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Messages - davekni

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1
Simulating spark gaps is a bit tricky.  For most uses, a simple switch is sufficient.  Instantaneous elements such as switches are problematic for analog simulation. LTSpice does reasonably well with instantaneous events, but still sometimes gets stuck (step time becomes too small until the simulation errors out).    LTSpice does have switch elements along with arbitrary behavioral voltage and current sources that can be used to control the switch. Sometimes I've used thyristors instead (NPN and PNP connected into a latching circuit) with diode breakdown defining the trigger voltage.

2
Interesting project!  I'm also finishing up a DIY plasma ball, documented on this forum:
https://highvoltageforum.net/index.php?topic=924.msg6187#msg6187

Ended up using some small transformers from EBay because they fit in my box better.  But initially I fried the diodes in an old DC flyback transformer.  Frying them completely required more than just full-out over-voltage.

Wanted to avoid much total power into the diodes to avoid frying neighboring windings, so used short pulses.  Frying took two steps.  First drove the flyback with sine-wave bursts on the primary (from a ZVS circuit) with a HV capacitor on the secondary.  Increased voltage of the bursts until avalanche-breakdown of the diodes.  This was a single event once the voltage got high enough.  (Output capacitance is needed to maintain the positive output voltage so that the diodes experience max voltage during the negative half cycles.)

Unfortunately, this only partially fried the diodes, down to ~2-3kV.  To finish frying, shorted the primary winding and discharged a 11nF capacitor to the secondary through a spark gap.  Discharges repeated ~10 times per second, every time the capacitor charged enough to trigger the spark gap.  Required several minutes of this to get well-shorted diodes.

I've heard that the Sanyo F0239 and F0241 flybacks are AC.  The latter is on EBay for $29.  Don't have any personal experience with these.

3
Spark Gap Tesla Coils (SGTC) / Re: 230 volts spark gap
« on: February 19, 2020, 03:53:13 AM »
10A would almost certainly be too much.  Depending on the actual voltage split between the 2.2kW kettle and your circuit, the current might be low enough.  A fan blowing on the transformer would allow slightly more current.

4
Voltage Multipliers / Re: Doorknob vs Ceramic Disk
« on: February 18, 2020, 05:33:22 AM »
kilovolt,

LTSpice is the tool I'm familiar with.  Use it at work and at home.  I hear about other free options, but have no personal information on those.  When LTSpice first came out, I ran some comparisons with other simulators.  LTSpice seemed to converge better and run faster on complex circuits than some of the commercial paid simulators.  I don't think it's being improved any more, so other simulators may have caught up or surpassed LTSpice by now. When I worked for Tektronix, their internally-written simulator was much better than any commercial option.  (I was on a team that evaluated the possibility of Tektrnix selling it as a commercial simulator, but such would have required 10x larger a group for documentation and support etc.)  Freescale's internal MICA simulator is the next best one to my knowledge, but also not publicly available.  My use of MICA is a decade or so old as well, so its ranking may no longer be valid either.

Yes, I've built three Tesla coils.  The latest is a DRSSTC documented on this forum:
https://highvoltageforum.net/index.php?topic=798.msg5332#msg5332
I plan (perhaps in 2021) to try something somewhat like QCW - to increase primary capacitance as the arc length increases during each firing - discussed some in the above link.  Haven't played with vacuum tubes for many decades, and never high power ones.

Yes, projects take too much time.  Even though my "kids" are out on their own, I'm still working and volunteering (science activities for Foster-Parent-Night-Out events mostly), so project progress is slow.  Keep family as the higher priority as they should be.

5
The white LED's I've pulsed at 0.3us didn't have a significant tail, although I was viewing them in monochrome.  Being interested in monochrome only, deep red and deep blue LEDs were more efficient, but large white LEDs are much more available and cheap, so I tested some of those too.  I've had a life-test running for the past 3 years or so of a blue LED rated for 1A continuous 2A peak, driven with 25A 0.3us pulses at ~200Hz repetition rate.  White LEDs should be similar in that respect, being made from blue and phosphor.

6
Spark Gap Tesla Coils (SGTC) / Re: 230 volts spark gap
« on: February 17, 2020, 03:59:59 AM »
John gave you the answer, but you can also get that information and more by a simple google search of the writing on the part.  Try searching for "MEX-X2 MPP 1.0K 275V 40/100/21".  This works for many parts.

Concerning microwave transformer current, look for the power rating of the microwave it came from (or a typical microwave if you don't know).  Use that power and the line voltage it was designed for (ie. 230V) , and calculate a current.  The actual will be a bit higher due to power factor and losses in the magnetron, but that provides a lower limit to the likely value.

7
Voltage Multipliers / Re: Doorknob vs Ceramic Disk
« on: February 15, 2020, 05:41:13 AM »
Kilovolt,

With 3300uF bulk cap, power factor is likely around 60 to 65%, for ~4kW of real power.  This is now based on LTSpice simulations.  Does depend on variac inductance, both parallel and leakage (series).  With different assumptions, ranges from 50% to 70%.

If the diode peak current during charging is higher than the ~0.5A discharge, then the X-Ray transformer must have quite low leakage inductance.  For 5kW (2.5kW per tower) and 50kVpp, average current of the bottom diodes should be 50mA.  I'd expect transformer inductance to spread out the current pulses to 60 degrees or so of the sine-wave cycle, but it could be shorter with low leakage inductance.  So, perhaps peaks of >10x average are possible.  Agreed that for your power level, 100mA diodes was a great choice.

Not suggesting it is worth the work, but if you want to measure peak diode current:  I'd suggest 50-ohm coax with 50-ohm termination resistors at both ends.  Wind as many turns as possible around a large ferrite core (E-core or toroid) for a common-mode choke.  One end of the coax in series with the ground connection of the bottom capacitor of a tower.  Other end to an oscilloscope.  Current is, of course, 25 times measured voltage.

I don't have any construction pictures for my large multiplier, but here's a schematic and image of the finished product:




This project was ~7 years ago, so my memory isn't perfect.  I think the diodes were 10mA 20kV.  The bottom stages used two diodes in series, as the voltage per stage is a bit lower farther up the string.  Caps near the bottom were 30kV, upper ones 20kV.  All the caps were cheap ceramic disk caps.  A couple bottom caps failed early on driving it at 20kHz.  I think the current from just stray capacitance was enough to overheat them.  Dropped to 700Hz after that initial failure - using a spark coil feed.  The caps and diodes are potted and glued to the outside of 1.5" PVC pipe using silicone rubber caulk.  (The silicone that gives off alcohol during cure, not the acetic acid type.)  That pipe is centered inside the 6" PVC outer pipe visible in the picture.  Top is a 10" stainless steel garden-gazing ball.  The multiplier is the lower ~60% of the height.  The upper ~40% is a string of 32 10meg 10kV (peak) resistors, also attached and potted with silicone rubber.

The large output resistance is is for safety.  Primary use is to charge people, making their hair stand up and/or launching foil pie tins from their hand.  For that use, ~100kV is sufficient.  I ran it to 250kV shortly after construction just to see what the upper limit was.  It hasn't been that high since.  Gets used a few days a year at different events.

Given the high output impedance, the only way I could measure voltage was by placing progressively heavier (thicker) metal disks on top to see if they could lift off by electrostatic repulsion.  (Weight per unit area is what matters here, along with the radius of the top ball.)  Even my 1G-ohm resistor strings load down the output too much, due to the 320meg output resistance and due to small capacitors with only 700Hz drive.  (That effect was much less at my original 20kHz.)  Measuring with resistor strings was also affected by the ion wind that added a bit of extra current.  Probably could have shielded enough to fix that issue.

I found your comments about charging walls and other objects around quite interesting.  I have that problem when in smaller rooms.  It takes more voltage to get hair to stand up later in the day, as the charged walls and ceiling repel the hair.  Neighboring stations notice all their objects getting charged too.

8
Voltage Multipliers / Re: Doorknob vs Ceramic Disk
« on: February 14, 2020, 05:42:19 AM »
Kilovolt,

At 25-30A, the variac reactive power is probably not very significant.  Even 10A out of 30A still leaves sqrt(800) = 28.3A.  The more significant part of power factor is likely from any bulk capacitance after the bridge rectifier.  Do you have bulk capacitance there, or does your inverter power track the rectified line voltage?

Yes, I expected operating power would be higher than short-circuit power.  That's why I used 4kW for the diode-current calculation example.  Even that is probably low given your line current measurements.

With 800k total series resistance, you are way below those diode's 10A surge current rating.  700kV would allow just under 1A peak discharge current, of which the diodes take half, so under 0.5A surge.

Nice project!  My largest CW multiplier is for a Van der Graaf generator alternative, so very low current.  It's max is about 250kV with a 300meg output resistor string.

9
Voltage Multipliers / Re: Doorknob vs Ceramic Disk
« on: February 13, 2020, 05:44:24 AM »
Andrew,

As a simple approximation, open-circuit voltage determines the distance over which an spark/arc can be started.  (Electrode shape matters too.)  Average current determines the thickness of the arc.  Voltage drops as the arc forms, allowing current to increase.  The details of spark vs. arc are complex and not a subject I know much about.

To make impressive arcs, high power is the first criteria.  Kilovolt mentions his transformer being good for 6 or 7kW, but it's not clear if his entire system is running that high.  Based on his 800k-ohm output ballast resistance and 35mA short-circuit current, that's about 1kW into the resistors.  Peak power is likely higher, but I don't know how much.  Perhaps kilovolt has some input power measurements he would be willing to share.

Diode currents drop linearly up the CW multiplier tower.  Bottom diode average current can be estimated by the transformer output Vpp and power (per tower).  If running 50kVpp and 2kW per tower, that's 2kW/50kV = 40mA average current per diode.  Short-circuit conditions are likely lowering the Vpp input, so will increase diode current for a given power.  So, if you want to replicate Kilovolt's results, and if he is running around 4kW (2kW per tower), then you'll need a 4kW system.  Diode current then depends on Vpp AC feed.

10
Spark Gap Tesla Coils (SGTC) / Re: NST
« on: February 13, 2020, 03:57:38 AM »
Hopefully someone with direct experience will answer too.  A high spark frequencies I'd expect few issues.  At lower spark frequencies, there could be problems when the spark timing is close to line frequency.  If sparks hit only the positive half-cycles for example, there would be DC current draw on the transformer, causing the iron to saturate.  At really low spark frequencies, there could possibly be an issue if the MMC capacitance and transformer leakage inductance happen to resonate at the line frequency.  I think only larger-than-normal MMC capacitance could cause such a problem.

11
When you get to scoping, it would help to measure what signal-generator output amplitude is enough to barely make the driver function.  That would be reference point for scoped feedback signal.

When you say "enough to make the circuit oscillate", is this just single gate-drive pulses at ~60Hz?  If it is line noise, there may be some grounding issue.  A couple other possibilities:  Is the interrupter set for some fixed frequency of enable pulses?  The remaining signal could be single gate-drive pulses at the start of each enable pulse, as the typical UD2.7 etc. drivers do.  Another possibility is that, unlike UD2.7 etc., this driver is self-oscillating without feedback.  (Self-oscillating drivers don't appear common on this forum, but it's what I build for myself.  With self-oscillation tuned close to the operating frequency, the feedback signal can build over several cycles to get large enough, rather than needing to get there in the initial half-cycle.  No need for a resistor on the bridge output either.)  If this driver is self-oscillating, it may not be close to your resonant frequency.  Scoping should reveal the real situation.

If feedback amplitude isn't sufficient, the solution will depend on what amplitude is required.  The UD2.7 driver circuit requires around 100mV feedback to start oscillating, into a 50-ohm load on the current transformer secondary.  If your driver is similar, but your feedback amplitude is lower, then we need to figure out why your amplitude is low.  If your driver requires much higher amplitude, then either an external preamp or modification to the driver is in order.  (In this latter case, you could see if it's possible to trace the feedback input circuit on the driver - load resistance, clamping, comparator circuit - the signal conditioning circuitry before entering the FPGA.)

Good luck!

12
Transformer (Iron Core) / Re: Microwave Oven Transformer
« on: February 12, 2020, 04:56:19 AM »
kilovolt,

There's obviously very limited data on human electrocution parameters - a few case studies and extrapolation from animal experiments.  The operative words before 0.25A are "well below".  0.25A at 60Hz is what I recall reading in a book in high school (45 years ago) as the current having a 50% chance of causing death.  (Or perhaps it was 0.25A at 50Hz and 0.22A at 60Hz.  82Hz was listed as the peak human sensitivity frequency.)  Of course, that depends on duration, size of the person, etc.  The limited bit of information I can find from web searching now is summarized on this page:
https://hypertextbook.com/facts/2000/JackHsu.shtml

Their range of 0.06 to 0.2A appears to be more of a 99% survival threshold than 50/50%.  There are cases of humans surviving (with severe burns) thousands of amps, perhaps because the plasma path engulfing them shunts much of the current after the initial few milliseconds.

I had a "friend" in high school who had a large 12kV 60mA NST.  He also had a very troubled home life.  One evening he decided to see what 60mA felt like, so grabbed the two output terminals, one in each hand.  60mA was beyond the let-go threshold, so he was stuck clenching both terminals.  Fortunately for him, he managed to pull the line cord with a foot.

Ballasting to 5ma would make it rather safe.  For 5mA, a microwave transformer is probably not the right starting point.  Ballasting to 0.1A would drastically reduce the chance of death on accidental contact, so could be valuable as an added safety feature.  Sounds like this project needs more current than that, so extreme care not to touch is the only option.  (Accidental touching with the back of a hand is much less hazardous than the inside of a hand, as the current-induced muscle contraction pulls away from contact.)

13
Transformer (Iron Core) / Re: Microwave Oven Transformer
« on: February 10, 2020, 05:34:10 AM »
If you can find two more microwave oven transformers and a steel-capable band or chop saw:  Cut the two transformers in half (easier after removing the shunts) and join the two primary halves at their cut surfaces with a shim.  Parallel the two windings.  (Check phasing to avoid anti-parallel.)  The two in parallel can handle the line current reasonably efficiently (where a single one is over-driven as Steve mentioned).  Adjusting the shim controls the inductance and therefore the amount of ballasting.

14
Transformer (Ferrite Core) / Re: Mazilli ZVS Driver Modification Problems
« on: February 10, 2020, 05:29:33 AM »
Andrew,

Wonderful!  I'm thrilled for you, and for the confirmation of what I plan to try next time I make a ZVS circuit.

15
Voltage Multipliers / Re: Doorknob vs Ceramic Disk
« on: February 10, 2020, 05:26:26 AM »
Andrew,

Glad it's making sense!  Yes, smaller capacitors on the AC-fed column will allow lower output resistance.  The output current splits by the capacitor ratio.  If the DC output column capacitors are 10 times larger, then they'll supply 10/11ths of the discharge current and the AC-fed column will supply 1/11th (9%).  As you mentioned, it will take more cycles to charge that way.

Those diodes are relative slow.   For CW multiplier use, the caps need to feed the reverse-recovery charge of all the diodes.  So, I'd use these for at most a few kHz.  They do have a nice large surge-current capability - 30A for one 60Hz cycle.

I've found it difficult to find fast HV diodes in normal electronics parts distribution.  I've gone to Chinese parts from EBay, and had good luck so far.  Depending on the voltage you need, here's some links for 30mA at 15, 20, 25, and 30kV:
https://www.ebay.com/itm/HVRT150-30mA-15KV-100nS-HV-Rectifier-High-Voltage-Diode-20pcs/401463844295?hash=item5d791c1dc7:g:008AAOSw0W5aO87s
https://www.ebay.com/itm/10pcs-2CL20KV-30mA-High-Voltage-Diode-Rectifier-HF-Tesla-Coil/382415572940?_trkparms=ispr%3D1&hash=item5909be8fcc:g:JhcAAOSw76JcMyne&enc=AQAEAAACQBPxNw%2BVj6nta7CKEs3N0qVIA%2Fl%2BWrTfyJdvQbYaSA2PBSlY61x5eAYWC3QVGs6DO4Rxigadgx9P7cC56%2FLhFkz%2BVNddX75pW%2B%2FBD5%2FMgw%2FtLtaNEXXe9zJS205l7oupX1ZPywMBo%2BENdoHueQA4x2whiqCI41WIdcCuAOAsZPNpCMK8FOHVpE2ioFhTbLiqyzIQmMhw1txTN9AiBimqf%2BCVNt93TRf4MMZ95I0O1vXH2YfnTHTeZDvZOeEQuSp0lvY3NAmffmGlwgN89pogxre5HV0iIOciidPsaiivq8gZ4PbD%2B%2FbJ0wSTeMcrbu%2F2NORy3y5R0J%2B%2Brc0jfvQGNXN0tUKgjKF0ZTbOJXdrp%2BQni7gzDHbZwjN2Ps7om3zJj4ra2QK%2FSMPUSdbhRpyWjRCJrJjMvvzkyL8Q8oP6sPtbqD4iOQ02OJC3PYfiTD7GQv2e2Ci%2BuPeTaeMczvrkUyjEIMC4Mt1QBHCAmJjlPjlmsECaB%2FZCrOwVmvTKmUn5aw7Zdhl08Wvmh%2F83QiSlatYwHrS%2BPcSohsfRa3YhYwyBg4dNecwMIX8eDwtdLKU2Hj%2F6mbcCystoDuz%2B9GuqBKaBZCLqhm1fjr%2FAVMDyTxt1FQqcip32YRiM9Q%2Fk%2FSJm0T%2BkfupeiM8kHWQi8RVo%2F9B8IEVIpH0MRI2ENBqkDwwdfcmOMnXhjvhAATgDUhBpg%2BPBIHLpUer5%2FAzPOCkybzbKKbDBDlxyPqFCBAczp%2BRm19RfLhVf84Uhk62qzgtLqQ%3D%3D&checksum=382415572940a42d186c494248ed8d1f8803446e0d3b
https://www.ebay.com/itm/US-Stock-12x-2CL25KV-25KV-30mA-100nS-High-Voltage-Diode-Rectifier-HF-Tesla-Coil/401295878181?_trkparms=ispr%3D1&hash=item5d6f192825:g:L6oAAOSwVrBalm5t:sc:ShippingMethodStandard!97070!US!-1&enc=AQAEAAACQBPxNw%2BVj6nta7CKEs3N0qWj8RhVGMcqidy%2FrYqjIDyalLsvkMdDJZC82HCKjYL3isishWWhioPJhD22hZVdiPy099u22UhUvMwamHIV%2BSKzy6v%2BxFxQMD%2FuNkhaKBIGOE1PRQUfA0CvOfa%2FNYaXwmoAm6kscbukmw1phGpa6It8ARS59Cl4devhi3SopK%2F4z%2FP442lUA7v1Lbg4abvyo%2FE3Pq6HTLKzH0%2FDonRaVOGyQTFb5X8MhytsP0lc%2FR8%2BQF10QzHJqRcOz7PcZf9H%2F82HiwUgedb1jKUGckkBHlXtmpjpTQNo3d1rBPudd01zD2t5pMgnJUbQ47ApIKAcBQXd5PHrOnXQ6HJ9Mslb1b6DCePS2quVjQeAvFjuhGa0W%2F60nlpygVPCBRTWjURR3heuuC05hECWVRxZ2x6d7X1OMVSGXLPmP1ZF2a01DjNSrmCJjr%2F9z6u9%2FcJxxHXZEwvfQekz%2FP21IpMfWqWxj2tYLI2sDDn5CpoJwSCVq3F5FaKqK6MP1clhuOU4c6HQIfKKhaY%2F3LxrKiHbFAfdEnu9Vz5zn3Ox6WVEt2IQXxqwE%2FfH0ZpoE8efHvHK6SolMwWkwR%2B1qZABQC0HoiMn5W0rTEztgPn70o0Fs3%2B%2Bh%2BuB0DPsPAgVPSjPHgKKSMiJid0SswzvBBGQO8YwqrcLaziucs4Otsfvag75kOXwJA7UUBt36%2BGaKT0DlzkrecN6c9IuuHrJVcfQOC3SwkPNjOhqHMLEpn%2Feu0AH5lBGx68XJQ%3D%3D&checksum=401295878181c7ef6e17669144b58fb84364e997aaf3
https://www.ebay.com/itm/6pcs-30mA-30KV-100nS-High-Voltage-RECTIFIER-Diodes/153434145388?hash=item23b963426c:g:tnIAAOSw-FpbL7mC

5mA versions are much more available, but that may not be enough for your plans.

For the diodes, reverse DC voltage is easiest to understand, but AC voltage is just sqrt(2) lower (presuming full-wave rectification).  If you are referring to the capacitors, they do experience some AC voltage (due to the AC current), which can be the cause of failure for cheap disc ceramic caps.

16
Spark Gap Tesla Coils (SGTC) / Re: 230 volts spark gap
« on: February 10, 2020, 04:56:27 AM »
I agree that E/I silicon-iron (transformer steel) laminations are about as good as it gets for line-frequency inductors.  (Cobalt alloys are better, but quite expensive.)  Klugesmith, did you mean "find a larger core"?  For more stored energy and/or better efficiency (less winding power loss), a larger core is better.

If you can get a couple microwave oven transformers and access to a steel-capable band-saw or large chop-saw, two primary halves wired in parallel and physically stacked with a small gap works well for line-frequency inductance.

17
Do you have an oscilloscope available?  I'm not sure how to help without some scope traces.

Have you found schematics for your purchased controller?  A couple possibilities come to mind at the moment.  One is that the controller needs more feedback voltage than most.  (UD2.7 is the only controller I've studied other than my own home-made one.)  To test this, you could run (at low power) from your signal generator, then lower the signal generator output amplitude until it quits working.

The other possibility is that the controller is set to run continuously rather than enabled in pulses.  Most drivers create one gate-drive edge at the start of each enable pulse.  That edge needs to create enough feedback to start the oscillation.  If either that initial edge is missing, or the generated feedback amplitude is too low, then it won't work.  (Scoping that gate-drive output, half-bridge output, and feedback signal would answer a lot of questions.)

18
Spark Gap Tesla Coils (SGTC) / Re: 230 volts spark gap
« on: February 09, 2020, 06:23:41 AM »
With the I-pieces separate as you show, it's easy to add a gap.  You may already have somewhat of a gap due to laminations not exactly lining up at the joint between E and I pieces.

Adding a small gap also makes inductance vs. current much flatter.  The permeability of silicon-iron (transformer steel) varies significantly as flux density increases.  The gap is linear (air), making the resulting inductor more linear.

To calculate saturation current, you'll need the saturation field of silicon-steel, around 1.6 to 1.7T if I recall correctly.

19
Voltage Multipliers / Re: Doorknob vs Ceramic Disk
« on: February 08, 2020, 06:55:44 PM »
Both (or all three in the "full wave" case) of the capacitor columns are charged to the same high voltage.  One is static, in the sense that the bottom end is tied to ground and the top end is the multiplier output.  The other is fed with AC at the bottom.  The DC voltage across each capacitor in each column is roughly the same.  (Except the bottom capacitor of the AC-fed column has half-voltage).  When the output arcs to ground, all the capacitors get discharged.  The output column discharges directly.  The AC-fed column(s) discharge through the diodes.

Another way to look at it:  Consider a 10kVpp AC input to a 10-stage multiplier.  19 of the capacitors have 10kV DC across them.  (The bottom AC-fed capacitor has only 5kV, as it's half-wave rectified version of the input AC voltage.)  So, the output is 100kV DC.  The top of the AC-fed capacitor column is oscillating between 90kV and 100kV.  If the output is discharged from 100kV to 0V, the top of the other column can't remain at 90-100kV.  The diodes conduct to pull it down too.

CW multipliers are ideal for providing DC voltage.  For making arcs, the necessary resistors lower efficiency.  Marx generators are another option for high-voltage DC arcs, but they have their own set of efficiency losses.

20
Transformer (Ferrite Core) / Re: Mazilli ZVS Driver Modification Problems
« on: February 08, 2020, 06:29:10 PM »
Yes, that's the correct connections for the gate-drive soft-start diode.  There's no need to switch it off.  That's what the diode is for.  Once line power is switched on, the ZVS input inductor is at 170V.  The diode blocks that 170V from feeding back to the 40V gate-drive supply.  (Without a diode, the gate-drive would fry at 170V.)

If your power is rectified line voltage without filter capacitors, then it will drop below 40V momentarily at each line voltage zero-crossing.  The gate-drive supply will feed a little bit of current at those zero-crossings (120 times per second).  Shouldn't be an issue for this case either.

If you go with gate-drive, I'd love to hear how it works.  I haven't tried that option yet - didn't think of it quite in time for my last ZVS project.  Expect it will work, and avoid a high-power resistor.

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[Voltage Multipliers]
rikkitikkitavi
February 19, 2020, 10:43:13 AM
post Re: Help!Capacitor that burns out after a while!
[Voltage Multipliers]
Peregrine
February 19, 2020, 06:54:14 AM
post Re: Help!Capacitor that burns out after a while!
[Voltage Multipliers]
klugesmith
February 19, 2020, 06:51:52 AM
post Re: 230 volts spark gap
[Spark Gap Tesla Coils (SGTC)]
davekni
February 19, 2020, 03:53:13 AM
post Re: Help!Capacitor that burns out after a while!
[Voltage Multipliers]
ElectroXa
February 18, 2020, 09:44:25 PM
post Re: Help!Capacitor that burns out after a while!
[Voltage Multipliers]
MRMILSTAR
February 18, 2020, 09:34:06 PM
post Re: Help!Capacitor that burns out after a while!
[Voltage Multipliers]
Peregrine
February 18, 2020, 08:27:31 PM
post Re: Help!Capacitor that burns out after a while!
[Voltage Multipliers]
Weston
February 18, 2020, 07:55:14 PM
post Re: Help!Capacitor that burns out after a while!
[Voltage Multipliers]
Peregrine
February 18, 2020, 07:32:04 PM
post Re: Help!Capacitor that burns out after a while!
[Voltage Multipliers]
klugesmith
February 18, 2020, 05:58:39 PM
post Re: Help!Capacitor that burns out after a while!
[Voltage Multipliers]
MRMILSTAR
February 18, 2020, 05:16:55 PM
post Re: Help!Capacitor that burns out after a while!
[Voltage Multipliers]
Peregrine
February 18, 2020, 04:19:37 PM
post Re: Help!Capacitor that burns out after a while!
[Voltage Multipliers]
Mads Barnkob
February 18, 2020, 04:12:11 PM
post Re: 230 volts spark gap
[Spark Gap Tesla Coils (SGTC)]
Quentief
February 18, 2020, 01:25:06 PM
post Help!Capacitor that burns out after a while!
[Voltage Multipliers]
Peregrine
February 18, 2020, 10:40:58 AM
post Re: How can I make my driver better
[Solid State Tesla Coils (SSTC)]
Mads Barnkob
February 18, 2020, 09:02:23 AM
post Re: DIY 250W LED Flood Light for High Speed Filming
[Light, Lasers and Optics]
Mads Barnkob
February 18, 2020, 08:58:38 AM
post Re: Doorknob vs Ceramic Disk
[Voltage Multipliers]
davekni
February 18, 2020, 05:33:22 AM
post Re: DIY 250W LED Flood Light for High Speed Filming
[Light, Lasers and Optics]
davekni
February 18, 2020, 05:08:28 AM
post How can I make my driver better
[Solid State Tesla Coils (SSTC)]
Irido
February 18, 2020, 04:45:06 AM
post Re: DIY 250W LED Flood Light for High Speed Filming
[Light, Lasers and Optics]
klugesmith
February 18, 2020, 02:44:42 AM
post Re: HP T620 Thin Client - PSU Hack And Windows PC Modification
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
latethannever
February 18, 2020, 01:58:48 AM
post Re: UV-cured cyanoacrylate glues?
[Light, Lasers and Optics]
Twospoons
February 17, 2020, 11:30:03 PM
post Re: DIY 250W LED Flood Light for High Speed Filming
[Light, Lasers and Optics]
Twospoons
February 17, 2020, 11:21:14 PM
post Re: DIY 250W LED Flood Light for High Speed Filming
[Light, Lasers and Optics]
Mads Barnkob
February 17, 2020, 10:45:52 PM
post Re: DIY 250W LED Flood Light for High Speed Filming
[Light, Lasers and Optics]
ElectroXa
February 17, 2020, 08:20:42 PM
post Re: DIY 250W LED Flood Light for High Speed Filming
[Light, Lasers and Optics]
Twospoons
February 17, 2020, 08:02:29 PM
post Re: DIY 250W LED Flood Light for High Speed Filming
[Light, Lasers and Optics]
Mads Barnkob
February 17, 2020, 08:02:15 PM
post Re: DIY 250W LED Flood Light for High Speed Filming
[Light, Lasers and Optics]
haversin
February 17, 2020, 04:26:10 PM
post Re: HP T620 Thin Client - PSU Hack And Windows PC Modification
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
Mads Barnkob
February 17, 2020, 01:44:41 PM
post Re: HP T620 Thin Client - PSU Hack And Windows PC Modification
[Computers, Microcontrollers, Programmable Logic, Interfaces and Displays]
latethannever
February 17, 2020, 11:18:33 AM
post DIY 250W LED Flood Light for High Speed Filming
[Light, Lasers and Optics]
Mads Barnkob
February 17, 2020, 10:58:17 AM
post Re: Doorknob vs Ceramic Disk
[Voltage Multipliers]
kilovolt
February 17, 2020, 08:55:30 AM
post Re: Help for people buying the "12-48 Volt 1800/2500 Watt ZVS induction Heater"
[Electronic Circuits]
petespaco
February 17, 2020, 06:00:59 AM

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