First Brick Coil - CM200 Half-bridge / Tesla Coils / Forums

Forums

4hv.org :: Forums :: Tesla Coils

« Previous topic | Next topic »

First Brick Coil - CM200 Half-bridge

1 2 next

Move Thread

LAN_403

loneoceans

Tue Apr 30 2013, 04:17AM

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

Good evening everyone!

For the past few months, I've been trying to steal as much free time I can between school to work on my second DRSSTC. Yesterday I finally plugged in the power and got the sparks going, so I thought I'd like to share my progress with everyone. Over the next few weeks, I'll be tuning the coil more and optimizing it's output. :)

Update

Here's a video of it in action running 208VAC in :)

First Revision

The project began when I bought two Toshiba IGBT half-bridge modules on ebay, good for 150A 600V. The original plan was to build a compact and powerful DRSSTC running this full bridge, with about a foot long secondary. The coil also uses a revised version of Steve Ward's UD2 as the driver. After many months of work, I finally got everything put together. Unfortunately, initial tests were worrying, and I soon found out that one of my IGBTs was half-dead. With the lack of time and money, I wasn't able to continue with these bricks.

8695229700 Bd50d5d667 Z

Above shows the primary during the construction phase. Note my SSTC1 in the background! The primary is press-fit so the copper tubing just pops into place.

Revision 2

I managed to get hold of a CM200DU-24F 200A 1200V IGBT and decided to make a half-bridge coil instead. The CM200 bricks are larger, so I wasn't able to fit a fullbridge inside the box I had already made. Finally, this worked perfectly and everything came together.

Preliminary Tests

Here's a photograph of the coil in action today. Initial tests were disappointing but it's surprising how much difference half a turn of the primary can make.

8694055185 C721d0ba3a Z

Specifications:

CM200 Half Bridge

140VAC input

13" x 3.5"Secondary, ~2000 turns

16" x 4" Toroid (I want to get a spun one someday)

150nF MMC

So far I'm happy with the results, but because I'm using 1200V IGBTs, I should be able to push it with much higher voltage on the bridge. I have a 240V step-up variac on hand and will be using that to test shortly. I'd like to thank the people on this forum for the great information as well as Steve and Philip for their fantastic advice. :) I'll be updating the progress here.

Feel free to check out my flickr here

Or my website (page still being constructed)

Physics Junkie

Tue Apr 30 2013, 04:25AM

Registered Member #7267 Joined: Tue Oct 16 2012, 12:16AM
Location: Detroit, Michigan
Posts: 407

Looks awesome. I bet you could double that output with some fine tuning and that step up transformer like you said. You could also try a voltage doubler with the step up to easily get 600V. Anyways, good job and good luck

Graham Armitage

Tue Apr 30 2013, 02:52PM

Registered Member #6038 Joined: Mon Aug 06 2012, 11:31AM
Location: Salado, TX
Posts: 248

That's a classy looking coil - very nicely made. Will be interesting to see what it delivers when you push the limits a little

You take some awesome photos - they are fantastic. If the Tesla thing doesn't pay the bills you can always shift to photography !! What camera settings are you using (if you don't mind sharing)

loneoceans

Tue Apr 30 2013, 10:55PM

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

Bushman wrote ...

That's a classy looking coil - very nicely made. Will be interesting to see what it delivers when you push the limits a little

You take some awesome photos - they are fantastic. If the Tesla thing doesn't pay the bills you can always shift to photography !! What camera settings are you using (if you don't mind sharing)

Yes I hope to power it with 240V sometime very soon, and we'll see how that goes. Also, I really hope to get a nicer toroid.

Thanks for the comments! Yes I also do photography as a hobby, and could write a whole long post about photographing these coils. It really depends on what aspect of the coil you want to show, as well as the lighting. So in one photograph, there's basically two things to take note of. 1, the background and overall illumination, and 2, the sparks.

Depending on how bright the sparks are and how bright the background is, I set the camera differently. All of them are of course taken it manual. I usually expose for the global illumination first, to ensure that I can see the coil and background without the sparks, then using the same settings, adjust the coil.

I have a push-button switch on my interrupter which only sends the signal when I push it down, so I can control how much sparks I want in the photos.

In this case, I wanted to capture the sparks as pretty bright sparks. To do this, I set the ISO fairly high and open up my aperture. Because the background is very dim, I have to expose the shot for a long time also, on the order of 4 seconds.

If I turn on the coil continuously for 4 seconds, all the sparks would be over exposed, so I only turn it on for about a second or so during the shot. That's basically how I do my photographs.

Example settings:

- Thick looking sparks - ISO 1600, F2.2, 1.6 seconds
- Normal looking sparks - ISO 1250, F3.5, 4 seconds
- More spark detail - ISO 400, F3.5, 10 seconds

Like it said, it really depends on the output of your coil and the brightness of the room. Does anyone want to know more? I could start a post on how I take my Tesla Photos.

loneoceans

Tue Apr 30 2013, 11:00PM

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

Here are some photos of the build you have an idea of what's inside:

8696296907 E8bd4e540b Z

My original Toshiba 150A 600V IGBTs. Unfortunately these ebay modules were not good. :( I'm very pleased with how I had them laid out, but I can only use the half-sized bricks for this. Does anyone have CM300DU-12F or similar half-sized modules they are willing to sell to me?

Regardless, in order to fit everything in the same box, I made a new half bridge with CM200 and a voltage doubler.

8696297067 783e93876d Z

It's all integrated so all I need to do is plug in the GDT to the driver, the AC in and output the the primary.

HV Enthusiast

Wed May 01 2013, 12:08AM

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

Really nice work! Thanks for sharing. Great photography too! I really like how the arcs hit and spread out on the floor. Very cool!

Graham Armitage

Wed May 01 2013, 03:36PM

Registered Member #6038 Joined: Mon Aug 06 2012, 11:31AM
Location: Salado, TX
Posts: 248

I would enjoy a quick photography thread - we all take pics of our work and knowing a bit more will be helpful. What you gave already is helpful. Thanks.

Myke

Thu May 02 2013, 11:24AM

Registered Member #540 Joined: Mon Feb 19 2007, 07:49PM
Location: MIT
Posts: 969

Looks great

There's this thread already for pictures:

loneoceans

Fri May 03 2013, 07:03AM

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

Some updates! Since I'm running 1200V IGBTs here, I could definitely do a lot better than the 120VAC I get from the mains. Unfortunately, the workshop I'm in seems to have their step-up variac missing, so I have no choice but to use a transformer. Unfortunately, the the step-up transformer I found is small (slightly smaller than a small MOT) and can't keep up with the current draw, limiting to only driving the bridge with the bus cap.

8704281208 E2b08c7c0a Z

I went up to 200VAC in today as quick test but it was apparent that I was quickly running out of space! Strikes to the floor were very common, but when it didn't, it easily made 4 feet of spark, which is impressive considering that the secondary coil is just slightly longer than a foot. I also tried pointing the breakout point upwards, but it seems that my toroid is too rough (and dented) that it wants to break out and hit the floor instead. More to come! :)

Steve Conner

Fri May 03 2013, 10:43AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Very nice

do you know what the operating frequency is?

1 2 next

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