464 Better than GreatScott's Coil Gun? A true story, how-to not do it
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- เผยแพร่เมื่อ 2 ก.ย. 2023
- This is the last re-run of a video (from 2018). In two weeks, I will be back with a new video.
I should have been warned: Some viewers on our summer project were against a gun on the tank. But I did not listen. This video shows what happened and how I was punished.
In Switzerland, every adult man is in the army and has his weapon at home. Maybe this is the physiological reason for my choice. I am not a psychologist; I am an engineer. So let's start with the story about How-to build a rail gun or a coil gun. Or how to not do it...
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If you are interested in how I repaired the power supply: Search for "#228 How does a Linear Power Supply work? (Incl Repair)"
thank you! I always enjoy whatching your videos! what I don't get: why is your repair-video older than the one above where you bricked your powersupply?
@@amtsgedicht I my summer break, I present old videos (it was a viewer's idea).
An armed citizen is a free citizen!
As a Swiss, I would have expected you shooting an apple! Especially after the reference to Steve Jobs :)
*lach*
lol
😂😂😂😂
A valid point. But the nail was not fast enough...
@@AndreasSpiess So.. looking forward to railgun "V2" hehe :)
You can simplify you circuit by connecting the 400 volt supply to a 100 volt cap, placed strategically behind the projectile..
Maybe an innovation: Capacitor guns ;-)
@@AndreasSpiessPlasma Channel did this: Electric Capacitor Revolver
So charmed to know that someone with your training and experience is as reluctant to work around high voltages as I am. I keep telling myself that someday, when simple ideas have sunk in, then only will I progress to more risky projects. My timidity has kept me safe so far. But I know that, even though electricity follows immutable laws, still it is no respecter of persons and does NOT give second chances. Thanks for sharing your coil-gun experience. I think I'll stay with my op amps, tiny DC motors, and LED's for the time being!
A good choice, I think. Let the high-voltage stuff to the trained people.
Unwritten rule number 1 in electronics: Never connect microcontroller pins directly to controlled electronics with a higher voltage than the microcontroller's operating voltage! Galvanic separation! 😂😂
Corollary: Never connect 5V/3.3V microcontroller pins to switch high inductive loads even when they are on the same low voltage supply rail. Don't ask me how I know. Suddenly shutting off the current causes the electromagnetic fields to collapse and induce a high voltage. Even a flyback diode may not switch on quickly enough to quench the spike before it damages low voltage tolerance GPIO pins
2nd Corollary: Never move super powerful magnets near small inductive loads hooked up to sensitive electronics. Brainiac75 did this and I think it killed the brushless DC motors in his powersupply
I would have put a fly back/back emf diode across the coil as well.
But overall a fun project
We learn (or we should) from our mistakes. IGBT and some protection back to the ESP will help, also thicker wire in the coil and a reverse voltage shunt diode across the coil to prevent the large back EMF you are going to generate when the magnetic field collapses.
I agree with your proposals.
When I started my "adventures" with SCRs, we had no ICs yet. Just discrete transistors and passive components. But there were some good data sheets and better yet, application notes - even books. So I kept reading and reading. Somewhere there I found that A term dI/dt was something to take literally. If you let the SCR experience a very high dI/dt, it tended to blow its magic whatever in no time at all. The explanation was that the current was concentrating near the gate and not having time to spread over the whole silicon area. Two solutions -- first the manufacturer of the SCR had to provide some means of spreading the gate wider (at least effectively). The second one was that I, as the user, had to design my gate drive much better. That meant timing and amplitude optimization. The static gate trigger voltage was not good for the desired effect, I needed much more, and that in a controlled seed along with certain resistance. Additionally, It was necessary to consider what happens when I try to end the kickback from the coil. A thyristor does not have infinitely fast recovery either! Much of the time I had to add a second, small value inductance to the anode and a free wheeling diode next to the SCR & small choke combo. So I designed my own gate drivers with a few microseconds rise time. Armed with the good info and god drivers, we eventually used SCRs quite routinely. And one last application used a then new high performance SCR to produce up to 10 000 A pulses (not for coil gun, though).
As you describe: Such a project is more complex than I initially thought. And it needs a lot of experience to work in those topics. I decided to go the other way than you: Avoid it in the future ;-)
@@AndreasSpiess No graphene making for you then! 🤣 As shown here "Making graphene could kill you but we do it anyway!!"
Just wanted to throw in that there is a difference between a coil and a railgun. They work quite differently =)
You are right. I learned it in the meantime
What I learnt from this video:
1) Every Swiss man has a gun, 2) Some Swiss men are noobs, 3) In Switzerland you can be a noob and still own a gun,
4) It's a bad idea to invade Switzerland.
All statements are correct ;-)
Fantastic video about the world of high voltage. I am a 76 year old engineer that got a ham radio license when I was 15 years old and back then EVERYTHING was high voltage. The first transmitter I built had over 400 volts on some of the vacuum tubes. It is a different world. Switched high voltages can also create rather powerful RF pulse that may have been the source of some of your mysterious effects. In the USA, the world of high voltage is at about 50 volts according to the National Electrical Code. That is one reason that telephone and data lines generally run at 48 volts. I have been watching your videos regularly and they are the most informative on You Tube. I hope you can fix your power supply, it appears to have been a very good one.
I was born a bit too late for tubes. They only were in the power stage of my first FT-277 ;-)
It seems easier to build a weapon with a magazine of Chinese 400V capacitors and charge them with 402 V.
Electroboom already did that. The hardest part is making the magazine.
:-))
@@user-jp7tw3sd3xSee the Plasma Channel's electric capacitor revolver
You can use square copper wire (used in windings of big transformers). It's resistance is much smaller and due to the square shape, you can pack the turns more tightly on the bobbin.
I agree. The coil would be come smaller.
That reminds me of when I worked for Kistler Instruments - it wasn't a coil, it was a 'secret' box that had many Kv dropped through it from a bank of PF caps. The aim was to measure the pressure produced on firing...it often would fry the charge amp, (at about £1,000 a 'pop'!) and cable, despite it being many metres away from the pressure sensor! It seemed the EMP was rather strong!
Indeed, an excellent example of "EMP"!
5:00 Everyone knows that at the factory electronic components are filled with "magic smoke", and that's what everything works on. When magic smoke comes out of a component, it stops working :)
Good explanation!
Now you can make a video, how to fix your bench power supply
And then title it video #228 How Does a Linear Power Supply Work? (Incl. Repair)
Exactly ;-)
This was another pleasure to watch.
It also shows that there are many different disciplines in electronics.
These kinds of experiments are not without danger but are fun.
Which reminds me of a tube FM transmitter I once built.
I didn't realize that the field around the coils in the endstage would be a bit more powerful. Soon it smelled like burnt meat and I had to run to the faucet. :)
I am happy that we do no more need tubes for the RF power amplifiers. When I was young, this was the standard (I never worked with them).
Andreas thanks for thé store and it reminds of a story I lived a long time ago, in my first year at the faculty of electrical engineering. This was during a Signals and Systems lecture and the prof was covering stability criteria and started to say “for example if you have a tracking gun… “with that he was interrupted by a growing murmur or sounds of disapproval, however he quickly pivoted his example saying “or .. ehhhh a tracking antenna….” and carried on to teach us about about the location of poles and zeros ….
Indeed, TH-cam downgraded the monetization of this video because of the word "gun". So nothing new after so many years ;-)
The thyristor actually produces a voltages pulse on the gate when current flows from anode to cathode.
More than enough to ruin an esp.
On thyristors that have had over current we usually find the gate drive circuit damaged as well due to this.
I am so sad about the damage to the power supply, hope it gets the required medical attention soon.
Kind regards,
Uncle D
Yep, a thyristor (and also a triac) has the gate connected with the rest of the component, so you do get the high voltage there once it starts conducting and before the current through the inductor gets sufficiently high to make the voltage across the thyristor collapse.
I have made that same experience trying to build a triac regulated supply for a soldering iron many years ago. Getting 48V AC on a puny comparator output will also cause some sparks. Optocouplers (or optotriacs) are you friends here. Or using an IGBT which has the gate actually insulated.
The power supply is repaired now (two dead transistors)
@@AndreasSpiess That's a huge relief, injured lab equipment is not good.
I work with power electronics for a living, it builds character.
But it's like your love for rf which I admire, and appreciate you sharing.
Really impressive lesson and story of your adventure! I learned a lot!
Glad you enjoyed it!
Very interesting and entertaining video Andreas, and I’m totally with you on avoiding high voltage circuits. Back 30 years ago i was hired as a technician to work on our flight warning computers which were all low voltage devices. One day in the lab I witnessed one of our other technicians working on a xenon strobe power supply for an aircraft anti collision light. Im telling you that every time the xenon flash tube fired, it caused the lead wires to physically jump. I knew the xenon strobe power supplies were very high voltage, but to have that much short busts of energy was enough for me to declare I have no interest in that product line.
So we are two that vote for low voltage devices ;-)
Thanks for The proyect of the Gauss gun, is very intructive and also it can become to a prototype of a small of a LHC (Large Hadron Collider) working with a small iron balls.
Yes of course. It's really cool. See also: Ultra power full COILGUN!
th-cam.com/video/s6cFMM6MTpI/w-d-xo.htmlsi=d9uViwHaR6vgnW1g
th-cam.com/video/xY17v43TorU/w-d-xo.htmlsi=ms8LLehidgsVw2Ep
th-cam.com/video/zoA_iUGHyPg/w-d-xo.htmlsi=IuZUGnQfxk9x0d74
The evolution of the bazooka in the third millennium SILENT BAZOOKA (COILGUN - BAZOOKA).
th-cam.com/video/0yvVi1eukeI/w-d-xo.html
@@howardstark6707👍👍👍Awesome!
@@survivalinthezombieapocaly2142 thanks for attention and rating
Been there done that - nothing as exotic as a coil gun how ever, but simply controlling various 220vAC inductive equipment like motors and valves with 5/3.3vDC. Mechanical relays and batteries are your friends in the control circuit where an inductive load can supply you with huge inductive field collapse spikes, even if you use snubbers, MOVs and all sorts of protection. Nothing gets past the mechanical relay separation back into the control circuits. Thanks for your entertaining and informative videos!
Thanks for sharing your thoughts!
Klasse Video, Andreas! Dein sonniger Humor hat mich mehr als einmal zum schmunzeln gebracht. Vermutlich auch wegen des Wiedererkennungseffekts…
Ich dachte, dieses Video sei gut gelungen. Deshalb habe ich es für die Wiederholung ausgesucht.
Seeing this reminds me of my first ever made and sold engine idle controller.
I read some signals on the car, took the idle valve home, made a board with a voltage controller, arduino mini and transistor. So i got to testing in the lab and the only thing i forgot was the flyback diode. Now everything was great.
I put it in the car, tested again, everything worked and then asked a guy to turn on the engine for me.
That was when everything died. including my laptop. So i had to get a new laptop and start again. all fresh parts and WITH every conceivable protection on everywhere. At least have damage control :)
Maybe, maybe. Very probably. Look here: Ultra power full COILGUN!
th-cam.com/video/s6cFMM6MTpI/w-d-xo.htmlsi=d9uViwHaR6vgnW1g
th-cam.com/video/xY17v43TorU/w-d-xo.htmlsi=ms8LLehidgsVw2Ep
th-cam.com/video/zoA_iUGHyPg/w-d-xo.htmlsi=IuZUGnQfxk9x0d74
The evolution of the bazooka in the third millennium SILENT BAZOOKA (COILGUN - BAZOOKA).
th-cam.com/video/0yvVi1eukeI/w-d-xo.html
@@howardstark6707👍👍Amazing!
@@survivalinthezombieapocaly2142 🤝
We all learn with our mistakes. The bigger the pain, the faster the learning ;-)
Also, big SCR's are gated through a 1L1 pulse transformer. That isolates the gate from the logic-level stuff.
I agree that a transformer would be a good solution.
Andreas, it is a good practice to explicitly provide a path for the current to continue to circulate via the coil so that it does not cause overvoltages. Usually it is done using a diode parallel to the coil with a direction opposite of the initial current direction. This removes the possibilities of overvoltage, however it makes the switching off of the current a bit clumsy as the magnetic field drops slower and can draw back the projectile. You can use more advanced calculations to use a resistor connected in series or parallel and also choose a thyristor for the proper calculated voltage to balance the maximum voltage and the time of dropping the current. Maybe you can also use some kind or an air gap or semiconductor overvoltage protection instead of the diode, but I cannot confirm this works fine.
Thank you for your tips!
Andreas, you might want to consider using the working inners of an Airsoft gun shooting plastic BB''s. It uses a pneumatic piston pulled back by an electric motor and has the ability for repeating shots. the velocity of the plastic BB is determined by the spring that drives the piston and is reasonably safe. The individual parts can be bought to allow for tuning the configuration to your needs
This would for sure be a less dangerous method!
I purchased a kit some 30yrs ago from a company called Information Unlimited. It used a 100w incandescent bulb as a charge regulator, bridge rectifier, and a pair of D cell sized caps in parallel. It was mains powered with a knife switch on the output. I used a standard wall switch on the output as it was safer than the blade switch. The coil came already wound. It also used a steel rod as a stator instead of the projectile. The projectiles were copper or AL tube pieces that just slid over the rod. When fired, I got about 30ft distance from the ring. The rod had to be braced though as it would try to center itself on the coil, obviously.
Sorry about your misfortune with the equipment. At least you weren't hurt (other than your nerves maybe).
Today, it probably would be difficult to sell such "dangerous products. So we have to build it ;-) The power supply is repaired (2 dead transistors). Video #228
If you are like me, i feel your pain for your losses...on the plus side there almost always a lesson to be learnt. As a side note, beware that 1/4w resistor have a maximum voltage about 200V or so, better to place 2 or 3 in series in the "high side" for that voltage range.
I agree. Usually I use a few resistors in series in such situations.
I appreciate that you allow us to learn from our mistakes. I would recommend you to look into opto triacs, they are available with dip sockets. With an opto triac in one direction and a optocoupler into the other you would have more safety.
You have kiloed a psu, but what would have happened if this was a lithium battery? Could the bms have rescued it?
Maybe also add a e10 lightbulb in series ti the capacitor to reduce the charge current
And you could probably improve the safety with a second triac (or mechanical switch) to slowly discharge it through a resistor when needed.
I agree with all your recommendations.
Hello from France !! excellent video !!
Thank you (just returned from a bicycle trip to Avignon ;-)
@@AndreasSpiess Good choice !! Very beautiful region ;-)
To make it more interesting, try stacking 8 coils in series along the barrel. sensing the "incoming" bullet to trigger each stage in sequence at ever higher currents. Can we achieve escape velocity? Oh! This going to be FUN!
Indeed, this should be possible. But it is much harder (and probably more dangerous). So it is nothing for a noob like me ;-)
multi Coil 1:1 pulse transformers(used in old DC output SCR motor controls) or Opto Isolators ( LED input to Transistor output) directly from the Line Powersupply feeding the SCR gate along with a limiting shunt, Also a R/C accross the SCR output will help surpress extra crap as it goes along
Thank you for the info. This would have been a much better idea!
Wie immer sehr unterhaltsam, lehrreich und inspirierend!
Super Video :)
Schon mal darüber nachgedacht ein Lasermodul aus einem Lasergravierer auf das ferngesteuerte Fahrzeug zu bauen?
Habe mir gerade eines zum Basteln besorgt und finde es sehr erstaunlich, dass kleine günstige Diodenlaser in den letzten Jahren so stark geworden sind.
Vielen dank.
Pass auf dass dich niemand mit diesem Laser erwischt. Die sind in vielen Ländern verboten, weil gefährlich für die Augen.
Blowing things up is sad but makes for great stories. I blew up a board on an oscilloscope. It was quite a show. I had fire, smoke, sparks, light and noise. Kind of a long story but the short version was I slipped with a meter probe from a 5 volt copper run on the circuit board to a 500 volt copper run. Many small components disappeared. But I'll never play with a rail gun. Small fast free flying metal parts frighten me.
I also do not like high voltages above 24V. But I had to try this one ;-)
I was photographing some members of the Arsenal soccer team once. I was using a grnerator to power my flash units. It began to rain a little and a Zener Diode in one of my Swiss Elinchrom flash units. The sound was like a rifle being fired. When I turned back to explain it to the players they were all hiding in the bushes.
I can imagine that this was scary for them!
Nice recap!
Glad you enjoyed it!
As others have suggested, a pulse transformer is probably a better option for the gate trigger and I'm not sure about floating gates (though many devices seem to use them). Suggest also a snubber to protect the ESP (spikes back through the transformer when the thyristor switches off). My knowledge is not sufficient to determine what happens to the output voltage on the boost converter when the thyristor switches off and the coil collapses, there may be a very large spike.
I also do not know what happens. But maybe the current is already low because the capacitor is discharged when the thyristor opens.
Confessions of an engineer...very entertaining. Hope you fixed you supply easiliy
Two dead transistors...
Add current limiting to the gate of the thyristor, using some 47kohms or so. As soon as the thyristor triggers, the gate gets connected to the anode. That is what kills everything
It seems so that this is a dangerous pin ;-)
@@AndreasSpiess indeed it is. My first thyristor circuit ended up in a ball of flames: a Zener, a resistor and a BC548 fried instantly after 150V got connected...
You need an RC snubber circuit across the SCR. SCR is a simple device but without protection, and big inductive load you will get a big voltage spike as large as L*di/dt. A simple RC snubber should do it. The villain is not the SCR, it's the large inductance. What is the inductance of the coil? Also, maybe a Diode backward across the coil will help.
Absolutely correct! Inductance will vary with the position of the projectile.
Keep in mind that the switch is only opened when the cap is discharged.
did you consider a flyback diode across the coil to clamp the reverse volt spike that can go into the 1000V+ range?
Now I would add one ;-)
Dear Andreas, no need for microcontroller, just charge a 0.01uF capacitor with like 100k ohm and discharge it with a short to ground resistor 1kohm +- that is connected parallel to gate.. And the capacitor will trigger the gate and discharged by the low resistor and gate, maybe a 1.5v Zener diode can replace the battery
Good idea!
I think that the best way to drive thyristor in that kind of circuits is a transformer. But i know a defibrillator that uses a H-bridge made of opto-thyristors with some additional circuit to close them in right time to provide patient impulse of right waveform. And that circuit works ok, providing short biphasic impulse of ~ 2kV and 40A. Maybe you will find it useful next time.
Thank you for the info!
Later this year:
Wife: "Andreas, I can't find our wonderful Christmas tree balls. Have you seen them?" 🎄
Andreas: "Uhm... Nope!" 😇
:-))
I use a TS117 for the cpu to trigger the SCR and the other half gives me feedback for error conditions. Also a big diode across the coil.
These solid state relays are quite handy, I agree.
Maybe a high voltage flyback diode on that big coil might help tame the circuit a bit? Always optical isolator or a nice little reed relay with flyback diode power by a 2n2222 transistor?
I always use an optoisolator now whenever there is a large inductive load being switched even at low voltage. Flyback diode is sometimes sufficient protection for small inductors like on hobby DC motors
@@bornach Optoisolator may be overkill. My rule of thumb is that if switching current from gpio trough 330Ω resistor isn't enough, use additional transistor or more involved circuit. Also don't forget a snubber.
@@pasikavecpruhovany7777 An abundance of caution is warranted when messing with a 400V DC boost converter that additionally provides a negative rail. Who knows whether it would have been safe to create a ground loop with the ESP8266 development board that was still plugged in via USB into a PC that was powered by mains electricity
I have that exact boost converter and it outputs more than double the stated voltage
So you had more luck than me ;-)
@@AndreasSpiess I built something similar a few years ago with the same boost converter. I used a beefier SCR (skkh92/12e) and I guess I did get lucky with the boost converter. I have killed a power supply in a very similar way that you did, but in my case it was when I was building my first Tesla coil :(
Maybe I missed something, but was there diode parallel to the coil? If not, then pretty much everything can go wrong... also spikes from the thyristor gate should be protected with zener or similar.
I agree!
Optocouplers will be a big help. Also, you can find some with photo-darlington outputs that may help
I agree, that would have helped.
DC supply should shut off when sufficient voltage is in the capacitor. Double diodes on the supply side to the capacitor to be sure.
Turn DC supply back on when capacitor has drained. Higher velocity and efficiency may be achieved by using two coils in series with the second triggered slightly later. The impedance of the coils will change as the slug moves through which may be used as a "passive" circuit effect for triggering. i.e. the coil goes from iron core to air core.
Other designs use several coils in series with photodiodes for triggering. But this is nothing for me ;-)
I love it. I missed it first time around and this has to be one of your best. What did you tell the missus after the explosion? I was just maintaining my gun!
I also thought that this video deserves a re-appearence ;-)
Hi Andreas. I was just wondering if it was the back EMF from the coil that killed the ESP2866? Would a flyback diode have helped?
There are many proposals in the comments on how to avoid the damage.
@@AndreasSpiess It was less a suggestion, as I don't have anywhere near your knowledge and experience, and more of a question.
@@gerryjamesedwards1227 I know. And my answer was not polite 😞Sorry about that.
@@AndreasSpiess no, no problem at all with your reply, I'm sure you have lots of comments to get through.
I've worked with HV for a personal project and... well, I called my parents when I was done with it. Now, when I want to make a coilgun, I just stick with high-amp designs instead of high voltage designs! Thankfully, lion batteries and supercaps make this possible!
If you want to try the same, a 6s (~40V) lithium battery can still supply hundreds of amps on a compact coil, so you can have a fun plinker without the danger factor!
Indeed, high amperes got much easier these days. But they still need a lot of copper ;-)
We used a darlington transistor that dumps an isolated cap both sides to the scr or thyristor
Good idea!
Did you have a diode across the coil to shunt the back emf?
No. But a thyristor only opens when there is no current anymore..
Could the capacitor be swapped with a couple 6S lipo batteries to reduce the voltage?
Maybe. Then, you would need very thick wires.
After thinking about this a little more. It is clear of the problem. You are charging the inductor and getting the magnetic field high enough to push out the nail. The controller then interrupts the current. As the magnetic field collapses, the voltage will go way up (Lentz' law). The RC snubber will be a good idea but it better is large MOV (Metal Oxide Varistor )across the SCR. The watch the joule rating of the MOV.
Are you sure that the voltage goes up in this design? The thyrisor only opens when the current is very low. But for sure it would be worth adding such a diode. Just in case...
Oh wow, imagine throwing a hissy fit because a youtuber built an electric gun for a little tank :D
I built hairspray powered potato guns when I was a kid, it was super fun!
Cheers!
Hairspray indeed can be quite useful ;-)
Check voltage limits on the 1/4w resistors, I think it’s 250v
You can put 2x400k instead of 1x800k
I agree. I usually combine a few resistors, too.
As the trigger is so fast that it generates high voltage in this circuit by the principle of counter electromotive force, by Lenz's law. To avoid this, it is recommended to use a diode in reverse polarity, parallel to the capacitor.
Yup. I pointed this out back in 2018 via Twitter when the original video came out. Beware of adapting random projects found on Instructables or elsewhere on the Internet that were not originally intended to be hooked up directly to microcontrollers. I've destroyed lots of cheap low voltage electronics simply by connecting them to inductive loads. The 400V wasn't even necessary.
@@bornach Indeed. The same care is needed when using relay because it is a inductive load as well.
@@gplgomesThe cheap Chinese relay module that Andreas showed in the video I think already contains an optoisolator, transistor and diode.
Good video! Awesome to push through even if it wasn't going 100% as planned. Yeah, high voltage and especially high currents to (even remotely) interface with 3V/5V logic I tend to carpet bomb with TVS, zener diodes and series resistors. Built an array of heavy duty solenoids to switch 160A circuits to different places (to massive transformers)... the idea was that it should only switch when current was off... but its a machine, so one can never be 100% certain, and I like to sleep during nights and not rush in to keep production running 24/7. So, a bit of belt and suspenders to keep my pants up! ...but ofcoz there was some minor component casualties during development, as it should, if you want to find out the limits/worst case. I always kept a healthy dose of fear, heightened awareness of where; the metal tools, fingers and elbows are when fiddling about near that circuit/system... and keep it behind locked doors and warning signs. Fully Charged Coke can sized caps does that to me.
If you are lucky... the wife will already own one !!
@@johncoops6897 . . 🤔 . I need help to understand... or maybe answer stuck to wrong post?
@@Paxmax - sorry, my comment ended up on wrong post! I was replying to @AdityaMehendale about finding Epilator devices 😂😂
@@johncoops6897 Haha! 😂 no worries, it seems like randomly youtube does this, happened twice in last 6 months to me too! My comment shows up seemingly at complete unexpected place (I'm not sure if it is(/was) early demensia... or utube glitch.
Can you use an optocoupler to trigger the thymistor to ensure any feedback might not smoke a valuable ESP
I think so. But I did not try.
my arduino survived every trigger event. But I used a mcp1407 gate driver, that was connected to the arduino by a resistor. That might have been enough isolation. Everything worked fine until the IGBT (that I used instead of a thyristor) popped. I guess I was too close to its maximum power limit. After that boom I stopped playing with high voltage.
A boom often helps in decision making ;-)
A 2005-2009 Toyota Prius inverter has a boost/buck converter and high capacity IGBTs built into it with an external harness to control everything and can reach 600v all for around $60 USD. Just incase you are looking for a high quality power supply for high voltage and current projects.
Good idea. If it is Toyota, it must be of quality
@@AndreasSpiess this guy @evbmw has a lot of information on his channel about using those inverters. In one video he shows that he blew a capacitor bank on a gen3 Prius inverter and it still worked.
It's a miracle you didn't also kill that absolutely beautiful MSOX3054T...
No miracle. I pay extreme attention to this one. Plus it is not as easy to kill, I assume ;-)
that gunshot sound scared the shit out of me
That was the goal ;-)
EMF concern: I was especially worried that there was no isolation on the capacitor charge-sensing voltage divider. You claimed that it would express the maximum voltage as less than a volt to the MCU. But, back-EMF from a coil like that could be in the thousands of volts! Even after the 400:1 voltage divider does its work, the resulting voltage to the MCU could still damage it.
Maybe the thyristor is handling the reverse voltage spike (back-EMF). But, I doubt it is rated for that kind of voltage. I'd definitely also use a flyback diode on the high side of the coil.
Are you sure this coil creates any back EMF? The thyrisor only opens when the current is nearly zero. Before, the coil is firmly connected to the capacitor
It's coil so runnning 200A thru will do nice back and forth with the voltage putting directly into esp32 also some protection for the thyristor should be added and the converter but I'm not woried that much for that
I agree.
Zener and flyback diodes may have helped as well.
I agree!
I love burned cap smell at the morning 🥰
:-))
I wonder if this gun could be made large enough to shoot a small arrow tied to a fishing line some 15-20 meters high. It would be quite handy to hang antennas on high trees.
There are probably easier ways to do that. Most people use pressed air as energy source. Less dangerous...
I would very much like to know if you are able to fix your lab power supply. If so (or even if not} please make a video of your journey.
I already made a video about it.
I would assume that even your voltage divider is at risk, since the the coil might push back some high inductive voltage when it recovers, that could exceed the 400V you assumed for the divider network. Not sure sure i a shotkey diode might block that.
I vote for complete insulation in this case. As you describe, there are many effects, and the modern MCUs are quite vulnerable.
@@AndreasSpiess I designed a few high voltage, high current power supplies in the past. Namely for Xenon short arc lamps, laser tubes etc.. 50-100A current @ 20-50V DC, with striking voltages in the 10s of kilovolts... So I feel the pain :)
Show us your gun. What model is it and do you have any upgrades on it?
I gave mine back when I had the age. No need around the house for it ;-)
...so sorry to see the casualties :-( , well, at least for us was fun to watch and entertaining ;-)
The power supply is also repaired now. Only two transistors...
I've gone trough similar dramas and frustrations and know how you felt after the power supply worked again after replacing the second power transistor ... 🙂
Magic smoke is a thing here. Lucky you didn't wear the cap, Andreas. Now, back to think of 600KV, learning Tesla stuff.
Too much voltage for me. I hardly can handle 400V ;-)
@@AndreasSpiess lol live a bit, or is that die a lot. 😆
Hallo Andreas, wegen der rechten Seite deines Netzteils: ich vermute daß Du daran einen Kurzschluß von außen an den Terminals mißt. Deshalb brennt auch bei der kleinsten Spannung die OC LED. Diese Netzteile haben oft eine (dickere) Diode als Verpolschutz am Ausgang. Wenn du Glück hast reicht es diese erstmal zu entfernen bzw. weiter zu ersetzen. Grüße.
Unterdessen ist es repariert. Zwei Transistoren mussten ersetzt werden... Waren aber nicht teuer.
Cool!@@AndreasSpiess
Interesting parts are score-able from "photoepilator" IPL devices. In such a device, too, a large and low-ESR capacitor is used to dump energy into a xenon flash-lamp (400V / 50A / 5ms) using an IGBT (optically isolated gate). A battery-operated model also has a DC-DC stage to charge the cap to ~400V. The coil is not included :) I can imagine that devices where the xenon-tube is kapot can be obtained for low monies; as it is a "consumer-grade" device, these should be not too hard to come by, albeit with a low W.A.F.
If you are lucky... the wife will already own one !!
@@johncoops6897 ergo the "low WAF" :)
Interesting idea!
@@AndreasSpiess One of your subscribers has a nice demo along these lines: th-cam.com/video/OiP6YZWVBug/w-d-xo.html - they use a spark-gap switch instead of an IGBT.
@@AdityaMehendale Interesting concept. I did not know that "air" conducts that good...
The negative rail of an isolated 400v boost supply might be hundreds of volts from the ground on the input supply.
I agree.
are there no opto-couplers in your assortment stash ? 😅🙈
There are (and now I would use one of them)
We had a buy who brought in his half meter tall Van De Graff generator into the lab. It killed two scopes and a power supply that were not connected to anything except power before we could get it shut down. We saw sparks jumping between the test benches, could have been worse.
Hopefully, the boss never heard what happened ;-)
Did you check the voltage when you switch the circuit off, pretty sure the coil could generate several hundred volts
The capacitor has to be discharged before the thyristor opens. But I never checked.
HV single stage coilgun may look fun but it's highly inefficient (and obviously dangerous to play with). Optimized LV multi stage design can achieve better performance while being relatively safe.
I agree.
So, we have to isolate EVERYTHING with a high voltage/high currents combination, even from EMPs. Noted. Thank you! Your power supply won't be forgotten.
The power supply is already repaired ;-)
A very interesting project. I enjoyed watching it. I'm wondering if you ever came across the Electronoobs version of this project during your TH-cam viewing? It might give you inspiration. Andrei's video is called "I've Made a Powerful COILGUN | Separate Stages PCB"
Thanks for sharing.
Yes, I saw it. Greatscotts and my videos aired first in 2018. So maybe he took them as an inspiration
@@AndreasSpiess Ah. I didn't realize that. Thank you
Sorry about the power supply. I hope you can get a new one soon.
Thank you for your support! I was even able to fix the power supply myself. Two transistors were destroyed.
I would add a switch and resistor load to discharge the cap if the bullet doesn't fire as a safety measure.
Good idea!
Hi Andreas what is/was your profession?
I am a trained electronics engineer with a PhD in Business administration. However, I did not work as an EE for a long time.
Thank you for another great video! Just don't shoot yourself while testing your weapon!
I would not consider it as a weapon. It was more an experiment. But still dangerous, I agree.
You can learn something new everyday - more reason to keep going
I agree. Even with 66 ;-)
To isolate the MCU from any spikes, could you have used a logic shifer in place of a relay? If you connected the low side to the MCU and the high side to rhe thyristor, you could have achieved a switching voltage of 5V. Although I may be missing something here.
I do not know if it would work. Somebody would have to try it.
Future video - board level repair of damaged bench power supply? Or collaborate with channel Mr Carlson's Lab?
See video #228 How does a Linear Power Supply work (incl repair)
Thanks. I will post a link to this video.
A repair video of the power supply?
Already done ;-)
Hmm for a long time I have wanted to build a coil gun, but my concern has been accidental discharge in a random (my) direction. Maybe I should stay with petrol bombs or gas bombs as they are very predictable due to their simplicity of just a switch, two leads and a container with a bit of fuel :)
You decide ;-)
I over voltaged a cap and it exploded. The case hit me in the leg leaving a large welt. I survived and went on to become an electronics design engineer.
Good decision!
400V is still low voltage, sure its higher then the very low voltage stuff used in microelectronics, but its still low. Its so low you don't even have to worry about the electrons leaking out the conductors.
Still a bit more challenging to work with then 5V, but overall still relatively easy. things get increasingly difficult at around 5KV, then increase in difficulty to medium at around 50KV and go to hard at around 1MV
For me, everything above 24V is high voltage ;-) And I am happy that others master these voltages.
@@AndreasSpiess At least with such low voltages, you don't risk death or serious bodily harm if you happen to brush past the wrong thing at the wrong time. Its all a matter of perspective
Oh, and above about 5KV the circuit can be closed if your still a few mm away from the conductors. Things get even more fun the higher up you go. Such as at 1MV, where you can get a shock / become part of the circuit, if you happen to stray to within 1 meter of any part of the system at that voltage. Even more fun can be had if medium and or high voltage and high current are mixed. Though the fun starts at around 200V with high current. Basically, if things fail, they will usually do so in a spectacular manner.
Basically put, medium and high voltage stuff requires some amount of planning to prevent accidents, sub 24V usually not so much. though i have had very large capacitors explode on me at those voltages.
Nice playgrund. 😊
Indeed. And I learned something.
Well... I have to say, a good idea for the day, carry on for the next day, rail gun please!
After this experience, I decided that I am not the right person for such projects :-(
I want a sensor which can find the coordinates of a moving ball in 0.5/1 seconds from A to B ,please suggest me a sensor
I do not know such a sensor :-(
@@AndreasSpiess i want to track the projectile motion of a slow moving ball ,can VL53L0X TOF Based LIDAR Laser Distance Sensor be helpful for tracking the co ordinates of a slow moving ball within its field of view?
@@59vijaiyaaravindthsr39 You have to compare the datasheet with your needs.
thanks @@AndreasSpiess