Transistors & Flybacks / High Voltage / Forums

Forums

4hv.org :: Forums :: High Voltage

« Previous topic | Next topic »

Transistors & Flybacks

previous 1 2 3 next

Move Thread

LAN_403

Dr. Dark Current

Sun Apr 06 2008, 03:08PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

quicksilver wrote ...

Plasmaddict wrote ...

Edit- I forgot, of course you have to use an air gap in the flyback core

Do you have an example of a "core air gap"? Maybe I'm just being stupid on this but the term "core" is what I'm stuck on... thanks.

Core is the black ferrite part around which the cois are wound. You will usually see part of the core exposed, that is where you wind your windings.

The core is from 2 halves, and for this driver it is needed that you have a little gap between the two, ~0.5mm seems to work well. If you didnt disassemble the transformer then it will most likely have the gap.

Proud Mary

Sun Apr 06 2008, 03:20PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

quicksilver wrote ...
What I am trying to find as well is some method of recognition of the MOSSETs, etc that I come across to identify them.

If you don't know of it already, DataSheetCatalogue.com is a good place to start. Just enter the part number of the component into the search field:

Of course, some - but not all - monitor and TV manufacturers will have their own part numbers printed onto otherwise standard components, and as has been said, these can be more difficult to identify without a transistor analyser of some kind.

quicksilver

Mon Apr 07 2008, 01:56PM

Registered Member #1408 Joined: Fri Mar 21 2008, 03:49PM
Location: Oracle, AZ
Posts: 679

Harry, that Datasheet page is uniquely useful! That's what I had not been able to find. Thanks.

spark: The more I look at that page (I was quite impressed) the more I like it. BUT HOW were the core's separated from the originals? The way it appears, those core's are really glued in there. @ 15v the arc appears to be just as strong as any I've seen from the old toroid style. Good work. The idea to dissemble appeals to me from a learning standpoint but my gut says there must be some technique involved as the potting assembly is sure tough to work with.

Plasmaddict: On those new one's - I'd like to see someone dissemble them <grin>! That is actually what I thought you meant but it doesn't hurt to ask. -Someone mentioned that there is really no payoff winding a new primary on the newer designs in any instance....do you think that's true given the above (Spark's page) There doesn't seem to be any agreeing on the modality of a Primary. One fellow will say that the thing needs 4 turns to the tap, another says something else....Is this all a question of core design, size, & yield desired???

cbfull

Mon Apr 07 2008, 02:39PM

Registered Member #187 Joined: Thu Feb 16 2006, 02:54PM
Location: Central Ohio
Posts: 140

Just a couple of things I've found in my tinkering around. The air gap is not necessary unless your circuit oscillates at an audibe frequency. They can get pretty loud if the resonant frequency is too low.

I have tried using the transistor that came with the monitor before, and I got very unsatisfactory results. Thin arcs and the transistor got hot quick. That doesn't mean you will get the same results.

I used 2N3773's for years and never had a single problem. I can't believe I went that long and never made the switch to MOSFETs.

Someday..

Ultra7

Mon Apr 07 2008, 03:04PM

Registered Member #1157 Joined: Thu Dec 06 2007, 12:11PM
Location: Houston, TX
Posts: 307

quicksilver wrote ...

Identification of semi-conductors, etc. MOSFETs, diodes, & assorted goodies are often difficult to decipher as codes are altered from manufacturer to manufacturer.... With the use of flat screens on the majority of desktops now, the old CRT monitors will be a treasure trove of parts for a year or so until they all disappear. I wish there was a simple method to identify some of those parts aside from going to the various manufacturer's web sites and writing down all their codes to ascertain which code type was used, etc.

Another site I find useful for any number of reasons, among which is part identification, is Octopart.

I need a stack of components, but who has them?
Type in the component, hit search, and it will tell you who is carrying them, how many they have, what they will cost, list similar parts, and almost always a spec sheet on the part.

For those of us that have tried searching for a part on Digikey's website, this is a boon.
Give it a try, it's not often that it cant find the part I want.

Arcstarter

Tue Apr 08 2008, 01:24AM

Registered Member #1225 Joined: Sat Jan 12 2008, 01:24AM
Location: Beaumont, Texas, USA
Posts: 2253

it is actually very easy to make your own flyback transformer. I did it today and have EXCELLENT results! Just wind 100 turns on a 1 inch pvc pipe that will fit on the core. I know it sounds ridiculous because of so few windings but i used about 60 windings and i get like 10kv! I will make a video soon. Here is the website i found it on. It is german though.

Backyard Skunkworks

Tue Apr 08 2008, 04:57AM

Registered Member #1262 Joined: Fri Jan 25 2008, 05:22AM
Location: Maryland, USA
Posts: 451

Nice, I think I'll try and make a flyback soon. Nice size autotransformer too, I'll try and discharge a 300V cap into a 1:100 autotransformer and get a 30kV pulse.

Andyman

Tue Apr 08 2008, 06:53AM

Registered Member #1083 Joined: Mon Oct 29 2007, 06:16PM
Location: Upland, California
Posts: 256

Wow! I always thought flybacks had way more windings! Now I want to make my own!

Kolas

Tue Apr 08 2008, 01:22PM

Registered Member #102 Joined: Thu Feb 09 2006, 08:15PM
Location: Raleigh, NC
Posts: 169

yeah i've wound several flybacks, they are fairly easy to get the number of wraps you need. around 200-500 wraps is all you need!
what makes it a challenge as already states is the insulation. i've built many flybacks but none have ever lasted.

teslacoolguy

Tue Apr 08 2008, 02:29PM

Registered Member #1107 Joined: Thu Nov 08 2007, 10:09PM
Location:
Posts: 792

That's why you need to wind them single layer like a tesla coil to prevent corona breakdown and whatever other high voltage horror that could be in store for you

previous 1 2 3 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob