Flybacks you say?..

A small update, I don't have a picture of it but it's something i'll leave to the imagination at this point. A little bit ago I went to the thrift store and bought a few things that I found randomly. Two fo the things were useful, the third has yet to be determined. One of these things was a larger white modern flyback transformer. I was suprised to see it in this little briefcase with other random electronics. I got it and without even increasing voltage or winding my own primaries around the ferrite I was arcing easily over 1 1/4"

I though it was neat, especially since there's so much potential that it's arcing to the other pins from my connected ground pin. If i really wanted to be creative i could put the two i've got in series, but I don't feel like building another driver circuit. that and I lack the parts, because as soon as I gutted my old soldering job i tossed the board with the rest of the parts I didn't want to bother de-soldering.

Okay, i'm done for now
/bored

Schematic

Okay, so I was asked to put up the circuit I'm using for this. Here's the layout:




That's the initial layout, as you can see it's pretty basic and like i said before it only runs from 12V DC. An addition to this circuit is to add a voltage regulator and filter capacitor before the 555 and a snubber in parallel with the primary of the transformer. That way I could power it up to a larger voltage and a larger output. However, I'm going to be switching things up and since I've got my feet wet with this project I'm going to go a different route ultimately, and here it is:


That circuit will ultimately be a better choice in order to achieve the higher voltage. It'll make for a full wave AC output which can be connected to the voltage multiplier. As an added bonus this circuit is also self oscillating, that means I don't have to worry about tuning it, it automatically find the correct frequency to work properly.

Now to go screw with the transformers I tore out of that T.V.

Shocking! not really but it's a start :)

Okay, so this is my layout pre-soldier, yes it's messy but go to hell the FET's pins don't fit into the proto-board. I replaced the larger resistor (5kish) with a 10k potentiometer so that it's fully tunable, if i wanted to I could utilize this circuit with just about any transformer that I want a half wave signal out of.


Figuring out why I was burning my MOSFET's wasn't hard to figure out, take a look at the sheer size difference between these two.


Yes, that is a large paper clip holding my FET to a copper heatsink from a computer.


After soldering everything together, having a really bad failure. Round 2 ensues and here's the result:


Like the layout? I sure as hell do because I suck ass at board layout, and I cut the crap out of my fingers drilling through that heatsink to mount the FET.


So here's the final layout before I box everything up, the reason I haven't done so is because I can push more out of this flyback although it's not necessary as this is just a test run to experiment. Right now it runs on 12v, I'm thinking I can push it towards at least 18 - 24 volts, the problem is that I need to solder in a voltage regulator and a snubber to reduce the risk of frying everything that is actually sensitive. Once again, not totally necessary for the final project but still a personal goal to get the best out of a small package.


SUCCESS! I hear a whine from the flyback and FET, voila!




Yeah, yeah it's not really impressive. That picture has it at around 1 - 1.5cm. After I took the pictures I tuned the circuit a little and was easily getting over 2cm (remember, this is ONLY AT 12V!).
That candle in the background? Yeah I lit it with the solid plasma arc (low power arc welder ftw)

Also a few things of note:
1. This is using a cheap ass flyback out of a dell monitor I got at IKEA for 10$.
2. After prolonged use I think the heat got to the FET and reduced it's efficiency enough to actually reduce the arc that was produced, if you're making one of these remember that this isn't exactly the most efficient circuit. That's a lot of power being wasted!

I'll post the circuit I used and some neat upcoming things to play with (new transformers I tore from an OLD television set).