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lbenson

Sat Dec 27 2008, 11:06AM

Registered Member #1756 Joined: Tue Oct 14 2008, 07:12AM
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Posts: 32

Hello, I am fairly new to the scene and are wishing to learn all i can and hopefully end up with an audio modulated tesla coil. I made myself sound stupid in an earlier post asking how i could convert my SGTC to audio modulated. Someone told me to hook it up to a clapper and place it next to a speaker, funny, but unhelpful. I know now only SSTC DRSSTC and VTTC can be audio modulated. if i left any out please let me know. So i have a few noob questions and really hope someone will answer them in a useful manner. I recently came across 2 books sold by EasterVoltageResearch.com one says its Minibrute specific and costs 42 or so, and the other just states its about DRSSTC and costs about 67 or so. I was wondering if anyone was familiar with these books. They seem to be a good buy to me. and i think they would help me out a lot as a noob. Perhaps if your familar with them you could tell me a little about them. Secondly im curious as to about how much in total it would cost to build a working audio modulated DRSSTC, perhaps there are minibrute kits available. either way what would be the cheapest audio modulated tesla coil to build. I see there are the Minibrute boards for sale on the site. is that just the PCB and do i find my own parts? im sure ill have more questions later. but in the meantime i would really appreciate some constructive input. I know im new and have much learning to do. but knowledge is what i seek, (not sarcasm). thx again

MRacerxdl

Sat Dec 27 2008, 01:28PM

Registered Member #989 Joined: Sat Sept 08 2007, 02:15AM
Location: SÃ£o Paulo, Brazil
Posts: 476

The EVR books are very good, I bought the "Building the Modern Tesla Coil", it have a good theory of how it works, of three models of DRSSTC.
About the prices, I am not a good reference but its arround US$150-200 the eletronic piecies and so, it might be high depend of the toroid that you use, and if all things goes right. But in first DRSSTC, normally things doesnt go right and some problems may happen and a few IGBT's can be blown. So its difficult to say how much you will expend with a DRSSTC.

I think for start, its better and Audio Modulate SSTC, its easier and cheap. But that is your choice.

lbenson

Sat Dec 27 2008, 07:26PM

Registered Member #1756 Joined: Tue Oct 14 2008, 07:12AM
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Posts: 32

Whats the difference between DRSSTC and SSTC?

Mathias

Sat Dec 27 2008, 09:03PM

Registered Member #1381 Joined: Fri Mar 07 2008, 05:24PM
Location: Hungary
Posts: 74

The simple answer would be : "Just a capacitor" XD

(that is in series with the primary L , if this LC circuit is "fed" at (near) resonance , the Impedance drops and maximum current can flow)

HV Enthusiast

Sun Dec 28 2008, 12:26AM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
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Posts: 3068

Operation is typically different as well. A conventional SSTC can run anywhere from CW to pulsed mode (typically close to CW but using half-rectified DC) whereas a DRSSTC is almost always run in pulsed mode for very short duty cycles (typically <5%)

Arcstarter

Sun Dec 28 2008, 02:41AM

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

I second you audio modulating a sstc, not drsstc. Sstc's are much easier most of the time.

The simplest audio modulated sstc would be

with the enable pin of both the ucc's connected to a zero-crossing detector, and that connected to the audio input. It would not sound good, however.

A better one for audio mod would be

mixed with

. Use the second schematic, but with the basic audio-mod section of the first one for bigger sparks, or just use the first one for smaller sparks. They are PLL so they are always in tune, and drawing arcs does not mess it up.

The problem with using sstc's for audio mod is that they have to be dc smoothed, and uninterrupted. That means more heating. which means either larger semiconductors or large heatsinks and fans or other means of cooling.

aonomus

Sun Dec 28 2008, 06:11AM

Registered Member #1497 Joined: Thu May 22 2008, 05:24AM
Location: Toronto, Ontario, Canada
Posts: 801

Having just built a SSTC modulator using the enable-pin method, the quality is pretty harsh, if you build a SSTC go with PLL, you'll get better performance.

lbenson

Sun Dec 28 2008, 09:36AM

Registered Member #1756 Joined: Tue Oct 14 2008, 07:12AM
Location:
Posts: 32

Lets say i went against your advice and went straight to the DRSSTC, Ordered all the boards and parts. assembled it 100% correctly. What sort of problems could/would i expect to run into?

Mathias

Sun Dec 28 2008, 03:42PM

Registered Member #1381 Joined: Fri Mar 07 2008, 05:24PM
Location: Hungary
Posts: 74

Not a very wise choice.

Why would you even consider that you will be able to "assembled it 100% correctly" ?

There will be instructions in the book, but by lacking experience and/or knowledge it still will be a difficult task. Not to mention if something goes wrong, parts can fail , or worse.

If you really want to build one so badly better get an oscilloscope :)

(btw when it will be "done", Do you really think will it worth all the time and money invested in it? Just search the forums and see for yourself how much drsstcs can cost and how frustrating it can be when it's not "working".)

MRacerxdl

Sun Dec 28 2008, 04:53PM

Registered Member #989 Joined: Sat Sept 08 2007, 02:15AM
Location: SÃ£o Paulo, Brazil
Posts: 476

There are much things that can go wrong, like, your secondary fres can be more or less than the specified on the book, because you can do more spaces at the turns, or use a diferent type of PVC/Acrylic tube for winding the coil, that can increase or decrease the inductance/capacitance of the coil, which changes the fres. And the topload, it can be a little bit different and changes the fres too.

So its not a simple thing, there are a few things that you need to adjust, a scope will help it a lot (without one, you will have problems like me, but I have a frequency counter, which helps a lot too)

And problems at DRSSTC generally means blowed IGBTS or so, and that is the expesive parts on a DRSSTC (considering only the parts that can blow).

So if you go to DRSSTC, take in mind that you can expend more money than expected.

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