gdt design questions

[niels]

 Hi Everyone!

After I’ve built my first Tesla coil I noticed that building the gtd right is probably the hardest part!
I found some of the shelf gdts like this one: 760301301 from würth electronics it would solve many problems like leakage inductance, and it also can be operated with quite a low frequency before it reaches its magnetic saturation. Now I'm wondering whether these transformers are even suitable for building Tesla coils. If it is, then is it possible to connect two of them in parallel to be able to drive a full bridge instead of only a half bridge or are the parasitic elements to high then? Also, I'm interested why it is common practice to hand wind the gdts do they preform better in some aspects?

Thanks in advance for your help!

[davekni]

That 760301301 transformer should work for smaller TO247 IGBTs or FETs.  It has much higher leakage inductance than a well-constructed hand-wound GDT.  Twisted wire pairs have about 660nH/meter, and a GDT can be made with less than 1m of wire.  760301301 specifies 4uH leakage inductance, a result of it's small physical size.

[niels]

Thanks for the reply!
I think I keep winding Gdt by hand although I’m curious to try out how the bought one preforms

[Zipdox]

What problems are you running into with hand wound GDTs? You just said it's difficult to make them. Do you mean you can't source the parts or do you have trouble winding them?

[John123]

I'll just leave these here:
http://www.richieburnett.co.uk/temp/gdt/gdt1.html
http://www.richieburnett.co.uk/temp/gdt/gdt2.html
http://www.richieburnett.co.uk/temp/gatedrv.txt
http://www.richieburnett.co.uk/temp/gdt/ferrite.txt
http://www.richieburnett.co.uk/temp/gdt/ferrite2.txt

[niels]

Thanks for the answer and the links they are really helpful!

I have no specific problem making gdts when having the right parts and following a good tutorial it is definitely doable, but I still think it is the hardest part to make just because you can mess up the most. Furthermore, it is very hard to impossible to specify how good your transformer is without expensive test equipment, a problem you don’t have to face when buying an already wound one as you have all your specs devined in a data sheet. Also, buying the gdt makes building a tesla coil more like plug and play as you “just” have to connect everything. But the huge leakage inductance is a reason for me not to use it

[John123]

Do you need core part number recommendations?

[niels]

Do you need core part number recommendations?

Yes that would be awesome and maybe also for other’s pretty useful
My driver is 12 volt and the resonant frequency of the coil is a bit over 100khz
Thanks!