DIY esd gun. - Page 1
Forum section: electronics / projects

author: newbadboy
author_rank: Regular Contributor
timestamp: December 22, 2022, 10:20:35 am
content: Just for fun and for learning intensions.It will handle 500V-7kV with 500V steps and will only have positive output polarity. It will have single shot and 10times @ 1Hz modes.

author: newbadboy
author_rank: Regular Contributor
timestamp: December 22, 2022, 10:21:49 am
content: more pics

author: newbadboy
author_rank: Regular Contributor
timestamp: December 22, 2022, 10:22:34 am
content: more pics

author: newbadboy
author_rank: Regular Contributor
timestamp: December 22, 2022, 10:23:16 am
content: more pics

author: mcinque
author_rank: Unknown
timestamp: December 22, 2022, 02:09:07 pm
content: this is interesting. do you want to share any schematics?

author: niconiconi
author_rank: Frequent Contributor
timestamp: December 24, 2022, 07:52:45 pm
content: Very cool. How did you make the discharge tip for the gun? Did you make your own drawings and ask a machine shop to have them custom made, or was it something else? I always want to make an industry-standard ESD gun but I don't have any mechanical knowledge.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: December 24, 2022, 09:29:06 pm
content: Huh, what's the dielectric strength of FDM like, anyway? Depends on fill and tuning? Is porosity ever low enough to use reliably (insulating large areas)?Tim

author: Zero999
author_rank: Super Contributor
timestamp: December 24, 2022, 10:53:09 pm
content: I've used a piezoelectric igniter before. The ones from disposable cigarette lighters work quite well. Of course it's just a rough test, not calibrated in any way.

author: joeqsmith
author_rank: Super Contributor
timestamp: December 25, 2022, 01:31:48 am
content: Nice looking project. It will be interesting to see the waveforms once you have it working.

author: niconiconi
author_rank: Frequent Contributor
timestamp: December 26, 2022, 12:07:14 am
content: Quote from: joeqsmith on December 25, 2022, 01:31:48 amTesting or calibrating the air-discharge waveform would probably be the most tricky one... IEC 61000-4-2 requires the use of special lab room setup with ground planes, resistors, and shielded cable going into a large shielded box for all the instrumentation... Fortunately for a quick qualitative pre-compliance test instead of traceable quantitative measurements, you probably don't need it...Transmission Line Pulse is an alternative component-level ESD test method precisely due to the unpredictability of gun-type tests...

author: SiliconWizard
author_rank: Super Contributor
timestamp: December 26, 2022, 12:12:17 am
content: Quote from: Zero999 on December 24, 2022, 10:53:09 pmSame here.

author: Karel
author_rank: Super Contributor
timestamp: December 26, 2022, 12:49:41 am
content: I use a Milty anti-static gun for (rough) testing. I extended the electrode a bit so that it's more exposed and Iattached a grounding wire to the trigger. It's pretty effective.

author: Swainster
author_rank: Frequent Contributor
timestamp: December 26, 2022, 06:15:19 am
content: My experience with HV (at a few 10s of microamps) and FDM in prototype construction is that you can treat the plastic as a perforated for HV purposes I.e. it goes straight through it. You need to rely on the air gap (taking into account creepage) for any insulation. For that matter, even bog standard injection moulded plastic has a significant chance of failure over time, due to imperfections/air bubbles picked up in the shot. Silicone tubing can be used to supplement things though. Surprisingly (at least to me) vinyl tubing is absolutely rubbish at HV isolation.

author: fcb
author_rank: Super Contributor
timestamp: December 27, 2022, 01:32:42 pm
content: Good luck - be interesting to see the results. Have you got a fast scope to check rise-times?Have you used a mercury wetted relay? Looks like a Pickering 67 series - dry relay? What is your target max discharge voltage? Discharge tips are also typically a ball not a point (more difficult to turn!).

author: newbadboy
author_rank: Regular Contributor
timestamp: January 02, 2023, 08:41:18 am
content: Quote from: T3sl4co1l on December 24, 2022, 09:29:06 pmI have no idea. just hoping (and believeing) that having alot of space and infill will work.

author: newbadboy
author_rank: Regular Contributor
timestamp: January 02, 2023, 08:42:05 am
content: Quote from: niconiconi on December 24, 2022, 07:52:45 pmI have a friend that has a mechanical workshop that made it for me

author: newbadboy
author_rank: Regular Contributor
timestamp: January 02, 2023, 08:43:14 am
content: Quote from: SiliconWizard on December 26, 2022, 12:12:17 amAs mentioned before, it will only handle contact

author: newbadboy
author_rank: Regular Contributor
timestamp: January 02, 2023, 08:47:10 am
content: Quote from: fcb on December 27, 2022, 01:32:42 pmI have not measured it yet, waiting for my HV diff probe, my scope is fast enough but the diffprobe is 100MHz so it will probably limit the measurement capabillity. Yes i use the pickering relay due to cost factor. It will be driven out of specc but should work. Max 7kV is the goal.The ball discharge tip are for air disharge, i will only use it for contact which then is the point tip.

author: newbadboy
author_rank: Regular Contributor
timestamp: January 02, 2023, 08:50:27 am
content: I did a small startup of the HV part.First attempts kind of failed. When injecting 6V of 10kHz the secondary output was 170Vdc. Also the LDO powerin the primary went down all the time like if it went into protect mode.I guees i will need to tweak it a bit more

author: newbadboy
author_rank: Regular Contributor
timestamp: January 02, 2023, 09:00:30 am
content: Quote from: mcinque on December 22, 2022, 02:09:07 pmSure, will upload soon

author: EggertEnjoyer123
author_rank: Frequent Contributor
timestamp: January 02, 2023, 09:07:51 am
content: I'd suggest using a similar circuit (but with a capacitor connected in parallel with the inductor coil). You'll probably need to experimentally determine its value.The way these transformers usually work is that you put current through the primary, then you quickly shut it off and the collapsing magnetic field makes a massive voltage on the secondary. The circuit provided (which I stole from the chinese seller's website) does that and it should work (with the capacitor added, and maybe a few protection diodes to make sure you don't blow up your transistor). These transformers will not put out anywhere close to the rated voltage if you drive them normally (with a function generator). Voltage feedback can be accomplished using a resistor divider and a comparator, and it can be used to change the duty cycle (maybe consider using a dedicated switcher IC instead, like the UC3845). Just make sure everything is stable, which is easier said than done.

author: newbadboy
author_rank: Regular Contributor
timestamp: January 02, 2023, 10:00:40 am
content: I don't have access to my laptop so i cannot share the full schematic at the moment.The drawing you attached is basically what i'm doing. At least what i believe. I have a transistor down to ground with 10kHz square wave. The upper part is then supplied with a variable LDO to ba able to set out outputvoltage by altering the input voltage. I don't really have any controll of how energized the coil is in reality but that might be the issue hereof course i have protection diodes alsoWhat am i missing

author: fcb
author_rank: Super Contributor
timestamp: January 02, 2023, 10:27:18 am
content: You need feedback from the HT generator to detect both sparking and to regulate/set the HT.I'd probably have gotten higher than 170V before going to the bother of designing a case.Designing HT supplies is non-trivial, you'll probably want to pot things in clear silicone/RTVwhen you get higher. Also, when a discharge happens you can easily nail the FET/transistor, so look at adding protection in the form of over-current and over-voltage.If you are going single polarity then LOPT's might be better to start with, they are designed to work around 16KHz and have the output rectifier diode(s) built in and are designed to drive a capacitive load (eg CRT).Also, if it's contact only, then I'd be tempted to just use the relay to discharge/safe the probe-tip (via a few hundred K) when the trigger is released.

author: newbadboy
author_rank: Regular Contributor
timestamp: January 02, 2023, 01:36:33 pm
content: My intent is to measure what the LDO needs to output to set certain secondary voltages. Feedback should not be needed?I hope to be able to step up the out output with 500V steps from 500 till 7kV. This by regulating the primary voltage. In reality the ldo is controlled by a mcu and a digital pot.There is a guy making a esd gun on youtube with the exact same transformer as i use and he has no problems getting 10kV out of it. He is using the 555 as pulse generator and the LM317 as primary voltage source to set the output level.Yes adding more protection to FET is probably a good idea.I'm not sure what LOPT stand for, sorryDischarging the pulse thru that high resistance will not really stress the DUT enough.

author: fcb
author_rank: Super Contributor
timestamp: January 02, 2023, 01:56:36 pm
content: Feedback allows you to:1. accuratley set the output voltage2. know where you are in the charging cycle3. use this to detect breakovers in your DUTLOPT - "line output transformer" (CRT monitor/TV part)Pulse discharge network for contact discharge testing is specified in the various standards as is tip design etc.. You want to try and get close to this as it will mean that any testing you do will put you ahead of the game when it comes to testing in a proper (as in $$$) EMC lab.As for FET protection, you will obviously need to allow the transformer primary to fly fairly high, so you could protect this with anything from a transzorb, zener, RC network or even a some sort of pumped-clamp rail.

author: EggertEnjoyer123
author_rank: Frequent Contributor
timestamp: January 02, 2023, 06:37:36 pm
content: Could consider switching the polarity of the rectifier diode.If it is the wrong way it won't work, because the device operates similar to flyback switching supplies, and those require the diode to be the right way to allow the magnetic field to build up.Also make sure it is rated for a high voltage (probably at least 20kV)

author: floobydust
author_rank: Super Contributor
timestamp: January 02, 2023, 06:38:10 pm
content: Quote from: newbadboy on January 02, 2023, 10:00:40 amI think you have the wrong transformer, based on the one picture. Where's it from, did you pot it into the enclosure?I know those as used for igniters in burners and furnaces, the core is solenoid-style. They are driven by capacitive discharge, say 100-150VDC 1uF. So I would not expect much output at low voltage. Also, it (pri+sec) should be phased correctly for a flyback, you might have one winding that needs to be flipped.Instead I think you want an EC core like used in these "15kV generator" kits:https://www.eevblog.com/forum/projects/high-frequency-dc-high-voltage-arc-ignition-generator-inverter-boost-step-up/I've used them for an ESD gun power supply, ran it into a voltage multiplier because I go to 16kV.The main disadvantage is they have no potting or encapsulation for the HV secondary, they are a pretty cheap transformer. You can rewind the primary to whatever you need.

author: joeqsmith
author_rank: Super Contributor
timestamp: January 02, 2023, 07:18:22 pm
content: Quote from: newbadboy on January 02, 2023, 08:50:27 amHow are you measuring it? Consider at 10kV, a 10M load will place a 1mA load on it. Are you sure your not loading it down?For the relay, make sure you understand the datasheet. You may look at a 20kV mechanical that shows it's good for 10A and call it good. You may find the contacts weld short at 10mA when attempting to switch an active load.

author: newbadboy
author_rank: Regular Contributor
timestamp: January 03, 2023, 07:48:46 am
content: Quote from: floobydust on January 02, 2023, 06:38:10 pmThis is the transformer i'm using.https://www.ebay.com/itm/134064910696?_trkparms=amclksrc%3DITM%26aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D244574%26meid%3D0855bf3b520643a2a62b29fca3bcac96%26pid%3D101195%26rk%3D2%26rkt%3D12%26sd%3D313633299561%26itm%3D134064910696%26pmt%3D1%26noa%3D0%26pg%3D2047675%26algv%3DSimplAMLv11WebTrimmedV3MskuWithRevOptLambda90KnnRecallV5ItemNrtInQuery%26brand%3DUnbranded&_trksid=p2047675.c101195.m1851&amdata=cksum%3A1340649106960855bf3b520643a2a62b29fca3bcac96%7Cenc%3AAQAHAAABMKiaD1Uzs5a%252BlLni4j01gco3Hi1A1G%252FJp7lUiWA%252BGKLThP9zrKltERCn1ZKl60m9FvPIet6vCASiGirvoRckl9LTINsIOqDPpMx7R8CdGCpSZSfiB84cT6ndKhgs%252BeMJm2BxjxbzNIkwVNOjUY8XjeNUS2VNR98gpztcgPeTcs5hbA%252BoRF%252B7eQothAeO0Yd6yB3Yxtb0qpQDIl9KhjsSy2iRJ9Pp6%252BHEJ%252BpC3xc%252BG1dEv7dQnMtwhWpLGcJvWmWzppjbU1ym0b8d%252BgsUwQ3A2LxTm5T8U%252F2pRxdtENA4nJAneuPBHaz2Bxi1sn%252FESx%252Fz7ktzCO0tOhsJbbPunGnFgKTjeTtEDjgvuaZPKDK%252BL2tukcMeyCw958kVUJqRb74dlgOpdcrEf0efcv3JyH%252BHToc%253D%7Campid%3APL_CLK%7Cclp%3A2047675And hers is one guy using the exact same with success

author: newbadboy
author_rank: Regular Contributor
timestamp: January 03, 2023, 01:49:21 pm
content: Full schematic

author: newbadboy
author_rank: Regular Contributor
timestamp: January 03, 2023, 02:23:20 pm
content: Quote from: joeqsmith on January 02, 2023, 07:18:22 pmwith a regular DMM. Fluke 179

author: Swainster
author_rank: Frequent Contributor
timestamp: January 03, 2023, 02:43:05 pm
content: Ouch, I would not measure the output of a high voltage generator with a DMM. If you are lucky, the DMM will just clamp the output. If you are unlucky, the meter will be toast. You need a high voltage multimeter probe, which is basically a big voltage divider. A common type has a 1000:1 ratio with a 1GOhm input impedance. If your HV source is very low current (e.g. 10s of microamps) then you could improvise a divider with a string of high voltage resistors in a tube - I've use a biro tube at a pinch, when some bugger has walked off with my HV probe.Also, D2 in your schematic will clamp the flyback voltage. You need to get rid of it and spec your transistor to withstand the resulting voltage spikes.

author: newbadboy
author_rank: Regular Contributor
timestamp: January 03, 2023, 03:03:10 pm
content: no worries regarding the dmm. I had set the prim voltage as low as possible.I have orderad a HV diffprobe for my scope. Have not recieved it yet.I considered D2 to protect the transistor but yea, i guess it clamps

author: EggertEnjoyer123
author_rank: Frequent Contributor
timestamp: January 03, 2023, 07:36:13 pm
content: Quote from: newbadboy on January 03, 2023, 02:23:20 pmSeems like an easy way to kill an expensive multimeter.Either buy a high voltage probe, or make your own by soldering 99 10M resistors together. Make sure the resistors are large enough, otherwise they might arc over internally.

author: TurboTom
author_rank: Super Contributor
timestamp: January 04, 2023, 01:09:43 pm
content: As a paid job, I made a pretty neat continuous duty HV ignition device with one of these chinese coils. You cannot use a clamping diode on flyback topology converters since they will just short out the flyback pulse and keep the magnetic energy in the core from collapsing quickly. As a consequence, you need to lower the excitation frequency to a point where it becomes audible. It's better to use a resonance capacitor.To find the "sweet spot", I placed the resonance capacitor (iirc, it was about 10nF) in parallel to the primary of the transformer and used a beefy mosfet (400V / 10A), driven by a variable frequency / duty cycle generator in order to find the best combination of these parameters for output power vs. dissipation (required for continuous duty operation). In order to cope with a wide variety of loads (i.e. longer / shorter spark gap, varying conductivity due to the presence of ionized gas -- flame, moisture or operation at different ambient pressure...), the best approach was to supply the exciter by a current source. Since it was a contract job, I cannot publish any schematics, but the information may help a little anyway.I've had in mind to make an ESD tester as well but mine would be triggered via a small hydrogen thyratron, with its output fed into an air core transformer to step up the voltage a little and to be able to reverse polarity, followed by an optimized L/C pulse forming network. But as with many of my projects, currently the components are stored in boxes and it's waiting until I've got the time on my hands to finish it... The nice feature of these thyratrons is that they switch high voltages within nanoseconds and will withstand pulse currents of hundreds of amps and they permit repetition rates of at least a few kilohertz. Evil stuff.... And they can be found for quite little money once in a while. One such device suitable for the job would be the Perkin Elmer HY-2 / JAN 7621.

author: newbadboy
author_rank: Regular Contributor
timestamp: January 04, 2023, 01:40:35 pm
content: Yes, thx for info. I didn't really understand the function of flyback and that the diode would clamp it

author: TurboTom
author_rank: Super Contributor
timestamp: January 04, 2023, 04:08:21 pm
content: I'm aware these electromagnetic interactions may be confusing. I recommend to watchDave's tutorial on back-EMF. At round about 12:30 he shows what the diode does and how the flyback voltage looks like without the diode -- which may obviously be high enough to destroy the switching transistor.Since you don't want to dissipate the energy stored in the magnetic field of the high voltage transformer but transfer it to the secondary instead, you don't put a diode antiparallel to the primary coil but rather a capacitor. The energy of the flyback impulse will be transferred to the capacitor (which forms a resonant circuit with the primary of the transformer) and will become (at least partially) available to the secondary during the damped oscillation. But obviously, this arrangement will need some tweaking and optimization.I hope this clarifies the situation a little.

author: joeqsmith
author_rank: Super Contributor
timestamp: January 04, 2023, 06:29:34 pm
content: Quote from: newbadboy on January 03, 2023, 07:48:46 amSadly, he never shows the waveforms from it.Quote from: newbadboy on January 03, 2023, 03:03:10 pmI suspect that meter will present too much of a load. Diffprobe may also be to low impedance.Quote from: TurboTom on January 04, 2023, 01:09:43 pmIt will be interesting to see the output from their gun as I don't believe a simple RC network is going to work out.

author: newbadboy
author_rank: Regular Contributor
timestamp: January 05, 2023, 06:43:00 pm
content: Quote from: TurboTom on January 04, 2023, 04:08:21 pmGreat. ill check his video. THX!!

author: newbadboy
author_rank: Regular Contributor
timestamp: February 06, 2023, 07:41:53 am
content: Here are the first HV measuerments. Main issue at the moment is that the rectified voltage over the cap is less then 500Vdc even though the output from transformer is several kVAre the HV spikes from the transformer so short that it will not charge the cap enough, is my diffprobe loading the cap node to much or what?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 06, 2023, 10:59:05 am
content: I...wait.I think we all missed this in passing:Quote from: newbadboy on January 02, 2023, 10:00:40 amAnd the schematic could use better clarity (readable resolution, showing transformer wiring).By this,do you actually mean there is a diode shunting the very flyback you were looking to draw from the transformer?Where are the scope waveforms probed at? What does the layout look like?What is Q2? D2? Transformer? Why 68k in series with HV rectifier? Is there no HV sense, how can you tell you've reached the end point? Surely you weren't just going to pulse it until it feels right?Is the transformer phased correctly?Speaking of, were you planning on reversible polarity? Because that needs to reverse not just the diode but the transformer as well.FYI, think of this as a switching voltage regulator first and foremost. Then everything required comes naturally: current limiting, PWM and/or frequency control, voltage regulation, phasing, topology. Giving it some random pulses 100% blind is not a plan for success!Tim

author: newbadboy
author_rank: Regular Contributor
timestamp: February 06, 2023, 12:19:59 pm
content: Quote from: T3sl4co1l on February 06, 2023, 10:59:05 am

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 06, 2023, 02:46:45 pm
content: If you could add [ /quote ] ... [ quote ] sections to your text that would help greatly (or use the WYSIWYG editor to the same effect).Tim

author: EggertEnjoyer123
author_rank: Frequent Contributor
timestamp: February 07, 2023, 08:34:14 pm
content: You should be able to get more power if you solder a capacitor in place of D2

author: floobydust
author_rank: Super Contributor
timestamp: February 07, 2023, 09:55:03 pm
content: OP I noticed the digital POTMCP4011is only rated to 5.5V and will get damaged if the Vreg U5 is set beyond say 7V output.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 08, 2023, 01:17:35 am
content: Easier anyway to do that with an inverting-type regulator (can use an op-amp to perform this on a 3-terminal / follower type), with a PWMDAC (run PWM from a pin into an RC filter). Bandwidth wouldn't seem too important here, which is otherwise the main downside of such method.Admittedly, inverting-type regulators are, eh maybe a bit less common? They appear often enough among LDOs as such, I guess.Oh, speaking of, AZ2185 (if I'm reading those pixels correctly?) isn't, it's an old fashioned HDO, but no one differentiates them anymore, they're all classed under "LDO" now, go figure? So you're losing a couple volts there (in maximum range) right from the start.A buck regulator could also be used, which always(?) have inverting-type feedback inputs [if they have it at all], so can easily be controlled by DAC.On digital pots, just generally:It seems like people use them much more often than needed. I suppose it's tempting to just replace a resistor/rheostat/pot with one and go, but there's almost certainly a better way to do it, except for specific applications where they are the best option. Mostly stuff like volume control, i.e. where you're doing multiplication (Vout = Vin * wiper% / 100%), so a mere control voltage won't do. And in that case, it may be just as well to take the more general case (multiplying DAC, i.e. Vin to VREF) rather than the more specialized "digital pot". Even more specialized might be something like a variable filter or oscillator; but those are even easier* to solve wholly in digital (ADC-DSP-DAC); the pure-analog solutions are basically obsolete.*For certain values of "even", and "easy".But really, that's all completely avoided by just treating the power supply section here as a power supply, so the voltage control, current limiting, fault protection, and PWM output all manifest as the necessary aspects of the system. Depending on which PIC that is (I don't know the numbers, I just know a few bits about the families generally), you might even get some of that logic for free, like the ones with SMPS helper hardware integrated, or use CCL to the same end. Peak current mode control is very easy to do with these MCUs. (I'm more familiar with AVR, among which the AVR-Dx have such features available, and I have indeed used them as such.)Tim

author: newbadboy
author_rank: Regular Contributor
timestamp: February 09, 2023, 09:27:53 am
content: Quote from: floobydust on February 07, 2023, 09:55:03 pmU1 is powered by U4 which is fixed 5V.U1 is only controlling U5

author: newbadboy
author_rank: Regular Contributor
timestamp: February 09, 2023, 09:36:11 am
content: Yes it is AZ2185.It doesn't really matter loosing a couple of volts. It outputs more then enough to get high voltage on the coils secondary. Ill need around 3-5V primary to get 7-8kV secondary

author: newbadboy
author_rank: Regular Contributor
timestamp: February 09, 2023, 09:38:45 am
content: I have experimented with a few snubbers and also single caps, and they do smoothen out the oscillation but it does not effect the rectified output level.I have ordered a much faster rectifier diode, o hope it will give better/ higher rectified output voltage

author: EggertEnjoyer123
author_rank: Frequent Contributor
timestamp: February 10, 2023, 09:39:00 am
content: You could consider chaining multiple UF4007s together in series to make a fast high voltage diode.

author: tooki
author_rank: Super Contributor
timestamp: February 10, 2023, 11:59:16 am
content: Quote from: newbadboy on January 03, 2023, 01:49:21 pmCould you post areadableschematic? That image is simply too low resolution.

author: newbadboy
author_rank: Regular Contributor
timestamp: April 28, 2023, 07:46:20 pm
content: I have progressed slow and now i have reached a working low voltage and high voltage solution.My biggest issue is that the pickering hv relay is not really working at all. There are so big contact bounces that the Pic controller and everything crashes. Even my computer screen restarts on every shot.What could i use as switching component?

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 29, 2023, 04:16:09 am
content: Sounds like it's workingTim

author: newbadboy
author_rank: Regular Contributor
timestamp: April 29, 2023, 06:57:49 am
content: Haha shut up. Wel Yes it works in that aspect maybe 😃😃

author: T3sl4co1l
author_rank: Super Contributor
timestamp: April 29, 2023, 09:16:31 am
content: Well, isolate* everything, get that EMI under control for now. Put the high voltage section (spark discharge included) into a box. Filter wires through the box where possible. While you're at it, begin to test the waveform -- make the discharge fire into a termination resistor and attenuator, and scope it. With everything against ground plane and under shields, common mode should go away and you can work in peace, for the moment at least.*In the sense of separation; lack of communication; shielding!Note that the characteristic double-peaked waveform will have to wait, as that depends on the connecting (ground) cable; concentrate on the leading edge rise time and overall exponential decay.Then you can try and invert the shield so it goes around the PIC instead, and, maybe your first project is to fix your computer's ESD sensitivity?(Or that goes away in the course of cleaning up the waveform -- perhaps the edge is too fast or tall right now.)Tim

author: newbadboy
author_rank: Regular Contributor
timestamp: April 29, 2023, 02:42:57 pm
content: Well you are right of course regarding the shielding. I will try with some box or metal shield.What i noticed was that this big RF disturbance in only present when i have the cables of my HV diffprobe to measure the tip of the gun. I guess it becomes a perfect antenna.What im more worried about is the actuall contact bounces. I can hear how the sparks sound inside the relay when it switches and i think it's wierd because it should be able to handle 7.5 kv and the only load is the diffprobe.

author: newbadboy
author_rank: Regular Contributor
timestamp: April 30, 2023, 11:06:16 pm
content: This is how far i got this time. I will get a proper vacuum relay later on.https://youtu.be/QBnDhUDD88s

author: joeqsmith
author_rank: Super Contributor
timestamp: May 02, 2023, 01:09:44 pm
content: Looks like you made some good progress. When I designed my gun, I wanted something that would trigger no faster than a half second per pulse. In your case, it appears you are charging the output with a 68k ohm. I suggest removing the relay or just leaving it on and have the output drive a fixed air gap that is small enough to arc over. Now, when you turn it on, set the 68k to something that gets you close to the max frequency you want. Say you set it to oscillate at 1Hz, you will only see the one pulse when the relay bounces.There was a young man who started a thread about oscillators where I posted a few examples.https://www.eevblog.com/forum/projects/my-own-original-oscillator/msg2533200/#msg2533200

author: newbadboy
author_rank: Regular Contributor
timestamp: May 03, 2023, 03:02:10 pm
content: Actually the schematic is a bit old. Im charging the cap directly from that transformer and rectifier

author: joeqsmith
author_rank: Super Contributor
timestamp: May 03, 2023, 03:26:08 pm
content: What you are seeing makes sense. Was your plan to run the boost until the cap is charged, then turn it off before the discharge?

author: newbadboy
author_rank: Regular Contributor
timestamp: May 03, 2023, 05:31:35 pm
content: Exactly. Chage it some time, shut down the boost. Discharge thru the relay

author: joeqsmith
author_rank: Super Contributor
timestamp: May 03, 2023, 06:09:07 pm
content: During your video, I assume you are leaving the boost converter on. Have you tied it with the supply turned off yet, or is the problem with the digital resetting?

author: newbadboy
author_rank: Regular Contributor
timestamp: May 03, 2023, 07:18:19 pm
content: In the video the relay is on all the time and I enable the boost on and of. So there are no contact bounces since the relay is not moving. If i would have the relay toggling the whole esd gun goes crazy. Even my computer screen restarts

author: newbadboy
author_rank: Regular Contributor
timestamp: August 31, 2023, 12:12:06 pm
content: I have now good results with the new vacuum relay and no issue with contact bounce.My final issue to solve is that the boost converter module is use has a ON threshold of 5.5V and then the output is around 7kv.I would lika to find a similar module that has lower on voltage and lower start output voltage.Any ideas on what there is out there?