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Interesting SSTC circuit

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Wolfram

Fri Jun 15 2007, 05:08PM

Registered Member #33 Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971

While browsing around, I found this:

Here's some of the relevant information in german:

The circuit is quite unlike any other SSTC circuit I've seen, and judging from the pictures it seems to work quite well.

I might try out the circuit if I have the time later today.

Here's a video on YouTube:

Ken M.

Fri Jun 15 2007, 05:57PM

Registered Member #618 Joined: Sat Mar 31 2007, 04:15AM
Location: Us-Great Lakes
Posts: 628

WOW, thats the guy who has the 24v SSTC on youtube that puts out quiet a bit of power.

Edit whoops I didn't otice the link to youtube. LOL

Wolfram

Fri Jun 15 2007, 08:13PM

Registered Member #33 Joined: Sat Feb 04 2006, 01:31PM
Location: Norway
Posts: 971

I'm trying to understand the circuit now (MiniTesla 2). This is what I have come up with so far:

The 555 acts as an interrupter, along with R5, R6, R7, C8 and P1.

R8, R10, C10, Z2, T5 and T6 seem to be some sort of discrete voltage regulator. What does T5 do?

T4 turns the coil off by grounding the gates of both switching FETs through D3 and D4.

D4, D3 and D7 clamp the FET gate voltage to the voltage from the discrete regulator + 1.2V

D1, D2, Z1, R1, T1, C1-3 and C5 perform some sort of clamping on the MOSFET drain voltage, or?

The main power stage is a push-pull stage, and gate drive is provided from secondary base current through TR1.
R2, R3, D5, D6, D10-14 and C6 are there to bias the gates, right?

C4 and L4 form a parallel resonant circuit that helps the gate drive (?). The resonant frequency of this LC network has to be tuned to the Fres of the secondary.

Feel free to correct me and/or add to this theory.

Anders M.

Ken M.

Fri Jun 15 2007, 09:24PM

Registered Member #618 Joined: Sat Mar 31 2007, 04:15AM
Location: Us-Great Lakes
Posts: 628

I think T5 acts like a frequency or interuptor circuit, c10 charges then discharges through t5 and 6, charging c9.

Coronafix

Fri Jun 15 2007, 10:35PM

Registered Member #160 Joined: Mon Feb 13 2006, 02:07AM
Location: Melbourne, Australia
Posts: 938

Isn't it using a feedback coil to get the resonant frequency?
That's at first glance.

Ken M.

Sat Jun 16 2007, 02:08AM

Registered Member #618 Joined: Sat Mar 31 2007, 04:15AM
Location: Us-Great Lakes
Posts: 628

Actually...yes I think its got maybe a current transformer that reads the secondaries frequency and feeds it straight into the 2 fets, this is of course through some kind of transformer, and then its fed to some to some other circuitry, at least thats the way it looks.

Coronafix

Sat Jun 16 2007, 02:47AM

Registered Member #160 Joined: Mon Feb 13 2006, 02:07AM
Location: Melbourne, Australia
Posts: 938

I think the 555 serves to start the circuit and once it's running via it's own feedback in
push-pull operation, T5 and T6 hold the 555 off somehow.
C4 & L4 look like a grid leak tank.
I don't know a lot about electronics so forgive me if I'm way off.

Bennem

Sat Jun 16 2007, 06:07AM

Registered Member #154 Joined: Sun Feb 12 2006, 04:28PM
Location: Westmidlands, UK
Posts: 260

Hi Anders M,

It was good to meet you at this years Nottingham Teslathon!

Yes...i too came across this guys web site a few months ago,
and i think you are correct in your circuit description.
I was going to try and make his 24 volt version,
but have not got around to it yet.
To make it operate off 24 v i was just going to put
a 7812 regulater instead of the zener and transistor he used.
But....his 12-24volt coils sparks are impressive for such low operating
input voltage....

Coronafix

Sat Jun 16 2007, 11:09AM

Registered Member #160 Joined: Mon Feb 13 2006, 02:07AM
Location: Melbourne, Australia
Posts: 938

I've become fascinated with this circuit, thanks for sharing Anders M.
The sparks he is getting are soooo impressive.
As I've said, I don't know a lot of electronics, everything I know I've taught myself over
the years, so if anyone (both Steve's?) can clarify what is going on here it would be much appreciated.
Is it just me or is that a novel way of using a bridge rectifier?
I have been looking to build my first SSTC for a while and had gathered
together some information as to what I can build, as in Australia we have 240V mains
and a distinct lack of the parts that you Yanks have, well we call them differently anyway.
This circuit though seems ultra simple in parts, I've got some FETs from an old UPS that will
work for this application out in the shed. No need for FET drivers or PLL chips or comparators.
Do you think this could be scaled to run at mains rectified voltage?
I have to be honest though that I haven't got my head around zeners yet, and their function. I have a feeling that Z2 plays a major part in switching off the 555 once the feedback kicks in. Is this correct?

Ken M.

Sat Jun 16 2007, 01:35PM

Registered Member #618 Joined: Sat Mar 31 2007, 04:15AM
Location: Us-Great Lakes
Posts: 628

Yes indeed, considering most of us who have built SSTC's only get the little corona haze or make a class E with 50v in or so, and yet this guy can run it as low as 18v and STILL get SG\DRSSTC arcs off the topload, I too will one day try this design but for now its off to finishing the big boy, considering I have all the drive electronics tested, the GDT running fine (I think and Hope).

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