Author Topic: My first drsstc (Read 23147 times)

oneKone · « **on:** September 21, 2017, 05:14:54 AM »

So I'm already thinking of my next coil and I think it's time to tackle a drsstc. I still have a stupid amount to learn so I was going to start with something basic.

The two drivers I'm looking at are oneTesla and Steve wards sstc 5 for simplicity. I know people recommend the ud driver but to start with I'd rather build my own (still copying someones design) and learn from it. As for the secondary I was going to go with the kaizer drsstc ii.

The two drivers circuits:
http://onetesla.com//media/wysiwyg/downloads/tsschem.png
https://www.stevehv.4hv.org/DRSSTC-.5/DRSSTC-.5sch.JPG

Mads Barnkob · « **Reply #1 on:** September 21, 2017, 07:30:36 AM »

I would still advise against using the simple drivers, Steve himself advise against using his older designs, they have flaws, can be unstable etc.

The UD1.3 is still a very good driver, and still fairly simple: https://www.stevehv.4hv.org/new_driver.html

You need proper feedback circuit to ensure zero current switching and over current detection to save your silicon from exploding

There is my DRSSTC design guide, not complete yet: http://kaizerpowerelectronics.dk/tesla-coils/drsstc-design-guide/

and the MMC calculator: http://kaizerpowerelectronics.dk/calculators/mmc-calculator/

and ofc JAVATC: http://www.classictesla.com/java/javatc/javatc.html

If you have any questions to some of my guides or calculators, please do ask, maybe there is something I can explain better, in more detail etc.

oneKone · « **Reply #2 on:** September 21, 2017, 10:13:54 AM »

Quote from: Mads Barnkob on September 21, 2017, 07:30:36 AM

I would still advise against using the simple drivers, Steve himself advise against using his older designs, they have flaws, can be unstable etc.

The UD1.3 is still a very good driver, and still fairly simple: https://www.stevehv.4hv.org/new_driver.html

You need proper feedback circuit to ensure zero current switching and over current detection to save your silicon from exploding

There is my DRSSTC design guide, not complete yet: http://kaizerpowerelectronics.dk/tesla-coils/drsstc-design-guide/

and the MMC calculator: http://kaizerpowerelectronics.dk/calculators/mmc-calculator/

and ofc JAVATC: http://www.classictesla.com/java/javatc/javatc.html

If you have any questions to some of my guides or calculators, please do ask, maybe there is something I can explain better, in more detail etc.

Cheers for the advice and the links Mads. I'll take your advice and go with the universal driver. At least those blank ud 2.7c driver boards I bought awhile back can get populated!

oneKone · « **Reply #3 on:** November 07, 2017, 07:33:22 AM »

Now that my sstc is finished I can get a proper start on this project! I'm thinking of going 50mm diameter coil @ 200mm long. (Ratio taken from mads website) I have 36 awg wire thank I'll be using so as far as I can tell this rules out bigger coils?
As for the topload I'm thinking about going with this:
https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.de%2Fulk%2Fitm%2F282378468990

As for the driver, it's between China and aus..... It seems to be taking ages! So this got me thinking of making a modular ud 1.3b, like a 3 tier cube type thing.

Mads Barnkob · « **Reply #4 on:** November 07, 2017, 12:36:20 PM »

Secondary form and wire size is find to get a coil around 50k impedance, if you look at the spreadsheet linked on the secondary design page of my site, there are many more calculations in the outer regions of coils ratios, you would very quickly get a very high impedance secondary coil when making a larger coil with such a small diameter wire. ( https://docs.google.com/spreadsheets/d/1TkpvH7e5geHCIhB_Gr3egwL_THJYqjZIU5INoo54nD4/edit#gid=482293335 )

Topload looks perfect for the job.

A UD1.3b is perfect for small coils, there is no need for phase lead when the primary currents most likely are sub 500 Ampere. At-least it is still in a region where it can be dealt with by a larger heat sink

oneKone · « **Reply #5 on:** December 14, 2017, 01:04:04 PM »

So I finally made a start to this project! I setup a winding jig and wound the same secondary as mads drsstc ii. After winding I gave it a coat of polyurethane in the evening and a second coat the next morning..... Little did I know the moisture in the air and on the secondary left a bad orange peel, so naturally I tried sanding it off. This was the result

I was pressing too hard and it ripped a few windings off. A part of me is thinking that I might not have wound the coil that tight for this to happen.

So oh well, looks like I'll be winding another one! But I think I'll just can't this one in half and see how it goes as a sstc.

Mads Barnkob · « **Reply #6 on:** December 16, 2017, 03:14:21 PM »

What a bummer!

Did you use polyurethane on spray can? It looks like the finish I got when I used that. Best results are from brushing on.

I also started wrong out on my first DRSSTC secondary and had to cut off all the copper wire and start over

oneKone · « **Reply #7 on:** December 31, 2017, 06:43:50 AM »

Quote from: Mads Barnkob on December 16, 2017, 03:14:21 PM

What a bummer!

Did you use polyurethane on spray can? It looks like the finish I got when I used that. Best results are from brushing on.

I also started wrong out on my first DRSSTC secondary and had to cut off all the copper wire and start over

Hi Mads.
Yep the polyethylene was from a spray can. I've tried brushing water based polyurethane on without great success.

After having a bit of a break working on the house.... The backyard was a bloody mission! And I also wanted to get a small engine i designed/built a few years back running again, I finally now have some time for sstc!

The second coil was wound tighter and all spraying was done in the awesome Aussie heat! The brand of polyurethane I'm using is Cabot's oil based gloss. I've found this gives the best results.

One thing that I've realised is that I've wound the coil exactly to your drsstc ii you built, so at least I can have something to reference to throughout the build.

oneKone · « **Reply #8 on:** January 04, 2018, 06:48:29 AM »

I've finally received the driver board! Unfortunately they don't provide a pinout for the led header but I'm sure I can trace it back.

Hopefully after the work holidays I can go full steam with this project.

Mads Barnkob · « **Reply #9 on:** January 04, 2018, 01:45:23 PM »

Looking forward to see some sparks

The pinout of the LED header might be a copy from the UD2.1b schematic: http://stevehv.4hv.org/leadcomp/UD2_1revB/UD2_1revbschem.pdf

oneKone · « **Reply #10 on:** January 08, 2018, 06:11:34 AM »

Cheers for the schematic mads, your a lifesaver!

So because I am building your drsstc ii I can easily copy (although I'm going to do the calculations to see how these values came to be) the tank capacitance.

Unfortunately I'm unable to easily get the same capacitors you used but I can get these:
https://au.rs-online.com/mobile/p/polypropylene-film-capacitors/7441455/

I was thinking about using 3 in series to achieve 0.0733 uf @ 6kv.

oneKone · « **Reply #11 on:** January 15, 2018, 03:51:57 AM »

So I'm still waiting for parts to arrive so I thought bugger it! I need to test the secondary..... For reasons?

So I used the new sstc driver I made and the fullbridge from my big sstc. It's currently running a 3t primary and secondary current feedback. I am so keen when the parts arrive to get it running as a drsstc!

oneKone · « **Reply #12 on:** January 16, 2018, 02:12:51 AM »

I ordered a pair of my favourite cores! A pair of epcos n30 37.5x16.2 ferrite rings. For whatever reason the capacitors I ordered from rs have taken quite a while to come from the UK, but both orders should be here tomorrow!

Hopefully this weekend I can achieve first light as a drsstc..... Exciting times! But one thing I want to do is redesign the full bridge section. There's quite a bit of room for improvement and I intend to get it!!

Mads Barnkob · « **Reply #13 on:** January 16, 2018, 12:45:24 PM »

That is some pretty nice audio modulated sparks for a SSTC and even without a breakout point.

Running a SSTC without a breakout point causes a lot more stress on the inverter, but even more so on a DRSSTC, so only do that if you know what you are doing or can risk some blown silicon

oneKone · « **Reply #14 on:** January 21, 2018, 07:46:39 AM »

cheers mads, and thank you for the tip about using a breakout point.

I've successfully had the coil running as a proper drsstc! the average ark length to free air was about 280mm, Although i've had the bridge fail twice now due to over current. So i ordered some of my most love/hate relationship ixgn60n60's. hopefully after making a new half bridge i can get the same results as mads drsstc ii

oneKone · « **Reply #15 on:** January 25, 2018, 01:05:42 AM »

I was just wondering, would it be ok to set the OCD limit by using a variable power supply on the current transformer input?

Laci · « **Reply #16 on:** January 25, 2018, 02:57:39 PM »

Be careful with the power resistor at the rectifier,it might get pretty warm by the constant voltage-current.I experienced with this,it is working.

Mads Barnkob · « **Reply #17 on:** January 25, 2018, 06:57:41 PM »

Quote from: oneKone on January 25, 2018, 01:05:42 AM

I was just wondering, would it be ok to set the OCD limit by using a variable power supply on the current transformer input?

If you put a fixed voltage into the OCD CT input, it will only trip the OCD if you adjust the potentiometer below that voltage limit. You have no real measurement from the inverter then and no way of protecting it from blowing up.

oneKone · « **Reply #18 on:** January 26, 2018, 08:43:40 AM »

cheers for the info, i'll make another ct to measure the current with an oscilloscope.

i fired up the coil with the new ixgn60n60 halfbridge and was pretty happy! the only downside is that i'm currently using plywood to hold my pancake secondary. after playing a ghostbusters midi track the primary got quite warm so i'm going to abandon that idea! i think on monday i'll machine some slots in acetal rods. for the base of the frame i wanted to use polycarbonate or perspex but the material is a bit more than what i originally thought, so i think i'll try some plastic cutting board instead.

oneKone · « **Reply #19 on:** January 29, 2018, 11:09:18 AM »

Another small update.

My local electronics shop sells acrylic sheet 195mmx195mmx3mm for $14 a sheet, and a local plastic shop sells 10mm acrylic rod for $12 @ 2 meters, so I'm pretty stoked about the prices! I also bought some 1/8th (3.175mm) copper tube for the primary. I'm still yet to calculate the difference between the tube I bought and the wire mads used in his drsstc ii.

On a side note, this will make a perfect diameter hose for my small engines!

High Voltage Forum · « **Reply #19 on:** January 29, 2018, 11:09:18 AM »

Author Topic: My first drsstc (Read 23147 times)

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