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SSTC=Super Simple Tesla Coil?

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Marko

Tue Mar 28 2006, 08:28PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

EDIT: Err... can be an OLTC made with a heavy duty relay or SCR as mentioned above? (just another silly idea on a simple TC really.)

First tesla's resonant transformers ever were small multilayer coils, powered from few hundred volt supply and used kicker relay instead of spark gap.
In school I have similar small coil, uses only 24V supply and is supposed to generate maybe just couple of cm long spark.
It has diminutive topload, tunable helical primary, capacitor and relay as switch.
I never saw it in operation nor I remember details, so I cant tell more.

On any higher powers relay contacts would probably melt and weld shut, and it is also more inefficient than spark gap, and you aagain run in ''less than one turn priamry'' and other problems.

For SCR I concluded that it is big problem to turn it off.
FOr OLTC one could try to rectify mains halfwave, and make firing synchronous with halfcycle when 0V is present so SCR turns off when tank capacitor is rung to primary (now SCR would tend to turn off in ringing, and I dont know what side-effects would be) so idea prbably needs lots more of work.

Another could be using of GTO SCRs but they seem to be just too slow, altough I never saw that anybody tried OLTC with anything that is not IGBT.

dan

Tue Mar 28 2006, 10:06PM

Registered Member #223 Joined: Mon Feb 20 2006, 06:42PM
Location: Ottawa, Ontario, Canada
Posts: 125

The SCR wouldn't work for the tank circuit in a OLTC since it is basically a rectifier that you can turn on. It will cut off the other part of the cycle. (The back-emf would probably kill the SCR too). A triac would be able to conduct both ways because it is basically two SCR's in anti-parallel. However to my knowledge the switch-on/off time in both directions is too slow and you may get some overlap or something. Then again a triac may work in a OLTC if you had one big enough but if it could be use in a OLTC I'm sure someone would have done it by now. But then again a suitable IGBT and drive circuitry would be much better and just as simple. But the simplest TC by a long shot is a good old spark gap tesla coil. I mean it doesn't get simpler than a HV source, Spark gap, tank cap, primary and secondary coil. (and top load which technically optional)

Marko

Wed Mar 29 2006, 11:56AM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

The SCR wouldn't work for the tank circuit in a OLTC since it is basically a rectifier that you can turn on. It will cut off the other part of the cycle.

Its not different neither with IGBTs, and problem is simply solved by using diode in reverse.
Slowness of SCRs is main problem together with needed circuit design for right turnoff.

dan

Wed Mar 29 2006, 01:16PM

Registered Member #223 Joined: Mon Feb 20 2006, 06:42PM
Location: Ottawa, Ontario, Canada
Posts: 125

Yes the reverse diode across the SCR would work however it increases the part count. Also finding a triac that can handle more than a 100A is probably harder than an IGBT of equal size and simply not worth it because it's too slow anyway. But this thread is about using a light dimmer to drive a TC which as stated before wouldn't work well.

Dr. Dark Current

Thu Mar 30 2006, 05:39PM

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

Hi all,
today I've made a simple triac circuit driving a 8 turn TC primary in series with a 0.1uF cap. It was limited with a 25W light bulb that even didn't light up so it was drawing a very little current. I managed to make some 5mm sparks with a mini TC secondary (800T, 4 by 15cm).
I'll try to improve it soon for bigger sparks (less primary turns, bigger cap, bigger triac). I'm aiming for at least 20mm sparks, generated by "brute force"

J.M.

Marko

Thu Mar 30 2006, 05:47PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

you should use 1 turn and maximize capacitor as possible, if you can make it resonate and dont roast the triac maybe you can get few more mm.
I also gotspark around that size and decided it isn't worth trying any more.

GimpyJoe

Thu Mar 30 2006, 07:51PM

Registered Member #316 Joined: Mon Mar 13 2006, 01:30PM
Location: Marietta, GA
Posts: 212

I'm pretty sure you're just running the coil like a regular transformer with a bit of inductive kick from the chopped waveform out of the dimmer.

Teodor Zafiroski

Tue Apr 07 2015, 02:57PM

Registered Member #48007 Joined: Wed Jun 18 2014, 01:00PM
Location: Prilep, Republic of Macedonia
Posts: 33

Dr. Dark Current wrote ...

EDIT: Err... can be an OLTC made with a heavy duty relay

or SCR as mentioned above? (just another silly idea on a simple TC really.)

I know that I'm about 8-9 years late, but about a year ago, this post inspired me to make this:

TeslaHighvoltMan

Wed Apr 08 2015, 05:58AM

Registered Member #54545 Joined: Mon Mar 02 2015, 12:35PM
Location:
Posts: 2

Teodor Zafiroski wrote ...

Dr. Dark Current wrote ...

EDIT: Err... can be an OLTC made with a heavy duty relay

or SCR as mentioned above? (just another silly idea on a simple TC really.)

I know that I'm about 8-9 years late, but about a year ago, this post inspired me to make this:

? I don't think, that YOU made this! Please don't talk bullshit. The teslacoil shown in your link is a small commercial Teslacoil, produced in the former German Democratic Republic and was used at nearly every school for physics demo. You can buy this coils often on Ebay, here for example:

They can be run with 25V AC or DC, what makes them not very dangerous and they use the same simple principle like violet wand machines. So please don't say that YOU built this device

dex

Wed Apr 08 2015, 08:17AM

Registered Member #2566 Joined: Wed Dec 23 2009, 05:52PM
Location:
Posts: 147

Teodor Zafiroski wrote ...

Dr. Dark Current wrote ...

EDIT: Err... can be an OLTC made with a heavy duty relay

or SCR as mentioned above? (just another silly idea on a simple TC really.)

I know that I'm about 8-9 years late, but about a year ago, this post inspired me to make this:

How much arcing between contacts of the relay when it opens?

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