Making 'fake-QCW' sparks with a SSTC / Tesla Coils / Forums

Forums

4hv.org :: Forums :: Tesla Coils

« Previous topic | Next topic »

Making 'fake-QCW' sparks with a SSTC

Move Thread

LAN_403

loneoceans

Sun Jun 15 2014, 05:36AM

Registered Member #4098 Joined: Fri Sept 16 2011, 09:26PM
Location:
Posts: 236

[Updated 16 June]

I managed to plug in the coil into 208VAC! It now makes healthy 12+" sparks!

14440409142 6a491a2076 Z

My logic transformer has taps for both 240/120V operation. 208V is enough to power my logic, too, so it all works out. Spark length is now over a foot long with a 5" secondary. I'm sure there is more to be achieved running a lower impedance primary (maybe winding it wider), and with 240VAC in, but I'm quite pleased with its output.

--

Hi everyone!

I thought this project went well enough for me to publish something!

I always liked ATX power supply boxes because they're everywhere, cheap, and standardized. And while the inverter inside is useful for powering computers, they can be a little bit boring after a while..

Atx Opened Small

So I thought, why not keep the box, but replace it with a different inverter that's more fun to play with! So I made a general purpose single PCB SSTC which fits almost all ATX power supply units! I took apart a few of them and confirmed that they had more-or-less the same sized PCBs inside, and designed one to fit the most common one. The board has everything needed to make an SSTC of your choice, or a DRSSTC with the addition of a tank cap. This way, I can wake up in the morning, decide that I'll like a new tesla coil, and have one all soldered up before lunch! I have a few more boards left, not sure if anyone is interested?

Board Barepcb2 Small

The board even comes with the following fun features such as an integrated logic supply transformer, fuses and undervoltage lockout, as well as a laminated bus accepting a half bridge of your favourite TO-247 IGBTs.

I also decided to add swappable interrupters that you can plug in and out like a graphics card does on a motherboard! It plugs it conveniently via an 8-pin socket at the side of the board. I made a staccato interrupter to make fake-qcw sparks, as well as an ATtiny SSTC interrupter together with a fiber input jack. They all take two standard potentiometers for pulse width and bps control.

Board Controllers Small

Then I made a small 2.8" x 5" secondary with a cute toroid I bought on ebay... and assembled quickly with acrylic cutouts and clear PVC pipes.

Structure Coils Small

And this coil structure attaches via magnets to the ATX case! The result is a very portable SSTC I can take apart and throw into my bag and bring anywhere I want to.

Reestc3 Mirror120 Small

A new coil is born! One of the goals of the project was to make sword sparks like VTTC or QCW coils, so I didn't install the bus capacitor and run it off a staccato interrupter. It's running at 120VAC now and happily makes 8-9" sparks at the moment. I'll be plugging it into 208VAC soon for more sparks.

This was a fun project and I have a few boards leftover. I'll be happy to hear some feedback on how you think I could improve the coil!

For more information, check out my website here:

where I have a writeup in progress with schematics and more details.

Thanks!

Sigurthr

Sun Jun 15 2014, 07:13PM

Registered Member #4463 Joined: Wed Apr 18 2012, 08:08AM
Location: MI's Upper Peninsula
Posts: 597

Awesome build! Extremely aesthetically pleasing!

How many watts is it running in CW mode (if that is an available mode)? I tried such small coils before but had problems running more than 80W or so CW.

hsieh

Mon Jun 16 2014, 03:50AM

Registered Member #1412 Joined: Thu Mar 27 2008, 04:07PM
Location: Taipei Taiwan
Posts: 278

Can you upload your board layout file? Thanks

Goodchild

Mon Jun 16 2014, 02:17PM

Registered Member #2292 Joined: Fri Aug 14 2009, 05:33PM
Location: The Wild West AKA Arizona
Posts: 795

This is a fantastic build, very clean and compact.

If I can I would like to point something out for future reference. Your D-flip flop is setup incorrectly if you are trying to terminate on zero crossings. The way you have it setup the interrupter is driving the asynchronous clear, this input on a D Flip-Flop doesnâ€™t care what the clk is doing when itâ€™s pulled low, it will always and immediately drive the Q low. In its current state you are more or less just using that flip-flop as a non-inverting buffer.

Antonio

Mon Jun 16 2014, 03:17PM

Registered Member #834 Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644

I am using these boxes for small drsstc drivers. Several components from the original power supplies can be reused too, as line filter, rectifier, bus capacitors, heat sinks, and the whole standby power supply to power circuits and the blower. The space is a bit cramped, however.

loneoceans

Tue Jun 17 2014, 05:19PM

Registered Member #4098 Joined: Fri Sept 16 2011, 09:26PM
Location:
Posts: 236

Goodchild wrote ...

This is a fantastic build, very clean and compact. If I can I would like to point something out for future reference. Your D-flip flop is setup incorrectly if you are trying to terminate on zero crossings. The way you have it setup the interrupter is driving the asynchronous clear, this input on a D Flip-Flop doesnâ€™t care what the clk is doing when itâ€™s pulled low, it will always and immediately drive the Q low. In its current state you are more or less just using that flip-flop as a non-inverting buffer.

Thanks Eric! I did however go through the logic table again. It is true that I'm driving the async clear'/reset'. Now Pre' and D are pulled high always. When the interrupter turns on (H), it is inverted and fed into CLR' (L). Output Q' is H and drives the enable turning the UCCs on. When my interrupter pulse ends (L), H is fed into CLR'. However nothing happens, only until the next rising clock edge from the feedback (and with D at H), Q'(n+1) then transitions to L turning off the UCCs, so this way the flip flop does terminate the pulse only at rising crossings. I think I did a quick ltspice simulation a while back just to make sure this made sense and it turned out as expected. I recall testing it a while back on a different driver and it works as expected as well. I'll be happy to know if there is anything wrong with my reasoning.

Antonio wrote ...

I am using these boxes for small drsstc drivers. Several components from the original power supplies can be reused too, as line filter, rectifier, bus capacitors, heat sinks, and the whole standby power supply to power circuits and the blower. The space is a bit cramped, however.

Yep this was exactly the reason why I decided to make a general purpose board for ATX power supplies. I really like how they usually all have integrated line filters with an IEC jack, switch and comes with a lot of nice cables. I don't generally take the components apart. I guess one drawback is the difficulty in adding large heat-sinks so those I have on my IGBTs are a bit smaller than what I would want, so I do limit the total duty cycle to a low maximum for reliability. The big fan at the top helps a lot though. :)

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob