Author Topic: DRSSTC fails to oscillate  (Read 2886 times)

Offline npmarshall

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DRSSTC fails to oscillate
« on: March 20, 2023, 02:21:05 PM »
Hello all,

This is my first post to this forum. I have lurked here quite a lot in the past, but never had the need to ask a question. I have built simple SSTCs in the past, and now I am building my first DRSSTC with the intention of demonstrating it at an upcoming physics festival in a couple of weeks. The goal for this coil is to have a compact design with reliable performance and musical capabilities. I have been struggling for the last week or so trying to get the coil to oscillate from its own feedback. Below are some specs and pictures of the setup. Please forgive the somewhat messy wiring at the moment, I plan to tidy everything up and shorten leads as much as possible once I achieve oscillation.

Specifications:
- 12" x 2.5" secondary, ~1000 turns
- 3" x 9" aluminum toroid
- resonant frequency of secondary measured at ~460 kHz
- spiral primary, dimensions approx. 1.75" to 3.5" radius with 5.75 turns of 8 AWG solid wire
-  MMC consists of two series 68 nF arcotronics C.4C MKP capacitors for a total capacitance of 34 nF
- resonant frequency of primary measured at ~430 kHz with primary tapped at 4.75 turns
- primary feedback via cascaded toroids with a ratio of ~300:1
- full bridge of FGA60N65SMD IGBTs,  bridge PCB design from profdc9 PCB back on github
- 340 VDC bus from a voltage doubler with two 1900 uF bus capacitors and MUR460 rectifiers
- pulse width variable from 10-150 us with homebuilt Arduino-based fiber interrupter
- UD2.7c driver design from loneoceans


The coil in all its glory


Primary coil


Full bridge, DC bus, and secondary 50:1 current transformer for scoping


MMC and two 300:1 current transformers, one for feedback and one for scoping


1:1 GDT, 11 turns


I have tried reversing phasing of the current transformer and primary many times to no avail. I have also tried running it from secondary feedback and an antenna but haven't had any luck. I have run the bus voltage all the way up to >200 VDC but I just can't get it to oscillate on its own. Here are some scope shots of (unloaded) current transformers on the primary and secondary at 80 VDC:


Blue trace is primary CT, yellow is secondary


Same thing as above but zoomed in on the larger pulse envelope


It appears there are a few envelopes of oscillation, but this is likely just from strange gate drive shapes due to the GDT saturating. There is a loud audible buzz from the GDT as it saturates. I have no issue getting the driver to oscillate with external feedback fed into the UD2.7c from a signal generator. Here are some scope shots:


unloaded driver output with no GDT attached, 430 kHz external feedback


Running the coil with external 430 kHz feedback. Blue trace is primary CT, yellow is secondary. Strangely, the primary seems to oscillate at twice what I would expect from the 430 kHz feedback. What is going on here? Am I misunderstanding something or does this indicate some issue? With external feedback the coil is able to illuminate a small neon bulb and make small sparks to metal objects that are brought near, but it is quite weak even at high bus voltage.

I appreciate any feedback and suggestions! Please let me know if more information is needed.

- Nathan
« Last Edit: March 20, 2023, 02:24:11 PM by npmarshall »

Offline davekni

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Re: DRSSTC fails to oscillate
« Reply #1 on: March 21, 2023, 01:31:51 AM »
Quote
Here are some scope shots of (unloaded) current transformers on the primary and secondary at 80 VDC:
I'd recommend loading all CTs with burden resistors for all testing.  No open CTs.  Any unloaded CT adds inductance and perhaps resonances due to CT wire capacitance, so will confuse measurements.

Quote
Strangely, the primary seems to oscillate at twice what I would expect from the 430 kHz feedback. What is going on here?
How was primary resonant frequency measured?  If there was an open CT during measurement, that could be the issue.  At low amplitude, open CT adds inductance and makes frequency look good.  At higher amplitude, CT saturates, so frequency increases.  Would be good to enter coil geometry into JavaTC to estimate frequencies and coupling factor etc.  That will be close, so point out any issues in measurement.

Good luck with debug!
David Knierim

Offline npmarshall

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Re: DRSSTC fails to oscillate
« Reply #2 on: March 21, 2023, 01:47:59 AM »
Dave,

Okay I will retry all measurements with burden resistance. The geometries were all pre-designed with JavaTC before construction and the measured values come out very close to the predictions. Coupling factor is about 0.15. I measured the primary frequency before the bridge was connected by placing the MMC in parallel with the secondary and then connecting my signal generator with a 10k resistor on the output lead across the MMC. The waveform was scoped across the MMC to find the resonance.

Offline Rafft

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Re: DRSSTC fails to oscillate
« Reply #3 on: March 21, 2023, 02:58:29 AM »
I dont see any GROUND wire (?) secodary coil

For untested builds. Its always safer to test at lower voltages. Variac would be nice. Even at 60vbus, DRSSTC can attain a breakout. Never give it full mains voltage just because it fails.
SGTC / SSTC / DR-SSTC / QCW

Offline npmarshall

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Re: DRSSTC fails to oscillate
« Reply #4 on: March 21, 2023, 03:16:44 AM »
The ground wire is visible in the second photo passing through the secondary CT. I am already using a variac on the bus input. The testing has all been done well below full bus voltage.
« Last Edit: March 21, 2023, 03:18:53 AM by npmarshall »

Offline davekni

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Re: DRSSTC fails to oscillate
« Reply #5 on: March 21, 2023, 03:59:13 AM »
Quote
Okay I will retry all measurements with burden resistance.
Sounds like primary resonance test was w/o CTs and matches JavaTC, so no need to repeat that.
Coupled system of primary and secondary will have two resonant frequencies.  DRSSTCs typically run at the lower frequency (lower pole).  About 7% low due to 15% coupling if two frequencies were initially identical and if I'm running math correctly.  LTSpice or other analog simulator is a good way to check expected frequencies for coupled resonant circuits.

One other less-likely possibility is an unwanted resonance of on-board bypass capacitors (snubbers) and lead inductance to bulk caps.  I've seen two cases here on the forum where that resonance happened to be at 2x operating frequency.
David Knierim

Offline npmarshall

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Re: DRSSTC fails to oscillate
« Reply #6 on: March 21, 2023, 01:49:09 PM »
Quote
Sounds like primary resonance test was w/o CTs and matches JavaTC, so no need to repeat that.
Correct, I think the primary resonance measurement is reliable.
Quote
One other less-likely possibility is an unwanted resonance of on-board bypass capacitors (snubbers) and lead inductance to bulk caps.
Very interesting, an unexpected resonance is something I need to investigate. It would explain why even when running with external feedback the output is really poor since the primary is resonating way above the resonant frequency of the secondary at about twice the drive frequency. I actually have left the RC snubbers unpopulated on my bridge PCB and only have the DC link caps and TVS diodes installed for transient control. Does this rule out that possibility then?

I currently have no MMC bleed resistance installed and I’m considering trying to add that to see if it changes anything.

Offline npmarshall

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Re: DRSSTC fails to oscillate
« Reply #7 on: March 22, 2023, 02:19:31 AM »
Good news, I've got the coil oscillating on its own feedback now! Not sure exactly what changed, but I went back over my connections and then tried the 50:1 current transformer for feedback into the UD2.7 and something seems to have helped. Oscillation is unsteady until I get over about 100 volts on the bus. See the attached scope shot where I am scoping one of my 300:1 transformers with a 51 ohm burden resistor. Current is low, about 5 amps at the peak if I've calculated that correctly for the ~0.8V peaks. Still work to be done but this is much easier to work with! The resonant frequency looks slightly higher than expected now at around 520 kHz. So the first order of business is to correct that. I may need to adjust my MMC value.

Please give any suggestions you might have for what else I need to do in order to get the primary current up!

« Last Edit: March 22, 2023, 02:38:36 AM by npmarshall »

Offline davekni

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Re: DRSSTC fails to oscillate
« Reply #8 on: March 22, 2023, 02:40:09 AM »
Quote
I actually have left the RC snubbers unpopulated on my bridge PCB and only have the DC link caps and TVS diodes installed for transient control. Does this rule out that possibility then?
Does not rule out resonance of wire to bulk caps.  I was actually referring to the DC link caps on the board.  I'm used to calling them that or bypass caps.  On this forum I see many people referring to the DC link caps as "snubber" caps.  So I used that term in case you had a similar meaning.  I would much prefer that snubber caps always meant caps in series with resistors used to reduce spikes on AC nodes (switching nodes), and never for caps across nominally-DC voltage.

Quote
I currently have no MMC bleed resistance installed and I’m considering trying to add that to see if it changes anything.
Bleed resistors across MMC are mostly to balance voltage between MMC stages and to bleed off any remaining charge after running.
As Mads suggests, a resistor across H-bridge output can be helpful for startup.  Lower voltage there than across MMC, so lower resistance can be used.  Helps make sure initial output is 0V so either polarity of first half-cycle generates enough current through feedback to trigger next half-cycle etc.

Quote
Oscillation seems unsteady till I get over about 100 volts on the bus. See the attached scope shot where I am scoping one of my 300:1 transformers with a 51 ohm burden resistor. Current seems low, about 5 amps at the peak if I've calculated that correctly for the ~0.8V peaks.
Yes, something is still quite problematic.  Might be easier to diagnose issue with signal-generator into UD2.7 and low bus voltage.  Clean waveforms are easier to figure out.
David Knierim

Offline npmarshall

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Re: DRSSTC fails to oscillate
« Reply #9 on: March 22, 2023, 03:01:33 AM »
Quote
Might be easier to diagnose issue with signal-generator into UD2.7 and low bus voltage.  Clean waveforms are easier to figure out.
Agreed, I will switch back to external feedback and try that again next. What would you suggest I do to test or fix the DC link resonance issue if that is indeed the case? Any other common issues I should look for? I’m a DRSSTC newbie so I’d like to lean on any experience that I can.
« Last Edit: March 22, 2023, 03:03:07 AM by npmarshall »

Offline davekni

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Re: DRSSTC fails to oscillate
« Reply #10 on: March 22, 2023, 04:31:52 AM »
Quote
What would you suggest I do to test or fix the DC link resonance issue if that is indeed the case? Any other common issues I should look for?
To see if this is an issue, scope Vbus at H-bridge (voltage across link capacitors) while sweeping frequency generator input around desired coil operating frequency.  See if there is a frequency where Vbus has a large AC swing at twice frequency of generator input.
For mitigating, I presume that increasing DC link capacitance isn't easy.  Another option is to reduce wire inductance from bulk caps, such as by making leads shorter or by pairing leads together (minimize loop area) and/or by using multiple pairs of wire.

One more thought on possible issue when using feedback:  Saw this on one other high-frequency coil as yours.  Most people run initial tests with UD2.7 phase-lead jumper set for no phase lead.  It is possible to have enough delay through UD2.7, GDT, and IGBTs to add up to over 90 degrees at high frequency.  Such delay combined with reversed feedback polarity can lead to oscillation at a frequency above resonance.  (Never run UD2.7 with phase jumper removed.  Always in one position or the other.  Can burn resistors or comparitor if open.)
Thus I'd suggest a test when generator input to UD2.7:  (Remember to add burden resistor across CT output when not connected to UD2.7 feedback input.)  Tune generator to resonance (max current) at low Vbus.  Then scope generator output (UD2.7 input), UD2.7 output (GDT input), and H-bridge output voltage, all using a common trigger such as generator output.  See what delay is through your system.  Convert that delay to phase.  Then calculate phase-lead inductance to achieve that shift or a bit more when added to UD2.7's internal 51-ohm burden resistor.  When trying closed-loop operation again, use that inductance as a starting point rather than disabling phase-lead.
David Knierim

Offline Rafft

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Re: DRSSTC fails to oscillate
« Reply #11 on: March 22, 2023, 06:05:18 AM »
Some more:

Ferrite material for gdt/ft/ct. Also away from resonator(pri/sec)

Try 10:10:1 for feedback

Maybe resonance/MMC is not suitable for DR use. Try CBB81 pp


SGTC / SSTC / DR-SSTC / QCW

Offline npmarshall

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Re: DRSSTC fails to oscillate
« Reply #12 on: March 22, 2023, 05:07:39 PM »
The ferrite cores are Fair-Rite material 78 for the GDT and 300:1 CTs, material 77 for the 50:1 CT. These should be good for DRSSTC use. I plan to order some CDE 942 MMC caps, larger link caps, and I’ll also see if I can get some CBB81 caps to have on hand as well. While waiting for those to ship I’ll work on minimizing lead inductance coming out of the bridge and try to play with phase lead as Dave suggested. Hopefully I can get it working by April 1st when I’d like to demo it!

Thanks for the suggestions!

Offline npmarshall

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Re: DRSSTC fails to oscillate
« Reply #13 on: March 23, 2023, 04:08:07 PM »
Some exciting new results! I worked on minimizing primary lead inductance by pairing the wires more closely together as they leave the bridge, and then played around with CT phasing and primary phasing. Now the coil starts to oscillate at just 30 VDC input with a 300:1 CT. The current is much higher. Phase lead seems to play a very important role. With the inductor bypassed on the UD2.7, the oscillation looks pretty bad and it takes a slightly higher voltage to start oscillation. also the resonant frequency seems quite a bit lower than what I would expect. With the jumper switched to add inductance, the waveform cleans up and the resonant frequency is closer to the theoretical value based on the tap point I'm using. The power sharing of the IGBTs is very bad. One of the high-side IGBTs gets very hot at higher voltage and frequency while the others remain barely warm to the touch. Could this IGBT be bad or does this indicate some other issue? Still no breakout but that is likely do to the system being imperfectly tuned.

FGA60N65SMDs are seeming a bit scarce from my typical suppliers at the moment… can anyone suggest a decent alternative IGBT? I’d like to have a few more transistors on hand.

Let me know what you think I need to try next!


Primary current at 40 VDC scoped with a 50:1 CT and a 51 ohm burden resistor, no phase lead


Same as above but with phase lead enabled. Notice the current is actually higher, the y-scale has changed here on the plot


Zooming in on the waveform with no phase lead. Notice the strange shape and low resonant frequency


Zooming in on the waveform with phase lead. Notice the shape is improved and the resonant frequency has changed. The bus voltage was lower for this scope shot but I forgot to measure it. Probably around 20 VDC.
« Last Edit: March 24, 2023, 12:48:07 AM by npmarshall »

Offline davekni

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Re: DRSSTC fails to oscillate
« Reply #14 on: March 24, 2023, 03:00:38 AM »
Quote
With the inductor bypassed on the UD2.7, the oscillation looks pretty bad and it takes a slightly higher voltage to start oscillation. also the resonant frequency seems quite a bit lower than what I would expect.
That is expected behavior.  Delay through UD2.7 and H-bridge slows down oscillation.  Unless feedback phase is inverted, in which case it can oscillate at high frequency instead.

Quote
The power sharing of the IGBTs is very bad. One of the high-side IGBTs gets very hot at higher voltage and frequency while the others remain barely warm to the touch. Could this IGBT be bad or does this indicate some other issue?
Clearly some issue that needs fixing.  One possibility is that the opposite IGBT of that half-bridge is shorted or conducting extra current.  Recommended test:  Power H-bridge only, perhaps 40V, with UD2.7 disabled or off.  Check that both H-bridge outputs are floating, can easily be pulled high or low with perhaps 1k resistor.  Including checking one output high and other low and visa-versa.  If that shows no issue, next test:  0V to H-bridge and UD2.7 running from signal generator.  Scope all four Vge waveforms.  Verify waveform shape and that high and low sides of each half-bridge are inverted phase, not same phase.
Edit:  Run both tests even if first shows bad IGBT(s).  Incorrect Vge phasing (reversed GDT output wire pair) or other Vge issues are most likely cause of any IGBT failures.

Quote
FGA60N65SMDs are seeming a bit scarce from my typical suppliers at the moment… can anyone suggest a decent alternative IGBT? I’d like to have a few more transistors on hand.
fgh75t65 is an option.  I recently purchased some of the 4-lead versions, using them initially in my new QCW experiment (not posted yet) at similar frequency to your coil.  Don't have a lot of experience yet.  The part I've used many of is no longer available most places, STGW60H65DRF.

Quote
Let me know what you think I need to try next!
There is an issue shown in current waveforms.  Current should not end suddenly at end of UD2.7 enable as your waveforms show.  Instead should ring down.  This may be related to hot IGBT issue above, or might be a separate issue such as bad MMC cap.

Good luck with debug!  BTW, I finished my DRSSTC 1.5 weeks before its scheduled showing at our local Maker Faire in 2019.  I'd already told them it might not be ready in time back when first signing up several months earlier.
« Last Edit: March 24, 2023, 04:05:13 AM by davekni »
David Knierim

Offline npmarshall

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Re: DRSSTC fails to oscillate
« Reply #15 on: March 24, 2023, 05:19:38 PM »
Dave, thank you for making me check my GDT phasing! Even though I had the correct phasing of the leads marked, I had made an error when screwing them in to the terminals! With that corrected, I achieved first light this morning. The coil oscillates now with less than 10 volts on the bus. The same transistor still gets a lot hotter than the others. I may have cooked it a few too many times in testing and need to replace it. It was blazing hot when I first noticed the problem. Still need to work on the tuning a bit, but the streamers are already quite large at 1Hz repetition rate and < 100us pulse widths.

Thank you so much for the help thus far. I will continue to update on my progress!


Primary current, 50:1 CT with 51 ohm burden resistor, 12 VDC on the bus


 The breakout at 1Hz, perhaps 100 VDC on the bus, and ~100us pulse width!



Offline davekni

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Re: DRSSTC fails to oscillate
« Reply #16 on: March 24, 2023, 07:17:47 PM »
Quote
With that corrected, I achieved first light this morning.
Congratulations on first light!

Quote
The same transistor still gets a lot hotter than the others. I may have cooked it a few too many times in testing and need to replace it.
Even though you fixed the biggest issue, it might be wise to finish the tests from my last post.  Chances are that one IGBT has high leakage current (partial short).  If so, would be better to replace it now rather than waiting for it to completely fail and damage the other IGBT in that half-bridge.  Vge issues are less likely a result from previous over-heating.  Still may be worth scoping, especially if leakage test does not show any problems.

Quote
Primary current, 50:1 CT with 51 ohm burden resistor, 12 VDC on the bus
Yes, much more an expected waveform.  The small amplitude modulation shows dual-resonance.  If primary and secondary frequencies were identical, modulation would be large.  However, primary should be tuned below secondary, to match secondary's reducing frequency as arc load increases capacitance.
« Last Edit: March 24, 2023, 07:20:58 PM by davekni »
David Knierim

Offline npmarshall

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Re: DRSSTC fails to oscillate
« Reply #17 on: March 26, 2023, 01:32:56 AM »
The issue appears to have been a partially shorted IGBT. Thanks to the fact that a Mouser location is very close to me, I can get parts from them in 1-2 days with standard shipping. So, I went ahead and ordered some FGH75T65 IGBTs and built another full bridge since I had all the other components on hand. I can fix the original one and have it as a backup if needed. The coil performs quite well! Now I'm using two series 47nF CDE942C capacitors as an MMC and this gives a resonant frequency of 390kHz with 5.5 turns on my primary. The ring down of my secondary has a frequency of 420 kHz, so I'm slightly below resonance for good streamer growth. I'll experiment with different tap locations, but I'm already really pleased with the performance!


140 VDC on the bus, 1 Hz repetition rate, and maybe 20us on-time. The breakout length is just as impressive with my minimum on-time of 10us. The IGBTs are barely warm to the touch after running like this. Now for some good heatsinks, phase lead tuning, and then time to try MIDI music!

Can't thank you enough for your help on this. It should be an exciting demo for hundreds of people next weekend! If anyone is close to College Station, Texas, come stop by and see me at the Texas A&M Physics and Engineering Festival!

- Nathan
« Last Edit: March 26, 2023, 03:07:44 AM by npmarshall »

Offline davekni

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Re: DRSSTC fails to oscillate
« Reply #18 on: March 26, 2023, 03:00:51 AM »
Quote
Can't thank you enough for your help on this. It should be an exciting demo for hundreds of people next weekend! If anyone is close to College Station, Texas, come stop by and see me at the Texas A&M Physics and Engineering Festival!
You are certainly welcome!  I'm always thrilled when the end result is success.  Hope your demo goes well.
David Knierim

Offline npmarshall

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Re: DRSSTC fails to oscillate
« Reply #19 on: March 28, 2023, 06:04:10 PM »
I have been playing with the coil to optimize it for the big day. I have a couple questions that have come up while experimenting with it. Firstly, when I try to run at higher repetition rates above 20Hz with higher bus voltage (~170VDC), the 10A fuse on my variac blows. Is this normal considering it is not a slow blow fuse? Should I be using a slow blow fuse to prevent this?

Also, when I tried to push the bus voltage over 200VDC, my single 33nF CDE942C MMC failed. Perhaps this is to be expected for a single MMC cap running on a full bridge. Does this seem reasonable? I think I will be conservative and keep the voltage lower for my demonstration if this is the case. Should I consider running this coil in a half bridge configuration instead? Maybe that would run a bit better due to lower voltage and higher current paired with my relatively low inductance primary. I can easily switch to using half of my full bridge PCB.
« Last Edit: March 28, 2023, 07:40:53 PM by npmarshall »

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Re: DRSSTC fails to oscillate
« Reply #19 on: March 28, 2023, 06:04:10 PM »

 


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post Ignitron trigger drive ideas?
[Capacitor Banks]
klugesmith
April 15, 2024, 09:06:42 PM
post Re: First DRSSTC SKM100
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
April 15, 2024, 08:46:32 PM
post Re: Game changing tesla coil secondary winding suggestions
[General Chat]
Benbmw
April 15, 2024, 08:38:39 PM
post Re: Game changing tesla coil secondary winding suggestions
[General Chat]
sky-guided
April 15, 2024, 08:23:40 PM
post How to get a GE Yokogawa AB40 Sync Scope to rotate without a powerplant.
[Laboratories, Equipment and Tools]
Bobakman
April 15, 2024, 06:43:23 PM
post Re: First DRSSTC SKM100
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
April 15, 2024, 06:29:10 AM
post Re: Small-ish 3D printed SGTC via cheap ZVS flyback build, humbly asking a couple ?s
[Spark Gap Tesla Coils (SGTC)]
Michelle_
April 15, 2024, 05:21:53 AM
post Re: Small-ish 3D printed SGTC via cheap ZVS flyback build, humbly asking a couple ?s
[Spark Gap Tesla Coils (SGTC)]
Michelle_
April 15, 2024, 05:15:33 AM
post Re: First DRSSTC SKM100
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
April 15, 2024, 04:07:54 AM
post Re: Small-ish 3D printed SGTC via cheap ZVS flyback build, humbly asking a couple ?s
[Spark Gap Tesla Coils (SGTC)]
davekni
April 15, 2024, 03:49:03 AM
post Re: Small-ish 3D printed SGTC via cheap ZVS flyback build, humbly asking a couple ?s
[Spark Gap Tesla Coils (SGTC)]
alan sailer
April 14, 2024, 09:46:30 PM
post Small-ish 3D printed SGTC via cheap ZVS flyback build, humbly asking a couple ?s
[Spark Gap Tesla Coils (SGTC)]
Michelle_
April 14, 2024, 07:31:00 PM
post Re: First DRSSTC SKM100
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Saattvik24
April 14, 2024, 02:26:19 PM
post Re: mg75q2ys40 IGBT
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
April 14, 2024, 07:20:54 AM
post Re: IKY150N65EH7, is it good for DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
April 14, 2024, 07:18:20 AM
post Re: Game changing tesla coil secondary winding suggestions
[General Chat]
Michelle_
April 13, 2024, 06:46:40 AM
post Re: Game changing tesla coil secondary winding suggestions
[General Chat]
Michelle_
April 13, 2024, 04:18:42 AM
post Re: Upper and Lower Explosive Limits on Confined Flammable Vapors at -79 C.
[General Chat]
alan sailer
April 13, 2024, 03:24:20 AM
post Re: Game changing tesla coil secondary winding suggestions
[General Chat]
alan sailer
April 13, 2024, 03:20:46 AM
post Game changing tesla coil secondary winding suggestions
[General Chat]
Michelle_
April 13, 2024, 03:13:22 AM
post Re: Capacitor Blowout
[Sell / Buy / Trade]
lbattraw
April 12, 2024, 09:14:58 PM
post mg75q2ys40 IGBT
[Dual Resonant Solid State Tesla coils (DRSSTC)]
thedark
April 12, 2024, 08:40:18 PM
post Re: UD 2.7 OCD LED stays on, no output during inital test
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
April 12, 2024, 07:20:30 PM
post Re: Mosfet Buffer Stage Questions
[Beginners]
davekni
April 12, 2024, 07:12:43 PM
post IKY150N65EH7, is it good for DRSSTC
[Dual Resonant Solid State Tesla coils (DRSSTC)]
ethanwu0131
April 12, 2024, 04:47:33 PM
post Re: UD 2.7 OCD LED stays on, no output during inital test
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Admiral Aaron Ravensdale
April 12, 2024, 11:43:36 AM
post Mosfet Buffer Stage Questions
[Beginners]
Egg
April 12, 2024, 12:49:02 AM
post Re: UD 2.7 OCD LED stays on, no output during inital test
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
April 12, 2024, 12:41:16 AM
post Re: Plasma Torid - Class E Self Resonant Dual/Stereo - Plasma Torid Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
April 12, 2024, 12:22:41 AM
post Re: Capacitor Blowout
[Sell / Buy / Trade]
Michelle_
April 11, 2024, 10:45:53 PM
post Re: UD 2.7 OCD LED stays on, no output during inital test
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Admiral Aaron Ravensdale
April 11, 2024, 07:39:30 PM
post Re: UD 2.7 OCD LED stays on, no output during inital test
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
April 11, 2024, 07:24:52 PM
post Re: Tesla coil safety questions, risk analysis quantified
[Beginners]
sky-guided
April 11, 2024, 06:09:30 PM
post UD 2.7 OCD LED stays on, no output during inital test
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Admiral Aaron Ravensdale
April 11, 2024, 12:55:16 PM
post Re: Plasma Torid - Class E Self Resonant Dual/Stereo - Plasma Torid Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
April 11, 2024, 03:40:00 AM
post Re: Plasma Torid - Class E Self Resonant Dual/Stereo - Plasma Torid Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
sky-guided
April 11, 2024, 03:05:07 AM
post Re: Tesla coil safety questions, risk analysis quantified
[Beginners]
Michelle_
April 11, 2024, 02:57:33 AM
post Re: Tesla coil safety questions, risk analysis quantified
[Beginners]
alan sailer
April 11, 2024, 01:44:32 AM
post Re: Tesla coil safety questions, risk analysis quantified
[Beginners]
Michelle_
April 11, 2024, 01:31:40 AM
post Re: Plasma Torid - Class E Self Resonant Dual/Stereo - Plasma Torid Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
OmGigaTron
April 11, 2024, 01:11:00 AM
post Re: Tesla coil safety questions, risk analysis quantified
[Beginners]
alan sailer
April 11, 2024, 12:58:52 AM
post Re: Tesla coil safety questions, risk analysis quantified
[Beginners]
Michelle_
April 11, 2024, 12:31:37 AM
post Re: Plasma Torid - Class E Self Resonant Dual/Stereo - Plasma Torid Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
April 11, 2024, 12:30:21 AM
post Re: Tesla coil safety questions, risk analysis quantified
[Beginners]
alan sailer
April 10, 2024, 11:41:46 PM
post Re: Tesla coil safety questions, risk analysis quantified
[Beginners]
Mads Barnkob
April 10, 2024, 11:33:32 PM
post Re: Tesla coil safety questions, risk analysis quantified
[Beginners]
Michelle_
April 10, 2024, 10:41:33 PM
post Re: Tesla coil safety questions, risk analysis quantified
[Beginners]
MRMILSTAR
April 10, 2024, 10:31:31 PM
post Tesla coil safety questions, risk analysis quantified
[Beginners]
Michelle_
April 10, 2024, 09:56:35 PM
post Re: Drsstc voltage spike question
[Dual Resonant Solid State Tesla coils (DRSSTC)]
unrealcrafter2
April 10, 2024, 08:59:26 PM
post Re: Drsstc voltage spike question
[Dual Resonant Solid State Tesla coils (DRSSTC)]
markus
April 10, 2024, 06:35:30 PM
post Re: Drsstc voltage spike question
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
April 10, 2024, 05:35:14 PM
post Medium Drsstc question
[Dual Resonant Solid State Tesla coils (DRSSTC)]
unrealcrafter2
April 10, 2024, 03:07:02 PM
post Re: Plasma Torid - Class E Self Resonant Dual/Stereo - Plasma Torid Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Michelle_
April 10, 2024, 03:42:12 AM
post Re: Plasma Torid - Class E Self Resonant Dual/Stereo - Plasma Torid Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Michelle_
April 10, 2024, 03:41:04 AM
post Re: Plasma Torid - Class E Self Resonant Dual/Stereo - Plasma Torid Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
sky-guided
April 10, 2024, 02:50:23 AM
post Re: DRSSTC V1 using BSM1500
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Unrealeous
April 10, 2024, 01:32:17 AM
post Re: Plasma Torid - Class E Self Resonant Dual/Stereo - Plasma Torid Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
OmGigaTron
April 10, 2024, 01:26:29 AM
post Re: Plasma Torid - Class E Self Resonant Dual/Stereo - Plasma Torid Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
OmGigaTron
April 10, 2024, 01:18:35 AM
post Re: Big Coil Big Sparks
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Mads Barnkob
April 09, 2024, 07:34:19 PM
post Re: DRSSTC V1 using BSM1500
[Dual Resonant Solid State Tesla coils (DRSSTC)]
flyingperson23
April 09, 2024, 06:14:27 PM
post Re: CM400 Induction Heater
[Electronic Circuits]
markus
April 09, 2024, 06:08:53 PM
post Re: DRSSTC V1 using BSM1500
[Dual Resonant Solid State Tesla coils (DRSSTC)]
markus
April 09, 2024, 05:15:19 PM
post Re: Plasma Torid - Class E Self Resonant Dual/Stereo - Plasma Torid Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Michelle_
April 09, 2024, 05:11:04 PM
post Re: Big Coil Big Sparks
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Benjamin Lockhart
April 09, 2024, 06:32:16 AM
post DRSSTC V1 using BSM150
[Dual Resonant Solid State Tesla coils (DRSSTC)]
Unrealeous
April 09, 2024, 04:04:47 AM
post Re: Plasma Torid - Class E Self Resonant Dual/Stereo - Plasma Torid Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
April 09, 2024, 03:27:11 AM
post Re: Big Coil Big Sparks
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
April 09, 2024, 03:25:47 AM
post Re: Plasma Torid - Class E Self Resonant Dual/Stereo - Plasma Torid Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
OmGigaTron
April 09, 2024, 03:01:40 AM
post Re: Plasma Torid - Class E Self Resonant Dual/Stereo - Plasma Torid Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
sky-guided
April 09, 2024, 02:46:46 AM
post Re: Plasma Torid - Class E Self Resonant Dual/Stereo - Plasma Torid Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
OmGigaTron
April 08, 2024, 09:32:57 PM
post Re: Plasma Torid - Class E Self Resonant Dual/Stereo - Plasma Torid Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
OmGigaTron
April 08, 2024, 09:25:11 PM
post Re: Plasma Torid - Class E Self Resonant Dual/Stereo - Plasma Torid Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
April 08, 2024, 08:45:15 PM
post Re: Plasma Torid - Class E Self Resonant Dual/Stereo - Plasma Torid Build
[Dual Resonant Solid State Tesla coils (DRSSTC)]
OmGigaTron
April 08, 2024, 08:24:13 PM
post Big Coil Big Sparks
[Dual Resonant Solid State Tesla coils (DRSSTC)]
alan sailer
April 08, 2024, 04:02:48 PM
post Re: First DRSSTC SKM100
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
April 08, 2024, 03:45:30 AM
post Re: Oversize Snubber Capacitor
[Dual Resonant Solid State Tesla coils (DRSSTC)]
thedark
April 08, 2024, 03:35:32 AM
post Re: Oversize Snubber Capacitor
[Dual Resonant Solid State Tesla coils (DRSSTC)]
davekni
April 08, 2024, 03:12:45 AM

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