Simple High Voltage Flyback inverter [without feedback coil]

Step 7 Creating the circuit

I used a breadboard to place the components on, but it's really not required, it's just easy to work with if you have it.
Alligator clips can move around and make short circuits. That's why I like to use as less as possible.

You'll have to experiment with the polarity of the primary winding. Choose a random polarity and test the output voltage.
Now change the polarity, and test it again.
Choose the polarity which had the best result.
(you can find the steps for finding the polarity in step 8)

Make sure that you connect the Negative side of the HV coil to the Gate, else it won't work.

The negative side is the side that doesn't shock you.
The positive side is the one you don't want to touch, and that shows corona discharges.

Comments

[geckomage]

I know this somewhat defeats the purpose of your instructable (which i will try tomorrow and see how well it works :) then post results) but do you know of any good way to detect a feedback coil in a flyback? im thinking of using a 20 volt 2 amp freq generator to make a square wave at around 20 khz and using an osciloscope to find which set of pins gives me the right wave form for the feedback ( i did get some crazy waves comin off of the secondary, but no arcing :[ )

[Electorials]

what do you mean with crazy waves? I hope you didn't connect your scope to the secondary, because it can only handle 400V max!

and I don't really know a good way for detecting the feedback. The only real way I know, is to apply an alternating voltage, of which you know that part is working correctly, to the primary windings. (like you said with the functiongenerator), and use a volt-meter to measure the AC feedback voltage. It should be just several volts, 1 to 3 volts I think.

[geckomage]

haha no worries. we have a pretty heavy duty oscilloscope aside from the regular ones and have several special probes for it. from bumping up really small voltages to where you can clearly see the waves to taking up to 30 kv and bumping it back down to see the waves without frying the osciloscope ;) (had a bunch of sponsors donate generously to fund the program) got a full electronics lab, the full autodesk, mastercam, and multisim swuites on some powerful computers. a full wood/metal shop with lathes and mig and tig welding machines included. also a large 3 axis cnc mill, a smaller 4 axis one, a smaller 3 axis prototyping one and a cnc plasma cutter. :) ill only have acess to it till the end of next semester though, so if you have anything you'd like me to try to build for a project that you'd like to test let me know ;D we have a circuit board printer too but thats not quite working yet :( and thanks for your speedy replies and advice! :D

[Electorials]

aah that's cool

and no problem ;)

[njkl44]

Hey thank you again i can finally play with high voltage EASILY!!! what is the voltage output on this thing (volts?)

[Electorials]

I think mine gives about 5kV
but I'm looking for what I can do to make it even higher.

I'm sure that a higher input voltage will do that, but I'll check my mosfet first, for the maximum ratings, and I'll have to recalculate the resistors.

[firedude20123]

usually 100,000 volts is feasible not sure how easily tho

[spark light]

100,000 volts is the opposite of feasible. especially for a flyback alone.
were you thinking of a tesla coil?

[Electorials]

indeed, it's impossible for a flyback to create such a high voltage.

[Wanderer.Anthony]

Maybe not alone, but a voltage multiplier on the output side might work.

http://en.wikipedia.org/wiki/Voltage_multiplier

[firedude20123]

actually it can, you just have to do it right, im not sure how but look it up online you'll see 100kv sparks

[spark light]

at 100,000 volts, the flyback will internally arc, causing a meltdown. i'm 100% sure it's impossible because the ferrite core will be an instant path between the two ends of the coil. even under oil, it is highly likely that it will arc internally. the most i've ever seen is about 70 - 80kv. anyone who claims they've gotten to 100kv is most likely optimistically overestimating.

[NPD2705]

I only see the 15+, where's the cathode ????

[Electorials]

cathode of what?

[NPD2705]

the cathode of the battery, there should be a line that connect to the 15-

[Electorials]

We take the cathode of the battery as reference, so we call ot 0v or GND.
There is no -15v if there already is a +15v.

What Is possible, is taking the anode as reference, so the anode will be 0v, and then the cathode will be -15v (15v more negative as the anode)

Now the answer to your question is: the GND (0v) at the bottom of the schematic, that's the other side of your battery ;)

[NPD2705]

thks, a lot :D

[Electorials]

No problem ;)
if there's anything else you need to know, just ask it here =)

[NPD2705]

hey can you tell me what the HV- is ? Is it the one with the sucken cup ?, and what's the negative side ? is it the plastic cover ? THKS

[Electorials]

the positive side (HV+) is the wire that comes out of the top of the transformer, with the sucken cup.

The negative side (HV-) is just one of the pins at the bottom of the transformer.

The plastic cover is no connection, it's just insulation.