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Registered Member #54503
Joined: Sun Feb 22 2015, 10:35PM
Location: New Zealand
Posts: 288
Im adding to this thread with construction photos and i will have the odd question or two since this is my first coil ive built :) -----------------------------------------------
------------------------------- Hi everyone, im new here and i come from down under in New Zealand.
Ive got a few questions here and LoneOceans has been very much help to me, but ive got alot to read up on here.
Basically i have wanted to do a tesla coil for some time and now that ive got some spare time after completing my other projects i was inspired by highvoltagefeathers tesla coil playing "sail" on youtube.
I want to build a similar spec'd coil to his, i would probably class it as a medium sized coil, with sparks over a metre long im guessing. His coil can be found here:
I want to work on similar specs, but if there is room for improvement i will improve on his.
Im looking at using: Secondary * 160mm diameter pipe * 524mm length (according to wintesla) * 2391 turns * 1207m of 32AWG wire * 101.45 KHz without toroid (according to what wintesla tells me) * 150x600mm toroid? I may make this slightly smaller, but larger the better i believe for a DRSSTC if i can use a smaller toroid i would rather do so, but my aim is to have it running around 75 KHz
Inverter * full bridge inverter using 2x CM300DY-12H IGBT's
Power supply * 230v 0-270v VARIAC @8A with voltage doubler should put out up to 540v, but have been advised it could be closer to 650v.
Driver: UD 2.7
Ok, so where do i start? lol
Basically i want to know if there is anything wrong with the above specs. My main concern is if 32 AWG is too fine for a medium sized coil, if more efficiency/power can be gained maybe i should go to the larger size of 30 AWG, as i dont think it will be much taller.
Im also unsure about the data provided in wintesla, everyone talks about JavaTC, but i cant get it to work because the values H1 and H2 for the secondary dont seem to be accepted, so i must be doing something wrong.
I want to work out if 524mm is the correct height for this much wire before cutting my pipe to the correct length.
With the primary im also wondering if 5/8" (8mm) pipe for the primary is better than quarter inch due to skin effect, it seems most people use this size. Im still unsure if i will need water cooling, but i see that this person is doing just that.
I understand that the radius of the inner primary winding should be 1 inch greater than that of the secondary, and that the spacings between each turn should be one quarter of an inch.
Are my IGBT's a good choice? Do i have to cut any wires inside these modules to disable current limiting?
With the power supply, im now uncertain of how much power such a coil will draw. Ive got a VARIAC, so i can always turn it down if it pops the circuit breakers, but basically in the USA he was running it on a 110v-200V VARIAC with a voltage doubler taking it up to 400V, his power supply was rated at 3000W. We have 230V here so i will have a higher working voltage, so i expect that the wattage would be around 1500w. My 8A VARIAC should handle a good 1800W, but i have been advised that my coil may be more powerful than this, if so i will look for a bigger VARIAC in the future to run full power.
My voltage doubler will be using 2x 4700uf capacitors rated at 450v, is this too high a capacitance, or is the larger the better? Im having alot of trouble sourcing these larger caps here, but i can get plenty at around 1500uf
I think this is all i can think of asking for now, but i will need more advice about choosing the right size toroids for the GDT's when ready, but i will be working on my primary and secondary coils for now before working on the rest of the electronics.
Registered Member #1403
Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968
Your numbers look fine at a first glance, for a more in-depth analysis of your separate components like IGBTs and DC bus capacitors, you should take a look at the DRSSTC guide I am currently working on:
There is no exact numbers for primary to secondary spacing or primary winding to winding spacing, this is all a part of getting your desired coupling between the coils, use JAVATC to calculate this, the advised coupling from JAVATC works well for a DRSSTC.
I have fed my DRSSTC1, 60N60 miniblock bridge, from a 10A 230V variac and I blew the 10A fuse and the coil could easily eat more power at high break rates.
I would advise you to use at least 8 mm copper tubing, quarter inch seems too small for a CM300 coil. It is pretty much standard to use 10 mm in Europe.
Registered Member #54503
Joined: Sun Feb 22 2015, 10:35PM
Location: New Zealand
Posts: 288
Mads Barnkob wrote ...
Your numbers look fine at a first glance, for a more in-depth analysis of your separate components like IGBTs and DC bus capacitors, you should take a look at the DRSSTC guide I am currently working on:
There is no exact numbers for primary to secondary spacing or primary winding to winding spacing, this is all a part of getting your desired coupling between the coils, use JAVATC to calculate this, the advised coupling from JAVATC works well for a DRSSTC.
I have fed my DRSSTC1, 60N60 miniblock bridge, from a 10A 230V variac and I blew the 10A fuse and the coil could easily eat more power at high break rates.
I would advise you to use at least 8 mm copper tubing, quarter inch seems too small for a CM300 coil. It is pretty much standard to use 10 mm in Europe.
I have been flicking through your guide and its rather helpful thanks :)
Yes i feel that 8mm (5/16) pipe is the better option, i dont think i will need water cooling from what i gather. I also have discovered that the IGBT modules i quoted are not suitable i need CM300DY-24h which are rated at 1200v
Im just wondering if the coil itself could be possibly too light using 32 AWG wire, would i be better of using 30 gauge?
I also thought this was a rather nifty bus layout here, ive never seen such a capacitor before, but it lends to a tidy construction. Fullbridge inverter of cm300dy-12h IGBTs by HighVoltageFeathers, on Flickr I wont be able to use such capacitors unless i can find one that is rated at a higher voltage of 650v or more, so i expect i will need to put 2 capacitors in series instead on a larger laminated bus.
I have seen what i did wrong in javaTC also. I was working in mm instead of cm! Anyway my resonant frequency is coming up to around 59.82 KHz which is actually lower than what i was expecting.
Registered Member #30656
Joined: Tue Jul 30 2013, 02:40AM
Location: UK
Posts: 208
My coil has broadly similar specs (also very similar to loneocean's DRSSTC 3), and worked okay with 600V IGBTs and the primary circuit tuned for low Z, but does run better with 1200V IGBTs.
Off the top of my head specs of mine are: 160mm dia, 700mm winding length ~1900 turns 0.315mm wire 160mm x 740mm dryer duct toroid (rather fragile unfortunately) 11 turn 1/4" copper pipe primary 48x 2uF 1000V Aerovox snubbers for MMC (two parallel x 24 series strings, can adjust number in series to change tank capacitance) CM300-24H full bridge with voltage doubler rectifier UD2.5 driver with some mods
Have gotten strikes to nearly 2.5m without popping it, didn't get a chance to try for more before heading to europe.
Feel free to ask questions about NZ suppliers of stuff - I'd also offer you some surplus parts except that they're all packed away under my parent's house right now :(
Registered Member #54503
Joined: Sun Feb 22 2015, 10:35PM
Location: New Zealand
Posts: 288
Hydron wrote ...
My coil has broadly similar specs (also very similar to loneocean's DRSSTC 3), and worked okay with 600V IGBTs and the primary circuit tuned for low Z, but does run better with 1200V IGBTs.
Off the top of my head specs of mine are: 160mm dia, 700mm winding length ~1900 turns 0.315mm wire 160mm x 740mm dryer duct toroid (rather fragile unfortunately) 11 turn 1/4" copper pipe primary 48x 2uF 1000V Aerovox snubbers for MMC (two parallel x 24 series strings, can adjust number in series to change tank capacitance) CM300-24H full bridge with voltage doubler rectifier UD2.5 driver with some mods
Have gotten strikes to nearly 2.5m without popping it, didn't get a chance to try for more before heading to europe.
Feel free to ask questions about NZ suppliers of stuff - I'd also offer you some surplus parts except that they're all packed away under my parent's house right now :(
Thanks for your reply. Yes if you know any good NZ suppliers, im keen to know, i really am after bus capacitors mainly, i dont think i will be able to get any suitable tank capacitors here in NZ unless you know of a source, i was going to get mine from eastern voltage research.
I will be using CM300DY-24H modules, i initally thought that all CM300 were rated at 1200v
My other question is really if i can get as large sparks using a finer winding on the secondary, if a heavier gauge wire will give me a higher output then i guess i may as well go this direction.
Registered Member #30656
Joined: Tue Jul 30 2013, 02:40AM
Location: UK
Posts: 208
For tank cap I bought these: I think I paid 120 USD for them (including shipping within the states) plus ~110 NZD them forwarded to NZ via youshop (big box made the forwarding pricey). Lisa at CTR surplus was helpful giving me an estimate of shipping size/weight before I ordered them.
For the DC bus cap I scored a bunch of RIFA 4700uF/450V electrolytics which were going to be scrapped (along with many IGBTs), so can't really help there.
Your secondary wire does sound a little finer than required, but I'm sure it would work. My secondary ended up about the same frequency as you're aiming at despite using thicker wire (due to the increased ~70cm winding length). There is apparently no magic number, just don't get the DC resistance or the frequency too high to reduce copper/switching losses respectively.
If you haven't already bought it, I think my wire came from CMG Electric Motors in Avondale, Auckland - went in there in person and they tried their best to find a part reel (only needed <1kg, full reels are ~3kg) and when they couldn't find one they gave me a good price on the full reel ($65ish). Again if I were home I could sell you what I have left, but it's too well packed away to tell others where to retrieve it from :(.
Registered Member #54503
Joined: Sun Feb 22 2015, 10:35PM
Location: New Zealand
Posts: 288
Hydron wrote ...
For tank cap I bought these: I think I paid 120 USD for them (including shipping within the states) plus ~110 NZD them forwarded to NZ via youshop (big box made the forwarding pricey). Lisa at CTR surplus was helpful giving me an estimate of shipping size/weight before I ordered them.
For the DC bus cap I scored a bunch of RIFA 4700uF/450V electrolytics which were going to be scrapped (along with many IGBTs), so can't really help there.
Your secondary wire does sound a little finer than required, but I'm sure it would work. My secondary ended up about the same frequency as you're aiming at despite using thicker wire (due to the increased ~70cm winding length). There is apparently no magic number, just don't get the DC resistance or the frequency too high to reduce copper/switching losses respectively.
If you haven't already bought it, I think my wire came from CMG Electric Motors in Avondale, Auckland - went in there in person and they tried their best to find a part reel (only needed <1kg, full reels are ~3kg) and when they couldn't find one they gave me a good price on the full reel ($65ish). Again if I were home I could sell you what I have left, but it's too well packed away to tell others where to retrieve it from :(.
Wire shouldnt be a problem for me, the person from Coils and Transformers here in Tauranga, has all the wire i need. My main issue ive discovered with the finer wire is mainly the short coil height i will have, since this coil was originally going to be run at around 400V bus voltage, it means that its output is much lower with sparks probably only around 1.5m, but running a higher bus voltage of around 650v will mean more powerful sparks, which i wont necessarily get the benefit from because the ground plane is closer to the toroid and most sparks will be striking the strike rail, so i dont think i will get as many long streamers that i want. 1.5m sparks are still pretty decent, but im now thinking its better for me to take advantage of our 230v mains, use 1200v rated IGBT's and make the coil a bit taller to allow longer sparks. The price difference between 12H and 24H IGBT's is not much, so its silly not to make the coil more powerful since im spending this money.
I will be getting my tank capacitors from eastern voltage research, they are the cheapest place to get the famous CDE 942C20P15K-F series caps.
Registered Member #54655
Joined: Thu Mar 19 2015, 05:56PM
Location: BC, Canada
Posts: 82
Hi, nzoomed, I just have a quick question. Where are you getting your ud 2.7 driver? Or are you building your own? Because if I ever build a big drsstc that's probably what I would want to use.
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Building my first DRSSTC - Updated thread...
