Post by: oneKone on June 25, 2017, 10:07:30 AM
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...
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Post by: CCX191 on June 27, 2017, 05:40:06 PM
Post by: oneKone on June 30, 2017, 03:08:09 PM
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.
Post by: oneKone on June 30, 2017, 03:57:39 PM
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....
Post by: CCX191 on June 30, 2017, 04:41:52 PM
I was planning to also make a PLL circuit to try out instead since my whole thing seems to be broken.
Post by: futurist on June 30, 2017, 08:27:02 PM
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
Post by: Mads Barnkob on July 01, 2017, 09:26:39 AM
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.
Post by: oneKone on July 01, 2017, 03:37:53 PM
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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Post by: Mads Barnkob on July 01, 2017, 04:55:41 PM
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!
Post by: oneKone on July 02, 2017, 01:46:19 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
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Post by: oneKone on July 05, 2017, 02:37:04 PM
before cleaning up
after cleaning up
Post by: CCX191 on July 05, 2017, 05:24:08 PM
Post by: Mads Barnkob on July 06, 2017, 09:29:48 AM
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.
Post by: oneKone on July 07, 2017, 05:38:56 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.
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.
Post by: oneKone on July 09, 2017, 01:15:16 PM
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Post by: oneKone on July 10, 2017, 03:54:58 PM
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At the moment it's running the 30n60s interrupted with the heatsinks cool to the touch.
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Post by: Mads Barnkob on July 11, 2017, 04:35:47 PM
A half-bridge of 60N60 minibricks can do 500A primary peak current. But do not push them much more than that.
Post by: oneKone on July 12, 2017, 01:47:33 AM
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.
Post by: oneKone on July 12, 2017, 02:32:15 PM
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Post by: Mads Barnkob on July 12, 2017, 09:02:07 PM
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.
Post by: CCX191 on July 13, 2017, 01:33:17 PM
Post by: oneKone on July 14, 2017, 01:29:11 AM
Nice PCB design! I was just wondering how to get the audio modulator to run off a optical fibre cable. Are there any relevant links or help that you can give?
Cheers,
I used the download page on the oneTesla site. They provide the Arduino code and schematics (for free) they even seem to stock the fibre receiver/transmitter cheaper than other places (for me anyways)
Post by: oneKone on July 16, 2017, 01:37:15 PM
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Post by: CCX191 on July 16, 2017, 03:41:30 PM
Post by: oneKone on July 17, 2017, 03:38:05 AM
That's really amazing! Seems like your toroid is made of alu tape? Always had struggles getting the tape to stick. But damn it was nice. Looking forward for your next build ! ;D
Cheers,
Yeah toroid is just a styrofoam ring with 25mm width aluminium tape, it stuck really well. There's an eBay seller that has a listing for a pack of spun toroids so I think my future coils will be based off the sizes of the toroid.
the next coil I think will be a fullbridge and maybe 160mm diameter and around 450mm in length.
Post by: Mads Barnkob on July 18, 2017, 02:32:33 PM
I also used the styrofoam toroids that can be found in hobby shops, with aluminium tape on, it was for my small DRSSTC2.
The smaller spun toroids are really affordable, so it is almost a shame not to buy them :)
Did you use regular 2- or 3-wire lamp cable for the primary coil? If so did you just parallel the wires inside the cable? I have not seen that used before.
Post by: oneKone on July 20, 2017, 02:01:51 AM
Good performance for a half-bridge, it struggles a bit to produce too many tones at once, it is much neater if you use single tone at a time music or MIDI edited to play only a single channel with the melody and backed by a small speaker.
I also used the styrofoam toroids that can be found in hobby shops, with aluminium tape on, it was for my small DRSSTC2.
The smaller spun toroids are really affordable, so it is almost a shame not to buy them :)
Did you use regular 2- or 3-wire lamp cable for the primary coil? If so did you just parallel the wires inside the cable? I have not seen that used before.
I think the problem with the midi was that I was messing around with the code from oneTesla and basically didn't know what I was doing.......
With the primary I bought a cheap extension lead for the wire, and you are correct with all 3 wires being in parallel. For whatever reason this seemed to give me the best output, it also has 3mm tube to give a constant gap between each winding.
Post by: oneKone on July 20, 2017, 02:06:11 AM
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Post by: CCX191 on July 21, 2017, 03:30:36 PM
Post by: oneKone on July 22, 2017, 12:55:24 AM
Sweet! I see that you have a CNC router. What sort of CNC is it? planning to get a small one to play around. Or maybe a laser cutter
It's a ripoff of a Zen tool works 7x7, I added a rc helicopter motor and an er11 collets. With that I get 22k rpm and can hold upto 7mm shanks. I'm currently working on a moving gantry router but I think it might take a while.
If you get a router you can always have a laser to bolt on/off if you use a diode laser for easy of use, I think they goto 5w now. This is my current build, it has a long way to go....
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Post by: oneKone on July 22, 2017, 10:38:38 AM
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Post by: Mads Barnkob on July 23, 2017, 10:36:16 AM
I can see that you found out how adding more topload capacitance increases spark length, this works until a certain point where the inverter/secondary coil can no longer feed enough energy to keep the top charged and it will start to run very unstable.
Like when I burned my primary coil due to secondary/primary flash over: />
Post by: oneKone on December 31, 2017, 07:00:07 AM
For a while I considered this project finished. But when the big sstc build came to an end I wanted to transform the small sstc. The controller is a standard PLL circuit, the gate driver is a classic 32/31 configuration but with bd139/140 totem pole config for a more robust switching method. I originally designed it like this because the driver chips became hot in cw operation with 60n60, but after a change to irfp460 MOSFETs everything runs very cool.
The original secondary lost about 60mm in height due to an arc over and it's running a 7 turn internal primary.
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Post by: Mads Barnkob on January 03, 2018, 10:37:38 PM
Is it old 5,25" hard drive platters as the topload?
Excuse me for not know that you were Chris on facebook, when I asked about using the picture for the guide ;)
Post by: oneKone on January 04, 2018, 02:59:43 AM
That looks real good, always nice to see a boxed up project!
Is it old 5,25" hard drive platters as the topload?
Excuse me for not know that you were Chris on facebook, when I asked about using the picture for the guide ;)
wow... tbh i don't think I've ever seen a 5.25" hdd. these ones were from 3.5" hdds i retired from my nas.
haha all good. it would be a complete stab in the dark to associate forum members to actual people.