Reminds me of Big Clive's "Gabriel electrode" for a Jacob's ladder. I love your use of plumbing fittings... my lathe is no stranger to such things.... never thought that I could use them for electronics.... nice!
Pleased to report that I've just completed a nitrogen laser based on your 20-cm. design, adapted to suit materials on hand, and am successfully pumping Rhodamine 6G to threshold. Some 25 years ago, a bought .015" copper clad board, intending to build the SciAm laser, but I couldn't bring myself to deal with etching something that large and then having to dispose of the chemicals. Other N2 lasers I've seen were just too kludgy; I wasn't willing to make the tabletop part of my laser. Thanks for your exceptionally clean, workable, and high-powered design. I was able to lase R6G even before installing an end mirror. Am fighting the urge to buy a power sensor. My wife, BTW, can't understand why anyone would build a device with no practical application. I remind her that some people build model airplanes.
Awesome! I am so glad people are getting use out of this deign. Yeah I built the Sci-Am design (except with doorknob caps) and it worked well, but it was large and involved too much faffing with vacuum pumps for my liking. Well, everyone need a hobby, besides I find functioning things more exciting than models of functional things!
Pressurized SF6 laser triggered gaps were used on the PBFA II . It's used a fair amount in the accelerator industry. Be careful of (S2F10) generation in an arc; it dissipates quickly though. Awesome work! I love your approach. Just subscribed and look forward to more fun stuff!
Totally cool!!! I used to design a trigger spark gap system as an intern, those things deserve more coverage on youtube :) looking forward to your experiments
One way to get a high voltage PS with a lot of current, is to use a neon sigh xfmr. This is how I charge by giant quarter-shrinking supply. You can get 30mA easily. The HV diodes are small and cheap on ebay. I used three 20kV / 50mA diodes in series for safety. The NST is current-limited, thus one rated at 30mA will be fine with these diodes. A few of the 40kV caps in parallel should work for creating DC. If you use a FWB diode config., then the capacitance can be halved for the same filtering. A variac is a nice option for the NST input. I have used two 12kV NST's in series and got a total output (with variac) of over 39.5kV @ 30mA. I potted these two cores in wax. ...and yes, the NST will make things a bit heavy. I mounted the single NST PS in plexi. with diodes,... all on top. Be aware that the case of the NST is a center-tap.
Hi Les. Thank you for the very informative video. Just one note of caution, if I may. I have a few of those ht inverters and they work reliably up to about 200v, (perfect for nixie tubes, for which reason I got them) after which they have a tendency to become unstable. The ferrite core becomes quite hot as do the 10uF smoothing which btw are rated at only 400v. I started to build one of your triggers using a car ignition coil instead :). Always looking forward for your next video!
Thanks! there are two version of these, one has a simple rectified output (blown up a few of these!), and the other has a voltage doubler arrangement, for a higher voltage output. Also, if you ground the output of these it shorts the supply as well, so you have to leave them floating. Sure, thay are not the best, but they are so cheap.
Hi Les, I just received the trigger transformer in the video. I needed a trigger supply like yours in the schematic...I intend to build it with some changes: Referring to your schema (top to bottom): 1) I will use a 555 astable for an adjustable pulse width. The 555 triggers on the FALLING edge of the input and puts out a positive pulse. 2) I have had it!! with SCR latchup! I will use an isolated IGBT, (or HV MOSFET) with snubber. 3) For the one-shot...another 555 (astable) for the manual pulse(s), eliminating the 7414 IC. In astable mode the 555's positive out pulse has hysteresis...the trigger button can be repeatedly pressed, but has no effect during the output. ...so it looks like just a dual 555 (the 556). BTW, the output of the 555 (pin 3) is actually a half-bridge configuration that very easily sinks and SOURCES over 200mA. ...and that great triggered spark gap (optically, if enough ionization can be had with powerful 250nm LED's). THANKS FOR THE INSPIRING VIDEO!!! Your other's are also OUTSTANDING!
Cool. for latch the latch up issue, I have started using neon lamps to commutate the trigger pulse to the SCR, and this seems to fix it, but yeah, it is a giant pain. There are better methods of triggering it has to be said! I ordered a deep UV LED a while ago to try this, but other projects have gotten in the way!
Hi Les, I have found plenty 250nm (UV-C) LEDs on ebay, including the multi-watt star-type and a 'light bulb' made of over 100 250nm LEDs. I also found 7mm lenses (~$0.69 ea). All this seems to have become available after covid...I guess for anti-bacterial and sterilization techniques...I could never find them before! I plan to make a 'ring' of these around the gap, each with a focusing lens to concentrate the light at the gap in the center of the ring. As you probably know, you can't just place a large lens over multiple lights...you will just get a bunch of focused disjoint points of light. If you place a lens on each LED, you get some overlap though not much. I think a ring of LEDs and a lens for each will focus each LED to the single desired gap point.@@LesLaboratory
hi Les good work indeed! this has just made my day! i was looking at ways to manually fire my marx generator without using mosfets etc. good job! keep up the good work!! ;-)
Thanks for the video. After examining a few different circuits for electrically triggered spark gaps, one concern I have is backfeeding the trigger circuit with the high power side. What stops or protects the current from jumping backup up the electrode of the spark plug and into your trigger circuit please?
Hi Les, looking at your 'trigger generator', especially the ZVS driver (I have about ten of these, which I have used for various applications), They don't seem to have a common ground...input to output...I see you have used the "+" and "-" I/O to get 500 VDC out. I use this config in most apps. I was wondering if you have had any grounding issues with the HV 'Gnd" and the 5V Gnd? Have you measured the voltage across the two 'Gnds'? I get some fairly hige voltages...not 0v. I plan to use a high power MOSFET (1000v @46A) as my trigger switch ..or maybe an IGBT, The reason I ask is that I am having trouble witch SCR latchup. Also, the maximum FET gate voltage/source is +/- 20v. But am afraid to do so with unknown ground relationshps. On your schematic, you seem to use the gnd's as if they are directly connected...and your ground symbles are the same in the schematics. Are they internally wired together in your trigger generator? From other similar projects, a seperate 9v batt works fine for isolation in the MOSFET gate/gnd control. I just received (ebay) an isolated dc dc xfmr that should work....would like to know your thoughts on this. THANKS MUCH!!!
On the topic of high-voltage, I'd love to see a video on spiral line vector-inversion transformers, if you've ever played around with those, or even if you haven't. I've seen them used in the laser community here and there and you seem to be skilled in the art. Another topic might be a raspberry-pi or microcontroller-based phase-OTDR for seismic sensing with say 9/125 SM fiber. Awesome channel, thanks for sharing this knowledge.
Try using a subminature rectifier tube with a blown filament. The 5xx series by apalla are particularly good, switch on in less than 0.1nS. Used them in place of kn6 krytron tubes. No biasing required, just give a 1kv trigger pulse and it fires up to about 14kv.
Please excuse my ignorance but how short of a pulse width is this subminiature rectifier tube capable of? Does it turn off after a pulse is fired? I’m looking for a method of firing a very fast short duration pulse to a 1kv high voltage transformer primary for generating radiant energy bursts.
Awesome! I was actually looking at designing my own triggered spark gap and it was great to see your work. So what's the breakdown voltage of the gap if not triggered? Was there any sort of process around deciding how large of a spark/what voltage you'd use to trigger the gap? Just curious how you arrived at your design, or whether it was just a random guess (Which is what I'd have been doing otherwise). My thought for a triggered spark gap was something like a xenon flash lamp, where there's no direct connection to the gap, the high voltage outside the tube/gap inducing a breakdown. I was wondering how much power a tube of a given size with X wall thickness could handle (And at what pressure it should run at), since I'm looking at switching thousands of joules. My intent was to switch a few KV at a much higher current, so there may not be that much overlap in our requirements.
Sorry for the late reply: The gap was designed iteratively. I already know the static gap at x pressure would break down at y voltage, so the next logical step was to deal with triggering. To be honest, I have probably over-engineered the trigger, only a small number of ions is required to initiate the breakdow at its holdoff voltage. I don't think that a Xenon tube would make a very good gap, as they are engineered to dissipate as much energy as possible as light.
Hi Les, PLEASE tell me what SCR you are using in the trigger transformer circuit shown in your schematic. I have tried several...some latch-up at 100us, and some don't seem to conduct enough. I have one rather large one that works properly. I have used the RC-differentatior and a 555 for firing...both seem to work equally. About the ZVS driver: I have gone through several of these...some exploaded! I found the problem: it is the two10uF electrolytic caps near the output rail...they are only rated at 400v, which is often exceeded in operation. I ordered a bag of 10uF 450v lytic's of the same physical size. After replacing them, ALL problems dissappeared! I now consider this a great ZVS HV device. I can't tell from the video, but did you use the + and - connections for your 500v source. This works well, but MANY of these drivers come with only one 'side' connected making the dual polarity impossible. I always make certain that the ebay seller sends me the types with BOTH caps installed. IIRC, my giant N2 laser has the largest doorknob caps I have ever seen. The channel has a vacuum pump, bandsaw blade electrodes, and looks to be nearly a meter in length and has an end mirror. It was built in the '70's. EVERYTHING is adjustable...the thyratron even has seperate variacs for precise control of the filiment and reservoir...safety shutoffs for everything. I think it was a prototype. ...seen all but a couple of your videos so far....just discovered them! --dAle
I am using a 30TPS08PBF SCR in the circuit. Yeah latch-up can be an issue. I started using Neon lamps between the moc3020 and the Gate in later versions of this circuit that prevents this happening. Yeah, some of those ZVS drivers can be flakey, and yes I always get the ones with + 0 - outputs. I have never had one explode, but I have ad caps fail. Nice! I bet the output is well over a Megawatt per pulse, maybe even a couple. they used bandsaw blades to ensure the gas was fully ionized and produce a homogeneous discharge along the length when they fired I believe. My first N2 Laser used copper sheet electrodes, and was low pressure, but unlike the Sci-Am design, I used doorknob caps in it. Awesome! There are some interesting project in the works!
Having terminated fiber optic cables for telecommunication use, my knee-jerk reaction to that fiber interface was about what you'd expect. (😱) Thinking harder about it though, that makes total sense, and it's a great hack. 10 Hz or 100 Hz (or perhaps even 1000 Hz) doesn't require the fiber to have a perfect face to work, as a 10+ GB connection does. I shall have to keep this in mind for use with my function generator. Thanks! 👍️
I don't know if it's still available, but there used to be a range of FO cable that was simply 1mm dia. You just cut it with a knife and used push on connectors. It was used in audio systems, so several 10'd of kHz . I think Maplin used to sell the stuff, Looked very much like the cables used in the lighting display world that you see on ebay. Andy
TOSLINK uses cheap plastic fiber and can get 3Mbps. I've seen several tesla coils that use a similar fiber for the interruptor/control communication but with different connectors. I had a project where I needed an isolated serial connection, so I cut up some toslink cables to get the fiber. I'm not doing any polishing of the ends, and I don't even have optics to help get the light into or out of the fiber. For RX, I have a PIN diode, a fast-ish opamp as a TIA, and a comparator. The TX side is just a red LED, so I can easily build that into more projects and reuse my receiver. 115,200 baud goes through just fine, and it's the bandwidth of the TIA that's keeping me from going faster.
What SCR did you use? I am trying for weeks now to get the circuit to run. I get my 100µS pulse out of my 74hc14. This signal goes (buffered) into the moc3020 but the Triac doesn't switch. I am currently using a BT151-650R.
Fascinating! The original DIY nitrogen LASER IIRC was in Scientific American in the 1970's and used a plunger/solenoid directly onto one side of the PCB that formed the capacitor. Two questions: First can you initiate the spark with UV light? The work function of zinc (in your brass) is about 3.7ev and the copper is 5.?ev. The new UVC LEDs should get some electrons flying off the surface. And second, why not use an automotive coil-on-plug with your spark plug and eliminate the HV wiring plus need to protect instruments?
automotive coils way too slow...you have to have a super sharp edge on the trigger pulse the trigatron sees- a series spark gap rather than a direct connection to the trigger electrode from the generator helps some too, but no iron here : )
another great video. Have you ever thought about doing a CO2 laser type recharge video? The occasional Synrad RF lasers come on the market but often suggest a need for a recharge. Thanks Doug
Thanks! Yeah, I have been looking for a suitable candidate for some time. There were some a while ago with what looked like demountable optics, but I missed it!
nice...rotary spark gaps, trigatrons, laser triggered spark gaps, hockey pucks all delicious- bout 20 years ago made a from scratch a copper chloride laser that incorporated my version of a trigatron with ceramic insulator- the electronics was the most difficult-the false triggers and such-but got it going fantastic dumping 2 pulses separated by 50ns resolution out to ms delay between em running at hundreds of hz----do not let anyone tell you different, trigatrons are the best !!...serviceable too !!...and jitter, what jitter ??...the cucl i could by pulse separation alone ( by memory 50 us separation ) get it lo lase only the yellow- super reliable and steady like a hene to perception.......maybe Less will do a 337nm triggered spark gap, wanted to do that someday but too busy with other stuff
Very nice! I would love to have a crack at a Cu Vapor laser (any metal vapor for that matter! For sure, spark gaps are really under-rated, though there are sill companies that produce them (if you ave a big enough wallet!) From a cost saving perspective, it's a no rainer to roll your own park gap. It's either that or $$$ for solid state or random H2 Thyratrons if you are lucky enough to find them!
Hi Les, I still don't understand how your reconfigured charge distribution replacing the spark gap with the capacitor bank works. The new layout results in your doorkobs aligned in series with the foil capacitor and with the 120k resistor shunting their junction to earth. I undetstand that the trigger itself is as you rightly say best kept with its negative tied to earth but the reorientation of the doorknob capacitor bank results in a circuit I have never seen referenced before and so far I have found hard to make out the function of. Would very much value your comment. Thanks
Yeah, I should probably do a video on that, it looks like it shouldn't work right? It becomes clearer if when you draw these out, you don't call 0v 'ground' or 'earth' and think of it as floating. Secondly bear in mind that when the spark gap fires, it doesn't close like a switch, but 'rings' or oscillates. this means when the gap fires, 'earth' or 'ground' will swing between -20kV and +20kv. The voltage across the peaker and the channel will do the same.
@@LesLaboratory Hi again and thanks for your reply. So when you refer to "ground reference" (14,01) where exactly do you mean. A circuit diagram of the altered route would be very helpful and might make things more easy to understand. Keep up the feeds. You have a great channel.
Hi Les! Another fascinating and enlightening video, thank you so much. I have two questions if you have a spare nanosecond. You have not included any resistance on the HV output, why is this? Also are the dump capacitors a special variety? Many thanks, I may need to build a trigger which fires when a drop of current between two consumable electrode occurs. I never thought a local spark would suffice to get a conductive path going. Super info!
*"You have not included any resistance on the HV output, why is this?"* A resistor on the output is just to limit the output current. There is no need you don't need to protect any capacitors from discharging too fast (no Capacitors on secondary side of the transformer). *"Also are the dump capacitors a special variety?"* The Capacitors from the pulse generator are MKP capacitors often used in the Audio space. The Capacitors from the Laser are Doorknob capacitors (for lower ESR).
@@GermanMythbuster I didn't know the output resistor had the function of protecting the capacitors, but now that you say it, it makes good sense! I assumed they just protected the HV transformer from 'short circuit' with the uncontrolled discharge and so possibly over heating the HV transformer on high repetition rate. Every day is a school day. Thanks
I saw 4 resistors at 8:46 near the yellow caps, are they in series to limit SCR current? If not I also wonder if current limiting in this case is required.
Excellent work👌👌👌👌👍 - it makes for a more controllable practical lab unit - I wonder if you had a holographic system and photo sensitive resin if you could build some 3d sculptures was a smallish unit ? 🤔
You mean something along the lines of photo-polymerization with the Nitrogen Laser? I guess so, but there are far better Lasers for this kind of work! I am currently repairing a Q-Switched 355nm UV DPSS laser that woudl be eminently more suitable for such applications.
I like your spark gap design. But I also have a question: The power part of the trigger curcuit, isn't that the interieur of a CDI in the end? I mean, what you are doing is triggering a spark plug... Please don't get this wrong, I am not criticizing your curcuit, I like it. But when a friend showed it to me, I thought, wait a moment, I know this from somewhere. So I was wondering if you could replace that part with the CDI module, you can buy, or if you have to be able to customize the power part of the curcuit.
Sure, fundamentally they are the same. The resason I built my own, is I wanted the voltage and storage capacitor to match the specification in the datasheet for the Trigger transformer, and I wanted it opto coupled. Compared with Ignition coils, the discharge from a trigger transformer is very fast and very short, a requirement if you want to avoid Jitter and turn on delays.
At ~ timestamp 5:19 you mention a "previous video" where you made an earlier SG project. I have searched and searched and can't find it. an you direct me to it?? Thanks much!
They are in the description: Original Nitrogen Laser video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-pCnXftuJ9Zo.html Nitrogen Laser teardown: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-AyN1o_3XaTw.html Laser capacitors: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-8wUxYVe98Uo.html Cheers!
I see that in the High Voltage trigger, you are using an optoisolated TRIAC. Is there any reasin a simple opto-transister won't work? Thanks much, --dAlE
I am sure you could, but you would need one with a high voltage rating, and a reverse recovery diode no doubt. The opto triac is commonly used in most application notes and schematics I have come across, so why not use a known working scheme.
Since you're dialing in this apparatus so that you can systematically tune the whole system, consider that the Earth is moving ~1000mph on its axis, revolving around the Sun ~66,600mph, and the Sun is revolving around the galaxy ~580,000mph. The galaxy too is moving. Our science experiments do not impinge the same point in space in a universal frame. We're traversing this corkscrewing pattern -- seems still, it isn't. Chemistry and electromagnetism work at this velocity, but I think we miss out on some of the "fabric" effects due to our assumption we're not moving. Granted, we're not moving at the speed of light like your lasers but I wonder if you can identify some kind of spatial anisotropy that correlates to this motion, and say lunar tidal forces. I know Michelson and Morley tried that with an interferometer, but I'm thinking in the population inversion itself, or the operational properties of the spark gap. Another way to put it is that I hypothesize that your Nitrogen laser and your spark gap function better in specific orientations as a function of your position on Earth and the alignment of the channel/gap with its actual motion in a larger frame of reference. The idea is that if the light impinges the same location in space, or even only that the energy of the laser is concentrated in a smaller linear volume of space (since it's faster than our motion), that the "fabric" effects of the Universe start to shake out, or if nothing else, you can do more effective work with less laser power input to the system.
It seemed like the laser sometimes fired twice on a single button press though, is that just a tuning issue to dial in the laser channel spacing/gas pressure/current?
I need to use a larger cap in the de-bounce circuit for the trigger. To be honest, the button is just a convenience for testing, for real work I use the optical trigger input.
Can you do a video on a circuit to start up an arc lamp?? I have some CW xenon laser lamps and I can get a spark through them, but I can't transfer to the low voltage DC (180V@20A) quickly enough to keep it lit. It's for a CW NdYAG build and there's so little on the web 😵💫 love your videos!
I was going to comment on this too. I'm sure it's just an oversight. If the NPN transistor was instead PNP (and collector and emitter flipped) it could work, but I'm pretty sure he just meant to draw a CE inverter and put in a buffer instead.
It is a question of how much UV to trigger the gap. I am not sure a UV LED would work, but the UV flash from another spark triggering a gap as indeed demonstrated historically. This effect is used in Marx generators. The UV from the first gap helps ionize the subsequent gaps.
@@rickmally5777 yeah interesting to watch. There are other forces at play there as well I think. Seemingly it was demonstrated that a discharge can initiate another 10's of km away, well beyond the reach of UV. I feel there is still a lot of research to be done in the HV, but it seems not be be very popular lately! Lightning also generates antimatter. It's a very cool topic indeed!
You definitely comes out with very educational and interesting videos. Thank you. I have a question and probably dumb too, has to do with a nitrogen laser. I know they had done this experiment, but wondering is possibility to achieve it in a low scale or medium scale.. my question is, if you have a spark gap like the way u have and then shot a laser between those gaps would extend its spark length?
Thanks! I have tried this as a half hearted attempt, and observed no difference. That sid choice of materials may well affect the experiment. I will give it a proper try at some point.
SIR : "YD-350" LOOKS IDENTICAL TO THE *IGNITION COIL USED IN MANY PROPANE HEATERS in CAMPERS + MOTORHOMES ...THEY RUN ON Q2 volts and use a SPARK PLUG WIRE TO IGNITION ELECTRODE
Of the Nitrogen laser Laser? I have measured this at 223 microjoules per pulse in around 1 nanosecond (279kW or there abouts) the average power at 25hz is about 5.5 milliwatts.
11:15 - What values did you use for your differentiator? *(ANSWER: 22 nF and 4700 Ω)* 10K and 1nF? (Periode: 100 µSek ) In my mind with those values the output of the Schmitt-Trigger is
@@LesLaboratory Thanks bud 😊 I always get Inspired by your videos, I really like your work. Its always a huge motivation to work on my projects if I see a video of yours. Soldering station already turned on 😂😂
@@GermanMythbuster Thanks! I like producing them! In answer to the other half of your question regarding differentiators, there is a tutorial here: www.electronics-tutorials.ws/rc/rc-differentiator.html, Im sure the hysteresis data his available as well in the 74HC14 datasheet, but honestly I just bread-boarded one up, and measured it with the scope, and tweaked my values.
Maybe. There is a lot of "Theoretical" modelling on UV LED triggered gaps, and an IEEE conference proceeding which is just an abstract (weird). In principle it appears possible, perhaps I will look into it!
@@LesLaboratory I have order one too. UV LED Triggered Spark Gap for Repeatable Nanosecond Pulses Henning, Brian ; Light, Adam talk about using a 280nm LED Gas-filled laser-triggered spark gap O. Frolov, K. Kolacek, V. Bohacek,J. Straus, J. Schmidt, V. Prukne Seem to have done it with a laser Nitrogen can be tricky to ionize a touch of helium might help
