[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [TCML] New list member
Hi, welcome to the list. I see that you were building Steve Ward's mini
sstc. I built that a while ago and i was having the same problems blowing
mosfets. Here are a couple suggestions for you to get it working. Make
sure the primary is not wrapped tightly over the secondary or you will have
flashovers and that can ruin your mosfets. Start with about 12 primary
turns wrapped on some 6" pvc pipe and decrease turns until your mosfets stay
cool. you also want a little leakage inductance so keep about 1 foot of
wire between the bridge and the primary coil it self. You also want to
check and make sure you are using 5000 permibility ferrite for the gdt and
use twisted pair wire for the gdt windings for low inductance or you will
get "ringing" on the gates and if the gdt waveforms are not a prety clean
squarewave that can lead to mosfet heating and failure. One last thing to
look out for is cross conduction of the mosfets were the second mosfet turns
on before the first mosfet has time to turn off. That would cause a dead
short for a couple of ms and that again can lead to failure. One thing to
stop that is to add some "deadtime" witch can be obtained by placing a
1n5819 schottkey diode in parallell with the 5ohm gate resistor. I hope
this helps you get the coil running. Good luck
On Sat, Jan 10, 2009 at 11:02 AM, Bert Pool <micro_wave@xxxxxxxxxxx> wrote:
> Welcome aboard, Rob!
>
> Judging from your photos, you are making good progress in coiling. Don't
> let the blown solid state parts stop you - we have members on this list who
> have blown IGBT's by the bucket full (literally.) My first solid state coil
> was a miserable failure. I'm working on my second, and I'm basing it on
> proven designs from people on this list. You will find this group has a
> very wide range of interests, but our moderator(s) do quite a good job of
> keeping things on topic!
>
> Good luck with your new coils, and never hesitate to ask questions or ask
> for some help - the people on this list are some of the friendliest and most
> helpful I've ever met.
>
> Bert Pool
>
>
> Robert Byron wrote:
>
> Hello,
>> My name is Rob and I am new to the list and fairly new to coiling. Here is
>> a picture of my first coil made from junk. It is powered by a 6Kv NST and I
>> used two sheets of aluminum foil with overhead transparencies for the
>> capacitor. I'm not sure on the secondary wire gauge as I unwound it from a
>> fan motor. The toroid is a wheel from my deceased R/C plane covered in foil
>> tape.
>>
>> http://flickr.com/photos/robbyron/2453129267/sizes/l/
>>
>> (snip]
>>
>>
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla
>
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla