink the 2n3055 transistor is mounted to (there is also some thermal compound), I only run the circuit at a maximum of 20 seconds at a time and the transistor and heat sink get moderately warm but not to hot to touch.

Here are the images, and also my attempt at some "creative product photography" : )

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Thanks.
 
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You need to measure the battery voltage when it is powering the circuit.
 
You need to run 2 - 3 flybacks in series :p

JK but I remember when I was mucking around with flybacks, I had 2 connected in series (each running from the same driver circuit) and was getting a 60 - 70mm arc from 12v. The smell of ozone was strong. I wish I still had the photos.
 
Thanks for the replies, I can now get an arc to start at around 3/4 of an inch and stretch it to an inch using 3 6v lanterns in series for 18V. I think that is the most I am going to get using this set up.

I also soldered the driver circuit to a piece of verroboard and made some very high wattage resistors out of various different resistance value resistors in parallel for combined vales of 22ohm and 220ohm.

Here are some pics, (sorry the photos are not as eye pleasing as the last ones) ( :

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The wires are colour coded and grouped together starting with the pair to the far left being power and ground, the middle pair are for the feedback coils and the two on the right are the primary coil connections.

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