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SGTC or DRSSTC?

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coillah

Mon Jul 07 2008, 03:27PM

Registered Member #1517 Joined: Wed Jun 04 2008, 06:55AM
Location: Chico CA
Posts: 304

For my first tesla coil?

I just bought an oscope

Arcstarter

Mon Jul 07 2008, 05:06PM

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

coillah wrote ...

For my first tesla coil?

I just bought an oscope

I would definitely have to say sgtc. It will give you the idea of what tuning challenges in tuning you might come across, and you will not blow something up if you dont have the right tuning. Also, it is quite a bit easier to make sgtc and could be much cheaper. I would then go to sstc, but that is just me. I say this because sstc can just consist of a 555 and mosfet or as difficult as a drsstc, without the capacitors. I really dont know anything about the drsstc but it is the most difficult(or maybe oltc, i am not sure, but i made an oltc before and i still don't know how a drsstc works) type of tesla coil to build.

:P

J. Aaron Holmes

Mon Jul 07 2008, 06:36PM

Registered Member #477 Joined: Tue Jun 20 2006, 11:51PM
Location: Seattle, WA
Posts: 546

Arcstarter wrote ...

I would definitely have to say sgtc.

Agreed. And that's not to say SGTCs are universally simpler; there are many practical challenges that seasoned coilers enjoy taking up over and over. There have been real advances in the art of SGTC construction in just the last few years. However SGTCs are much more forgiving of simplistic design processes, and are therefore the quickest route to "something." (unless you can't get parts for some reason)

Cheers,
Aaron, N7OE

coillah

Mon Jul 07 2008, 07:31PM

Registered Member #1517 Joined: Wed Jun 04 2008, 06:55AM
Location: Chico CA
Posts: 304

OK so I read this thread a little too late and got outbid on a nice looking NST.

I found another NST, can someone tell me if this is a good choice? It looks like a decent deal, 15kV 30mA, no GFI, tested and works, on/off switch. 50 bucks +25 for shipping.

It looks like I'm gonna take everyone's advice and build a SGTC first, that way if I mess up it won't be the end of the world.

One last thing, when I build this thing, how long can I anticipate the streamers to be? (with the above transformer)

J. Aaron Holmes

Mon Jul 07 2008, 08:40PM

Registered Member #477 Joined: Tue Jun 20 2006, 11:51PM
Location: Seattle, WA
Posts: 546

$50 isn't terrible. They'll show up cheaper from time to time. You might call around to some local sign shops just to see if you can avoid the shipping charges. That is, if you care. Worked for me back in the day (got a buddy who works at a sign shop and gives 'em to me free now

).

A 15/30 will make a fine Tesla coil. You can reasonably expect streamers in the 2+ foot range.

Cheers,
Aaron, N7OE

coillah

Mon Jul 07 2008, 09:15PM

Registered Member #1517 Joined: Wed Jun 04 2008, 06:55AM
Location: Chico CA
Posts: 304

well, shoot I already bought it... shipping and all, it comes to around 75$ which I feel is kind of expensive but oh well.

any suggestions for where to look for capacitors? or should I just build an MMC bank?

Arcstarter

Tue Jul 08 2008, 01:17AM

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

coillah wrote ...

well, shoot I already bought it... shipping and all, it comes to around 75$ which I feel is kind of expensive but oh well.

any suggestions for where to look for capacitors? or should I just build an MMC bank?

Well an mmc would be alot better in mine and some others opinions, because they are sometimes cheap and if one fails, simple replace. I would suggest getting some of these:

You would need 20 of them for 7.5 nf which is perfect for a 15kv 30ma transformer, so it will cost a little more than 100 bucks, but it will most likely not fail for quite a long time. You will have 4 left in case one of them fails. They are self healing, so just turn the power off if one fails and it will heal, iirc. Tesla map says you should get about 36.6 inch sparks if you have a big enough coil, is tuned correctly and you have thick wiring and all that good stuff. Read

and

and you might find some good capacitors for cheap. You might be surprised how cheap it may be for such low capacitance.

The capacitors should be rated for around 40kvdc or just 20kvac. If you find a good capacitor and it is rated for dc voltage, divide the voltage by two and that is the ac voltage rating. You want a few or more kv safety margin. If you go by that and you find some good caps or use the cde capacitors, you might as well say you have a bullet proof cap. Not uite, but they will be quite long lasting.

coillah

Tue Jul 08 2008, 03:02AM

Registered Member #1517 Joined: Wed Jun 04 2008, 06:55AM
Location: Chico CA
Posts: 304

OK, how did you calculate what my cap value should be? (this is the so-called tank cap right? aka primary)

coillah

Tue Jul 08 2008, 05:17AM

Registered Member #1517 Joined: Wed Jun 04 2008, 06:55AM
Location: Chico CA
Posts: 304

OK. Been cruisin around Ebay and found:

Suitable for an MMC? I was reading in my book that these caps are less than optimal for TC design as they tend to overheat and break easily. Also they have a large series resistance and power loss.

However they are cheap and I can get a great voltage and capacitance out of stringing them up. I can design a cooling case, and what not.
Or should I just get the mica caps?

Arcstarter

Tue Jul 08 2008, 05:27AM

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

coillah wrote ...

OK. Been cruisin around Ebay and found:

No, do not get those caps. They will not work good at all, i dnt think. I got some capacitors like that and i had 3 8kv caps running with 6kv input and they all exploded instantly. check out:

under developing my 4 inch coil. He had them fail instantly too. And what mica caps are you talking about? If you have the money, the capacitors i showed you are THE way to go. Or you can just build the capacitors from transparencies at:

I would advise you to get a capacitance meter to measure them. One of them with three transparencies only gave me 3.5 nf.

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