Author Topic: My sstc 1 build log (Read 16028 times)

oneKone · « **on:** June 25, 2017, 10:07:30 AM »

After a few small zvs drivers and extremely simple sstc's I wanted to make a proper sstc. I saw loneoceans sstc how-to guide and that inspired my driver (essentially based off his)

Because of work the progress will be slow but hopefully steady. The main two things I've accomplished this weekend have been designing/routing the control PCB and mocking up the interrupter on a breadboard, which is based on one Tesla's as interrupter. I'm currently drawing the interrupter to be as a shield for the Arduino Uno.

Hopefully I get some time during the week...

CCX191 · « **Reply #1 on:** June 27, 2017, 05:40:06 PM »

That's looking clean. Looking forward for more updates!

oneKone · « **Reply #2 on:** June 30, 2017, 03:08:09 PM »

Ok, so the driver chip and igbts are dead..... Triple checked the gate drive phasing and no error. Ran it on 120vdc and it had little output (maybe 40mm running interrupted). Igbts were cold but driver was hot on failure, run time was about 20 secs. I was running the gate driver at 15v and am wondering if this lead to failure.

One thing I can understand is that I've had this driver running with success on a breadboard about 4 months ago. Only difference is that now I have a proper driver/half bridge board.

The other crappy part is the ucc37321/22 pairs from rs is $50 not to mention irfp460. Maybe trying to throw some stuff together I should just follow something tried and trusted like Steve wards sstc5.

oneKone · « **Reply #3 on:** June 30, 2017, 03:57:39 PM »

I've just had a thought!
I've got most of the parts to make a pll circuit and some Chinese irfp260 mosfets to see if the glad bridge section/ gdt is the problem....

CCX191 · « **Reply #4 on:** June 30, 2017, 04:41:52 PM »

Yeah. RS or online parts for UCCs and IRFPs are really expensive. Though sourcing them in my local component stores are cheaper except that they don't provide UCCs. How about getting it from element14? I always get my components there, perhaps it's cheaper?

I was planning to also make a PLL circuit to try out instead since my whole thing seems to be broken.

futurist · « **Reply #5 on:** June 30, 2017, 08:27:02 PM »

I buy parts from TME, they are much cheaper than mouser and digikey but they don't have some of the parts
I suggest you don't even buy fake chinese stuff, mosfets and igbts are of extremely low quality.. 600V rated ones will probably fail at 120V
From 5 40N60's I received from ebay, one was missing a collector leg and from the rest I assembled dual halfbridge which I still need to test to a point of failure

Mads Barnkob · « **Reply #6 on:** July 01, 2017, 09:26:39 AM »

Welcome to the forum and great looking board

Do you have more pictures of the power electronics or video of when it failed?

I noticed that you did not ground the unused input pins on the 74HC14, this will give you trouble and most likely the 74HC14 will not work at all. This was dicussed only a few days ago in this thread: https://highvoltageforum.net/index.php?topic=93.msg431#msg431

Unfortunately there are not many places that can source the UCC driver chips, I have tried to substitute them with Maxim parts, but they have less options and lower performance, so they were okay for small coils, but other than that I went back to UCCs.

oneKone · « **Reply #7 on:** July 01, 2017, 03:37:53 PM »

Cheers for the reply guys, element14 seems to be the go. I'd much rather buy single pairs rather than 5 pairs at the moment.

Mads, yep I read that post aswell. Unfortunately the error occurred even with the input pins grounded...

So I decided to push ahead with a pll driver and bd140/139 gate driver, I didn't have a suitable core for CT feedback so I used a 74hc14 antenna feedback instead. Unfortunately the chinese irfp250s died as I thought they would, but it was from running them at higher than rated voltages. At least I now know the half bridge is correct.

Sorry about the crappy quality.

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Mads Barnkob · « **Reply #8 on:** July 01, 2017, 04:55:41 PM »

A MOSFET will not tolerate over-voltage, remember that you properly have high switching transients too, in a Tesla coil I would always advise on have 1/3 of the voltage rating as overhead.

Over-current is somewhat more tolerable from good cooling and short run times. But since you are running CW that is already pretty harsh on them

Great little coil with some star wars!

oneKone · « **Reply #9 on:** July 02, 2017, 01:46:19 PM »

Quote from: Mads Barnkob on July 01, 2017, 04:55:41 PM

A MOSFET will not tolerate over-voltage, remember that you properly have high switching transients too, in a Tesla coil I would always advise on have 1/3 of the voltage rating as overhead.

Over-current is somewhat more tolerable from good cooling and short run times. But since you are running CW that is already pretty harsh on them

Great little coil with some star wars!

cheers,
i was aware that pushing the mosfets past the voltage rating would kill them.... i just wanted to see how far they could be pushed considering they were chinese. gotta have a bit of fun!

I've ordered the ucc37322/21 drivers and a pair of irfp460 mosfets from element14 so hopefully they wont take overly long to get here. here's the pictures of the half-bridge section

oneKone · « **Reply #10 on:** July 05, 2017, 02:37:04 PM »

i haven't really been doing much on the sstc driver lately as i'm waiting for the new ucc3732x drivers to arrive. I ended up ordering from rs components after i found element14 wanted to charge $14 (aud) shipping.... that's two irfp460!! so i'm waiting on a pair of irfp460 and 5 pairs of the ucc3732x drivers. The little work i have done has been on the driver logic. this basically shows how i draw circuits to be isolation milled, there are way more efficient ways to draw but i find this easy. My design is far from perfect to some people but for me its fine.

before cleaning up

after cleaning up

CCX191 · « **Reply #11 on:** July 05, 2017, 05:24:08 PM »

Nice. Element14 has a one day free delivery shipping service in my country. Order by 5pm and you get it next day by 1pm pretty good service they have here somehow. But IRFP460s are super overpriced so I get them from my local component stores.

Mads Barnkob · « **Reply #12 on:** July 06, 2017, 09:29:48 AM »

Shipping prices are also the reason that I only order parts from RS, farnell, mouser etc if I can not find it anywhere else. We got one small electronic parts supplier left in Denmark, www.el-supply.dk which have good prices on the small stuff, but power electronics and special ICs gets very expensive. Often I resort to do a mass buy from mouser in Sweden and simply just spend the money on 30x UCCs or so, to hit a price break.

Did you remember C5 and C6? The decouple capacitors for the driver ICs, I can not really see them in the layout, they should be mounted right next to the ICs.

Are you just making the router layout in paint or is that some special program? I also used to make 90 degree corners, but now I only make 45 degree, it won't really make a difference, but gives you more space when you make boards with many traces. This is from a Universal driver 2.1 made for single sided PCB.

oneKone · « **Reply #13 on:** July 07, 2017, 05:38:56 AM »

Quote from: Mads Barnkob on July 06, 2017, 09:29:48 AM

Shipping prices are also the reason that I only order parts from RS, farnell, mouser etc if I can not find it anywhere else. We got one small electronic parts supplier left in Denmark, www.el-supply.dk which have good prices on the small stuff, but power electronics and special ICs gets very expensive. Often I resort to do a mass buy from mouser in Sweden and simply just spend the money on 30x UCCs or so, to hit a price break.

Did you remember C5 and C6? The decouple capacitors for the driver ICs, I can not really see them in the layout, they should be mounted right next to the ICs.

Are you just making the router layout in paint or is that some special program? I also used to make 90 degree corners, but now I only make 45 degree, it won't really make a difference, but gives you more space when you make boards with many traces. This is from a Universal driver 2.1 made for single sided PCB.

Good catch! C6 is there but for some unknown reason C5 isn't.... There near the numbers. I haven't flipped the circuit yet so imagine looking straight down at it.

The software I use is called vectric aspire, I use it for some of my projects but mainly for rc plane servo horns. Your PCB board looks very clean! I think on one of your sstc posts on your site you use express PCB? I don't suppose you'd be keen to email the file to see if I can mill it out? If successful I could even send you some. But I do understand if you don't want to release them as it looks like quite a bit of development has gone into it.

Quote from: CCX191 on July 05, 2017, 05:24:08 PM

Nice. Element14 has a one day free delivery shipping service in my country. Order by 5pm and you get it next day by 1pm pretty good service they have here somehow. But IRFP460s are super overpriced so I get them from my local component stores.

It seems irfp460 are a killer for most people. Tbh I think that's what makes second hand and fakes so popular, don't get me wrong I've also used second hand and fakes for some projects. I only wish there was somewhere local that's stocks the parts that I need.

oneKone · « **Reply #14 on:** July 09, 2017, 01:15:16 PM »

Got the PCB board made, now waiting on the MOSFETs to come. Not much to say really so pictures! The only thing I'm thinking for the next revision is to buffer? (Don't know the correct terminology) the output from the fibre receiver through the 74hc14.....

oneKone · « **Reply #15 on:** July 10, 2017, 03:54:58 PM »

Got some presents in the mail today! 3 x loneoceans Universal drsstc bare PCB boards, 2 x 30n60 and 2 x ixgn60n60.

At the moment it's running the 30n60s interrupted with the heatsinks cool to the touch.

Mads Barnkob · « **Reply #16 on:** July 11, 2017, 04:35:47 PM »

I got a feeling that you are upgrading this coil to a DRSSTC now

A half-bridge of 60N60 minibricks can do 500A primary peak current. But do not push them much more than that.

oneKone · « **Reply #17 on:** July 12, 2017, 01:47:33 AM »

Quote from: Mads Barnkob on July 11, 2017, 04:35:47 PM

I got a feeling that you are upgrading this coil to a DRSSTC now

A half-bridge of 60N60 minibricks can do 500A primary peak current. But do not push them much more than that.

Hahaha, to be honest this one is getting finished off as a standard sstc, so far it's been reliable so it should make a perfect demo coil. I think for now I'll keep collecting the parts to make a drsstc and continue to make sstc and learn a bit more....... Hopefully saving silicon in the process.

oneKone · « **Reply #18 on:** July 12, 2017, 02:32:15 PM »

So tonight I started and finished! my add-on board for the driver. It's just the fibre receiver, 74hc14, resistor and led for status. The idea came when I connected a small speaker to the output of the fibre receiver and wasn't impressed with the noise (Hi-Tec I know) after that I connected it to a 74hc14 and was impressed with the clarity of the output. For some reason I didn't check anything with an oscilloscope....

Mads Barnkob · « **Reply #19 on:** July 12, 2017, 09:02:07 PM »

It always a good idea to buffer the input to a good clean square wave and you have that nicely done with that cute little board on top of the other. Now there is also room for a screw to hold the opto housing in place

Good call on building more SSTC before moving to DRSSTC, it will pay off in the end, less mistakes to do on a more complex coil.

High Voltage Forum · « **Reply #19 on:** July 12, 2017, 09:02:07 PM »

Author Topic: My sstc 1 build log (Read 16028 times)

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