Exactly right. Anything you (the OP) does now is ultimately meaningless because it will behave in a completely different manner once you do eventually transfer it to a PCB. Designing and building a DRSSTC is not a simple task, and soldering/desoldering IGBTs is probably one of the easiest parts of the process. Better get used to it.Which can also a be an artifact of the breadboard. I don't understand why that can't be understood in this?If you think all of your "work" will transfer when going to a true PCB after doing this on a breadboard, get ready to do it all over again there. It doesn't need to be "pretty" now, just off of a breadboard.
As I already said, you may not even notice the heating of the MOSFETs from the outside. The damage usually begins on the inside and works its way out. Also, because they act more as resistors in this sort of project, MOSFETs are extremely lossy and will not operate efficiently. They will waste power that would otherwise be transferred to your secondary coil, and will not contribute to the resulting output. Heating is definitely an issue (internal especially) but it is not the only issue. For some standard SSTCs MOSFETs will be sufficient because of the low primary currents, but DRs require much higher currents, and thus require IGBTs.I mentioned as soon as I can run this, see I am getting hot with runtimes increasing, I will absolutely switch to IGBT's and go to an Arduino board with proper pulsing. Then was the freewheeling diodes I mentioned I have external mur460's there.
You should never put a budget on a DRSSTC. Trust me on this one, I learned the hard way. I'm afraid to ask where you managed to find the parts for $20. What are you using for a capacitor bank? What are you using for heat sinks? What are you using for the primary coil? What are you using for the secondary coil? You have failed to provide even a photo of your setup, much less an in-depth description of the parts and the build process so far.So I do apologize I can't get u a waveform based on Equipment your used to but I've seen these made with less and I'm not going g to spend $500 on a 20$ project. I had every part new inboxes other than the IGBT's. That's what cost me 20$. I do understand I can't see things that may need to be, but like I said before can't you take the necessary steps to insure this won't happen?
All of which are very important and should be done ASAP.If I'm missing something please don't just leave me hanging I am taking everything into consideration. The only things I haven't done are swap out for IGBT's, shorten pulse width and buy a new scope.
Using the MOSFETs instead of IGBTs is as bad as using a breadboard instead of a PCB. MOSFETs behave in a very different manner than IGBTs do, so testing with them is useless because the coil will not work the same when you swap them out. As for DRSSTCs being done with MOSFETs, anyone who has actually built a DR will tell you that they are a poor choice and will not work well, as I am now.I already mentioned the scope, but is my logic that flawed on the IGBT's and pulse width? Shouldn't I see heat? Especially with the 5+ 5min runtimes I had in the start with no heat and no zeners? I don't think it will hurt to throw the Arduino on there, but this has and can be done with fets. And I have a ton. Shouldn't that be a good enough reason to just use them for testing?
The schematic you show in your very first post, for your H-bridge and Guangyan's full schematic, both are for DRSSTCs. In your H-bridge schematic C1 is the primary tank capacitor.Im am also confused o. You DRSSTC statement. I have done about 6months of research, maybe what I read was all fake but if memory from research serves correctly. Im not even making a DRSSTC that would require a resonant tank capacitor in series with the primary coil.
I got My IGBT's for about $5 each, Then the other parts are new, just leftover from other projects...So I do apologize I can't get u a waveform based on Equipment your used to but I've seen these made with less and I'm not going g to spend $500 on a 20$ project. I had every part new inboxes other than the IGBT's.
Okay well back to my original point, I have a ton of fets, Cant I get to a point of knowing it works before frying something I'm limited In. You also said for DRSSTC(I thought this was a SSTC since the guy making is called it one https://www.loneoceans.com/labs/sstc2/ He mentions the cap placed in series with his primary was a DC blocking cap nothing about a tank cap or adding power. As well this guy says a couple times that the DR difference is a cap is placed in parallel with the primary not in series so this was my confusion. I read on a different page he said series. I guess typo?) So If there so horrible for DRSSTC can I remove the 4.7uf cap to make it a SSTC and test with the fets?As for DRSSTCs being done with MOSFETs, anyone who has actually built a DR will tell you that they are a poor choice and will not work well, as I am now.
Yes, when scoped, if one pin is grounded I get no reading on the other. If one is floating I get a decently clean wave on the other, isnt that a wound antenna tho?Also I cannot for the life of me get that guys feedback transformer to work. Its a simple 50turns with secondary ground ran through the toroid ring. I tried flipping connections and the way the wire went through thinking phase was off. but I cannot get a signal when one transformer leg is grounded. If I leave one end open and other as feedback to inverter it works but isnt that just a wound antenna then? I tried a number of different cores and just cant get it. its like when I ground one of the two pins I just am pulling the inverter to ground so then not pulsing at all ...WTF??? any thoughts on that?
This was only in the videos, this was NC when trying mains, the music I thought acts as the interupter. If I do this down the road, do I need to have a modulating input as well as the music? Wont that make a constant(Buzz) frequency behind the music? or maybe have it transfer from music to modulation, so when the music isnt playing it swaps to the arduino, so it isnt in CW mode?1) You are running this in CW ("Continuous Wave") mode, which means no interrupter. That is an excellent way to destroy transistors (whether MOSFETs or IGBTs).
Could you explain this to me? So is it the value that changes it to a DR?2) I did not look closely enough at the series capacitor value. 4.7uF is indeed for DC-blocking, and not for resonance (this is a bit embarrassing that I did not look closely enough at the value, so my apologies there).
They are IXTQ50N25, 250v, 50a, 400W, switching times 14-24ns3) Being a basic SSTC rather than DRSSTC, the currents will be lower so you may be able to get away with FETs after all, provided they are fast-switching and are rated for a high-enough voltage/current.
Yes, if you leave one end floating then it becomes a basic antenna and not a current transformer. I am curious how you built your transformer. What are you using for a core? If I had to guess I would say you're using the wrong core material. Powdered iron toroid cores, for example, are extremely common and used in all sorts of applications (power supplies, especially) but are TERRIBLE at high frequencies. They are most often used for chokes, rather than transformers. For a CT you really need something with an extremely high permeability (>10,000). The cores I use can be found on Digikey (https://www.digikey.com/products/en?keywords=495-3868-ND). I would expect this is the most likely reason for failure.Yes, when scoped, if one pin is grounded I get no reading on the other. If one is floating I get a decently clean wave on the other, isnt that a wound antenna tho?
Just because you're playing music through it does not mean it's acting as an interrupter. That depends completely on your driver circuitry, but it looks CW to me. Usually when someone wants to play music through a non-CW coil, they need to modulate the interrupter to play each note one-by-one. Your'e just overlaying the music over the CW frequency, ~170kHz, which humans can't hear.This was only in the videos, this was NC when trying mains, the music I thought acts as the interupter. If I do this down the road, do I need to have a modulating input as well as the music? Wont that make a constant(Buzz) frequency behind the music? or maybe have it transfer from music to modulation, so when the music isnt playing it swaps to the arduino, so it isnt in CW mode?
Once again, SSTCs will be different from DRSSTCs in the sense that the MOSFETs will not see as much current, so they will not heat up nearly as much as IGBTs in a DRSSTC would. The lower duty cycle suggestion was more for DRSSTCs, which have much higher power transfer from the primary to the secondary, thus causing the primary to draw much more current. SSTCs do not have that second resonant circuit, though, so they draw much less current (and for that reason have a less impressive output).Right now I have the multi-vibrator @ 350hz 50% duty. I will switch to the arduino and shorten my on time as you stated. When running in this video I could run for 20mins straight and mosfets barley got warm, on 42watts with no modulation or music I could probably run it for an hour without heatsinks.(lol not saying do this I'm just stating it ran very cool, it did not seem like I had any crossover switching causing fets to heat up at all)
Sure. In a dual resonant solid state Tesla coil the series capacitor is designed to resonate with the primary coil at the same frequency at which the secondary coil and topload resonate. This creates two tuned circuits which allows much more efficient energy transfer from the primary circuit to the secondary circuit.Could you explain this to me? So is it the value that changes it to a DR?
Most definitely!! lol cuz ur right about a DRSSTC and my research. I have poked around in that area although I was reading how complex they are. So I was trying to stay away....LOL.... I tried to read all I could find about SSTC's. But awesome that makes complete since to me thanks for that.Transitioning to a DRSSTC versus a SSTC would require other changes as well, though, so just stick with the SSTC for now.
I havent explained my driver setup fully but I thought I was modulating with music. I am simply amplifying a headphone output to 12V then using a inverter to clip every note, Therefor if I have a 1khz audio tone it is now a 12v square pulse repeating at 1khz, So I though I was converting my audio to pulse repetition frequency modulation. I thought it is modulating since I am not overlaying this on my resonance I am enabling and disabling my gate driver. If you look in the ACDC video the scope waveform is the square audio wave going to the enable pins. Back to a 1khz tone, I thought Im pulsing my 170khz resonate freq at 1khz. At least thats what I thought. I read if you modulate at 200hz you get a 200hz tone, so me turning my driver on and off at the frequency the music is at I thought would be the same. Its the same input I use to actually modulate with my miltivib. Am I way off here? If I am modulating maybe u got thrown off cuz I had the phase of Music input always high. so the arc was constant with no music. That was also just for testing I know thats suppose to be low so it only lights up when a musical tone is playing, therefor being off when muted. So I was practically turning it OFF at the music freq not ON in those videos.Just because you're playing music through it does not mean it's acting as an interrupter.
So in your SSTC opinion would I be okay to test at 50% duty since its a lot less current then a DR? and possibly watch heat and change accordingly. Or is 50% on time on a SSTC way to high also?Once again, SSTCs will be different from DRSSTCs in the sense that the MOSFETs will not see as much current, so they will not heat up nearly as much as IGBTs in a DRSSTC would. The lower duty cycle suggestion was more for DRSSTCs, which have much higher power transfer from the primary to the secondary, thus causing the primary to draw much more current. SSTCs do not have that second resonant circuit, though, so they draw much less current (and for that reason have a less impressive output).
Ah, I see. You still haven't provided a schematic for the rest of your circuit (unless it is identical to Guangyan's) so I don't know where you are applying the signal. It appears you are interrupting the coil, but at a very high frequency. Since you're not just playing one note at a time with the music you're feeding into it you are actually getting multiple audio signals at once, so when overlaid on one another your interrupter frequency is much, much higher than any one note. Also, your high duty cycle would help explain the CW-looking arc.I havent explained my driver setup fully but I thought I was modulating with music. I am simply amplifying a headphone output to 12V then using a inverter to clip every note, Therefor if I have a 1khz audio tone it is now a 12v square pulse repeating at 1khz, So I though I was converting my audio to pulse repetition frequency modulation. I thought it is modulating since I am not overlaying this on my resonance I am enabling and disabling my gate driver. If you look in the ACDC video the scope waveform is the square audio wave going to the enable pins. Back to a 1khz tone, I thought Im pulsing my 170khz resonate freq at 1khz. At least thats what I thought. I read if you modulate at 200hz you get a 200hz tone, so me turning my driver on and off at the frequency the music is at I thought would be the same. Its the same input I use to actually modulate with my miltivib. Am I way off here? If I am modulating maybe u got thrown off cuz I had the phase of Music input always high. so the arc was constant with no music. That was also just for testing I know thats suppose to be low so it only lights up when a musical tone is playing, therefor being off when muted. So I was practically turning it OFF at the music freq not ON in those videos.
This is really going to depend on how much current your H-bridge sees. If you keep blowing MOSFETs, use a lower duty cycle. It will vary from coil to coil.So in your SSTC opinion would I be okay to test at 50% duty since its a lot less current then a DR? and possibly watch heat and change accordingly. Or is 50% on time on a SSTC way to high also?
I never recommend using salvaged transformers for Tesla coil CTs because it is very difficult to know what they are made of. Unless you have a lot of cores and want to do a lot of trial and error, you'd probably be much better off spending the $3 and buying a brand new one with known specs.On the core of the feedback transformer, I tried 4 different ones Im using toroids. I guess they all may not be ferrite. Ill poke around in my crap for some others. I usually try to use audio ones, I have had 100% luck with those but there a little big for this.
This sort of Tesla coil is self-tuning, meaning the feedback directly controls the switching of the primary coil at whatever frequency the secondary is resonating at. I'm not exactly sure why it's not working for you above four turns. What exactly happens when you try? Without probing different parts of the circuit with a decent oscilloscope, in-depth troubleshooting is next to impossible. What current is your supply capable of providing? Try running the coil at a fixed 400Hz frequency with, say, a 25% duty cycle. No audio modulation. Then try increasing the primary turns (while keeping the interrupter at 400Hz) and see if it works. Maybe even try a lower frequency than that. Just playing around here....Hey I wanted to Ask:
So in this guys circuit/setup he uses 34 gauge, 980 turns, on 3.5" abs, res. is in the 200khz. So this is pretty close to mine but he was at 7 turns on his primary with 14AWG wire, Same as im using. He upped his width to 4" to reduce coupling and dropped to 6 turns.
Now why cant I get mine to work above 4 turns? I was thinking because my resonance was lower but when I tried my higher 600KHZ secondary on this it wanted even less turn on the primary. so Im lost...
The impedance (resistance + reactance) of the primary coil is mainly what determines the current draw in this circuit, since it is in an H-bridge. It is very difficult to calculate because there are a number of factors that come into play. Let me think about it a bit and I'll get back to you.Also what dedicates the amount of current this will pull? Is it the inductance of the secondary? or reactance? I wanted to know cuz if his was at 6 turns I was hoping my 2.75 turns isnt ganna pull twice the current his did. Is there a quick calculation I can do to estimate my current? Nothing super accurate, just in the ball park. When I read into this it said you'll need the impedance of the hole circuit plus inductance and capacitance.
It just stops outputting a spark, So it gets stronger and stronger as i get closer to 2.75 turns but as I go further and further it gets weaker and weaker, then above 4 turns the arc goes out. I have tried all sorts of frequencys on modulation without audio 5hz-5khz including CW and it still goes out.I'm not exactly sure why it's not working for you above four turns. What exactly happens when you try?
These have a prop 60ns, trans 40ns, 74HC14 have prop 20ns trans 6ns, Now yes its slower but ur telling me 60ns cant switch 170khz? accurately? It Ran my 600khz secondary just fine. I can post a scope of that out put, looks great to me.1) You should be using 74HC series logic. CD4000 series is probably not fast enough
Im running 12v because Im not using 5v logic... That was part of my design I liked 12v. Are you saying I cant do that, if so why? I understand its different from everyone else but ur saying u cant run the driver at 12v?2) The feedback section must be referenced to +5V, not +12V (important when you use 74HC logic)
That was a mistake, Sorry those 2 are not there, there is one 151 there, so 150pf...3) C1 & C6 are a huge mistake. If you look at Guangyan's schematic he uses a 0.1nF capacitor (that's 100pF). At 170kHz the reactance of the capacitor is 1/(2*pi*170kHz*0.1nF) = 9.36k ohms. You, on the other hand, are using two 10nF capacitors in parallel which equals 20nF. The reactance of your equivalent capacitor is 1/(2*pi*170kHz*20nF) = 46.8 ohms. You're creating a low-impedance path to ground at your resonant frequency, which pretty much guarantees the driver will not receive a sufficient feedback signal.
Since Im driving at 12v I did 12 primary 12 on secondarys, I get 10.7-11.2v out, I was thinking of dropping a turn or two on primary to up to 13v ish.4) How are your GDTs wired? What are the turns ratios? I ask because your driver is only driving them with 12V, and the MOSFETs may need a higher voltage than that in order to turn on fast enough for your purposes.
Right now my driver is powered from a PSU 12v rail. I did stick a 100uf cap there yesterday but no change but i left it.5) Where is your reservoir capacitor between VCC and GND of your driver chip?
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