Ring launcher optimum oscillator frequency
MRMILSTAR, Fri Feb 15 2019, 04:11PMI am going to build a ring launcher. I want to re-use the pulse capacitor on my quarter shrinker and other ancillary circuitry to avoid replicating equipment. The capacitor is huge and weighs about 180 pounds. It is an Aerovox pulse capacitor measuring 100 uF at a maximum of 22 KV. Fully charged, this monster can output 24 KJ. Obviously for my ring launcher I am not going to come any where close to fully charging this capacitor to avoid total destruction of the ring launcher. Maybe a few KV.
Given that I would like to re-use this capacitor and my other ancillary quarter shrinker circuitry, what would be the "best" oscillation frequency to use when triggered? This frequency will obviously determine the number of turns required for the launching inductor. Is there an optimum oscillation frequency? The primary projectile I will be launching will probably be old hard drive platters.
Re: Ring launcher optimum oscillator frequency
klugesmith, Fri Feb 15 2019, 11:25PM
From the design frequency, you want to figure the inductance and thus turns count, right?
Why not start by making 2 coils with substantially different turns count, and compare the launching performance? That will guide you toward an optimal design.
I would explore the turns-count sensitivity, and optimum value, at a low stored-energy setting. Tens or hundreds of volts. Measure ultimate height of platter in inches, instead of measuring size of crater in your ceiling.
Then crank up the energy, using your assortment of coils, and see how the optimum frequency shifts.
The system is basically linear, at a fixed frequency and damping ratio, with output exactly proportional to input. (Frequency and damping ratio with and without platter will be different). It begins to go nonlinear when platter moves substantially, or conductors become very hot, during the main part of the current pulse. I bet the geometry change will kick in long before the temperature coefficient effect, unless you have the platter physically driving a brick or something.
Did you ever tell us about your quarter shrinker, beyond the planning stage?
klugesmith, Fri Feb 15 2019, 11:25PM
From the design frequency, you want to figure the inductance and thus turns count, right?
Why not start by making 2 coils with substantially different turns count, and compare the launching performance? That will guide you toward an optimal design.
I would explore the turns-count sensitivity, and optimum value, at a low stored-energy setting. Tens or hundreds of volts. Measure ultimate height of platter in inches, instead of measuring size of crater in your ceiling.
Then crank up the energy, using your assortment of coils, and see how the optimum frequency shifts.
The system is basically linear, at a fixed frequency and damping ratio, with output exactly proportional to input. (Frequency and damping ratio with and without platter will be different). It begins to go nonlinear when platter moves substantially, or conductors become very hot, during the main part of the current pulse. I bet the geometry change will kick in long before the temperature coefficient effect, unless you have the platter physically driving a brick or something.
Did you ever tell us about your quarter shrinker, beyond the planning stage?
Re: Ring launcher optimum oscillator frequency
MRMILSTAR, Sat Feb 16 2019, 04:20AM
I am in the process of building my quarter shrinker now. It is my winter project. I have most of the parts. I am currently working on the high energy switch which is the most difficult item to build to handle this amount of energy safely and reliably. This will be the most dangerous device that I have built with the capability of being charged to 24 KJ at its maximum charge voltage of 22 KV. However I never expect to use that amount of energy. It would obliterate the coin.
I am asking about the ring launcher now so that I can easily incorporate it into the quarter shrinker architecture in the future. I may have to use a direct-contact type of switch for the lower-energy ring launcher because the minimum separation between electrodes for the quarter shrinker switch will be about 1 mm to prevent the electrodes from welding together. This is acceptable for the quarter shrinker because it will be operating at greater than 6 KV. I cannot get reliable firing at only a few kilovolts for the ring launcher with an air gap switch.
3 KV would correspond to 450 joules with my capacitor. If the ring launcher coil can take this without breaking up, using 3 KV/mm as the dielectric strength of air for flat plates, I may be able to use the same air gap switch for the quarter shrinker and ring launcher. I have seen ring launchers with 1500 joules and the coil stayed intact, but these all seem to have been built with electrolytic capacitors which don't have a high discharge rate. Since I am using an Aerovox energy discharge capacitor, which has an extremely fast discharge time, I don't think I can make reliable performance comparisons between a launcher using electrolytic capacitors and one built with an energy discharge capacitor.
By the way, this ring launcher will be operated outdoors as will the quarter shrinker.
MRMILSTAR, Sat Feb 16 2019, 04:20AM
I am in the process of building my quarter shrinker now. It is my winter project. I have most of the parts. I am currently working on the high energy switch which is the most difficult item to build to handle this amount of energy safely and reliably. This will be the most dangerous device that I have built with the capability of being charged to 24 KJ at its maximum charge voltage of 22 KV. However I never expect to use that amount of energy. It would obliterate the coin.
I am asking about the ring launcher now so that I can easily incorporate it into the quarter shrinker architecture in the future. I may have to use a direct-contact type of switch for the lower-energy ring launcher because the minimum separation between electrodes for the quarter shrinker switch will be about 1 mm to prevent the electrodes from welding together. This is acceptable for the quarter shrinker because it will be operating at greater than 6 KV. I cannot get reliable firing at only a few kilovolts for the ring launcher with an air gap switch.
3 KV would correspond to 450 joules with my capacitor. If the ring launcher coil can take this without breaking up, using 3 KV/mm as the dielectric strength of air for flat plates, I may be able to use the same air gap switch for the quarter shrinker and ring launcher. I have seen ring launchers with 1500 joules and the coil stayed intact, but these all seem to have been built with electrolytic capacitors which don't have a high discharge rate. Since I am using an Aerovox energy discharge capacitor, which has an extremely fast discharge time, I don't think I can make reliable performance comparisons between a launcher using electrolytic capacitors and one built with an energy discharge capacitor.
By the way, this ring launcher will be operated outdoors as will the quarter shrinker.
Re: Ring launcher optimum oscillator frequency
Sulaiman, Sat Feb 16 2019, 10:52AM
A thin flat disk sounds very un-aerodynamic,
short lengths of copper pipe/tube may be more suitable for launching ?
Sulaiman, Sat Feb 16 2019, 10:52AM
A thin flat disk sounds very un-aerodynamic,
short lengths of copper pipe/tube may be more suitable for launching ?
Re: Ring launcher optimum oscillator frequency
MRMILSTAR, Sat Feb 16 2019, 03:57PM
True enough that the flat disk has terrible aerodynamics. For high-power launchers, this may be an advantage. I have seen videos of high-power launchers shooting these disks upwards of 50 feet even with the terrible aerodynamics. Since they are flat, they tumble when coming down which slows their speed. I really don't want anything dangerous coming down on my or anyone else's head. The disk drive platters are made of aluminum and are readily available and I have a big stack of them. Being 5 inches in diameter, they are also pretty visible in the air especially if I paint them fluorescent orange or green. I can always try a different projectile later if I can figure out a way to make them somewhat safe when falling.
MRMILSTAR, Sat Feb 16 2019, 03:57PM
True enough that the flat disk has terrible aerodynamics. For high-power launchers, this may be an advantage. I have seen videos of high-power launchers shooting these disks upwards of 50 feet even with the terrible aerodynamics. Since they are flat, they tumble when coming down which slows their speed. I really don't want anything dangerous coming down on my or anyone else's head. The disk drive platters are made of aluminum and are readily available and I have a big stack of them. Being 5 inches in diameter, they are also pretty visible in the air especially if I paint them fluorescent orange or green. I can always try a different projectile later if I can figure out a way to make them somewhat safe when falling.
Re: Ring launcher optimum oscillator frequency
Sulaiman, Sat Feb 16 2019, 07:55PM
I mentioned the aerodyamics because the projectile size and geometry affects launcher design,
but you are right, I had not considered the projectile return, (and visibility),
hdd platters are a much better choice than I realised..
So, I guess that my idea of using razor blades as fins is also not very useful ;(
Sulaiman, Sat Feb 16 2019, 07:55PM
I mentioned the aerodyamics because the projectile size and geometry affects launcher design,
but you are right, I had not considered the projectile return, (and visibility),
hdd platters are a much better choice than I realised..
So, I guess that my idea of using razor blades as fins is also not very useful ;(
Re: Ring launcher optimum oscillator frequency
klugesmith, Sun Feb 17 2019, 04:21AM
No need to make a direct-contact switch.
The firing switch for my can crusher has shiny spherical electrode faces (approx 1 cm radius of curvature). Minimum separation is set by a limit screw, so they could be allowed to touch. But a finite minimum air gap works fine at 1000 volts, which is 26 joules on my capacitor and would be 50 joules on yours, and can visibly indent a can (barely). When the open-circuit voltage is higher, the switch fires earlier (no need to adjust the minimum gap). My moving contact is attached to the short arm of a lever. The long arm is moved by pulling a lanyard made of non-conductive string.
I hope you are not planning to waste effort on some kind of electrically triggered spark gap, even for the quarter shrinker. More complication = less safety and reliability. Bert Hickman uses a mechanically operated spark gap. I think the Hackerbot guys used a string to remove a block that held a slightly glorified clothespin open. An unenclosed spark-gap switch can make a firecracker-like bang when it goes off.
Back to frequency -- why don't you start by figuring a lower bound, by yourself? What's the time scale for platter departing from coil, in the 1500 joule launcher you mentioned? How does that compare to the first cycle of damped oscillation, for some hypothetical coils with various inductances and realistic values for resistance? You could use Barry's Coilgun Calculator. To keep it simple, omit the inductively coupled platter from the effective L and R model.
klugesmith, Sun Feb 17 2019, 04:21AM
No need to make a direct-contact switch.
The firing switch for my can crusher has shiny spherical electrode faces (approx 1 cm radius of curvature). Minimum separation is set by a limit screw, so they could be allowed to touch. But a finite minimum air gap works fine at 1000 volts, which is 26 joules on my capacitor and would be 50 joules on yours, and can visibly indent a can (barely). When the open-circuit voltage is higher, the switch fires earlier (no need to adjust the minimum gap). My moving contact is attached to the short arm of a lever. The long arm is moved by pulling a lanyard made of non-conductive string.
I hope you are not planning to waste effort on some kind of electrically triggered spark gap, even for the quarter shrinker. More complication = less safety and reliability. Bert Hickman uses a mechanically operated spark gap. I think the Hackerbot guys used a string to remove a block that held a slightly glorified clothespin open. An unenclosed spark-gap switch can make a firecracker-like bang when it goes off.
Back to frequency -- why don't you start by figuring a lower bound, by yourself? What's the time scale for platter departing from coil, in the 1500 joule launcher you mentioned? How does that compare to the first cycle of damped oscillation, for some hypothetical coils with various inductances and realistic values for resistance? You could use Barry's Coilgun Calculator. To keep it simple, omit the inductively coupled platter from the effective L and R model.
Re: Ring launcher optimum oscillator frequency
MRMILSTAR, Sun Feb 17 2019, 04:39AM
I am sticking with "simple". I am basing my spark gap switch on Bert Hickman's design. I have been in communication with him. With careful construction, my objective is to allow the two electrodes to get as close as 1 mm while maintaining good parallelism of the electrode faces. This will allow me to trigger at fairly low voltages and maintain even wear across the electrode faces. I am also using simple fool-proof and safe string lanyards to operate the various switches.
I am going to test my flat-plate spark switch to see how low a voltage I can reliably trigger. Maybe I won't need a separate switch for the low voltage ring launcher. If that doesn't work out, I may have to experiment with your ball bearing spark gap switch for low voltage operation.
I did some computations today to figure out how thick my conductors need to be for the quarter shrinker. Using my 100 uF capacitor and assuming a 10-turn, 1 inch diameter work coil, the resonant frequency came out to be about 8500 Hz. The skin depth for copper at that frequency came out to be about 0.7 mm. This tells me that my conductors have to be at least 1.4 mm in thickness, assuming flat-bar conductors.
MRMILSTAR, Sun Feb 17 2019, 04:39AM
I am sticking with "simple". I am basing my spark gap switch on Bert Hickman's design. I have been in communication with him. With careful construction, my objective is to allow the two electrodes to get as close as 1 mm while maintaining good parallelism of the electrode faces. This will allow me to trigger at fairly low voltages and maintain even wear across the electrode faces. I am also using simple fool-proof and safe string lanyards to operate the various switches.
I am going to test my flat-plate spark switch to see how low a voltage I can reliably trigger. Maybe I won't need a separate switch for the low voltage ring launcher. If that doesn't work out, I may have to experiment with your ball bearing spark gap switch for low voltage operation.
I did some computations today to figure out how thick my conductors need to be for the quarter shrinker. Using my 100 uF capacitor and assuming a 10-turn, 1 inch diameter work coil, the resonant frequency came out to be about 8500 Hz. The skin depth for copper at that frequency came out to be about 0.7 mm. This tells me that my conductors have to be at least 1.4 mm in thickness, assuming flat-bar conductors.
Re: Ring launcher optimum oscillator frequency
Sulaiman, Sun Feb 17 2019, 11:20AM
two tiny details;
if skin depth os 0.7mm then you need at least 3x 0.7 = 2.1mm thickness for the approximations to be valid.
'string' to me implies multi-strand which can retain (electrically conductive) moisture,
use mono-filament fishing line or similar.
Do you already have earplugs and ear defenders (and goggles/face shield just in case..)
Sulaiman, Sun Feb 17 2019, 11:20AM
two tiny details;
if skin depth os 0.7mm then you need at least 3x 0.7 = 2.1mm thickness for the approximations to be valid.
'string' to me implies multi-strand which can retain (electrically conductive) moisture,
use mono-filament fishing line or similar.
Do you already have earplugs and ear defenders (and goggles/face shield just in case..)
Re: Ring launcher optimum oscillator frequency
MRMILSTAR, Sun Feb 17 2019, 03:45PM
I realize this sounds like a shotgun going off so, yes, ear protection will be mandatory. Good suggestion about the mono-filament line and skin depth.
I am still pondering the blast cage. Initially I was going to use a 12" x 12" x 12" section of of 1/4" thick steel square tubing, however this weighs about 40 pounds and is conductive which complicates bus bar entry and exit points. This might be overkill. I am also considering building a blast cage from 1/4" thick G10 joined at the corners by angle iron. This would be a lot lighter and is non-conductive. It would also be easier to cut. I have seen blast cages made from thinner aluminum for shrinkers with similar power and that seems to hold up. Any thoughts about the blast cage?
MRMILSTAR, Sun Feb 17 2019, 03:45PM
I realize this sounds like a shotgun going off so, yes, ear protection will be mandatory. Good suggestion about the mono-filament line and skin depth.
I am still pondering the blast cage. Initially I was going to use a 12" x 12" x 12" section of of 1/4" thick steel square tubing, however this weighs about 40 pounds and is conductive which complicates bus bar entry and exit points. This might be overkill. I am also considering building a blast cage from 1/4" thick G10 joined at the corners by angle iron. This would be a lot lighter and is non-conductive. It would also be easier to cut. I have seen blast cages made from thinner aluminum for shrinkers with similar power and that seems to hold up. Any thoughts about the blast cage?
Re: Ring launcher optimum oscillator frequency
Uspring, Sun Feb 17 2019, 05:33PM
There is a LTSpice simulator for a ring launcher in this thread. It might help to find an optimum L.
Uspring, Sun Feb 17 2019, 05:33PM
There is a LTSpice simulator for a ring launcher in this thread. It might help to find an optimum L.
Re: Ring launcher optimum oscillator frequency
klugesmith, Sun Feb 17 2019, 07:10PM
Re. blast cage: why not a simple box filled with sand? Quarter-shrinking generates tiny high-velocity fragments, without much "blast" energy, IMHO. You could surround the box with bricks or concrete blocks for initial trials. Then vacuum out the sand to see how far the metal fragments went. If the sand is dry enough to flow, it's dry enough not to interfere with the electricity.
Bottom of "production" box could be funnel-shaped. After a shot, remove bottom cap. Sand and metal bits drain into your sifting screen, thence into open sand-storage pail. Ready to pour into loaded box for next shot.
Whether for shrinking quarters or launching disks, I think skin effect in copper wire is a secondary consideration. For thin wire, you get to use its full conductivity all the way to the middle. Very thick wire needs to be derated some for skin effect, but the factor is small unless wire is unnecessarily thick for other reasons.
1. The damping effect of wire resistance falls off when total circuit R is much lower than Z = sqrt(L/C) of tank circuit. I figure Z is about 0.2 ohms for the 8500 Hz example you gave, and for my can crusher. Quarter shrinking time (ref. Hackerbot highspeed video) is comparable to one cycle of undamped oscillation.
2. The wire needs to be sized to withstand I-squared-T value of discharge pulse, without getting hot enough to damage its insulation. Go work it out. I'm guessing 8 AWG is plenty, even for quarter shrinking, but you can check with Bert or Uspring. Hackerbot narration is very wrong when it says "this brilliant light is our work coil vaporizing". Torn to bits, yes. But the whole initial energy is too small to even melt more than a fraction of 1% of the work coil mass.
Here's how a quick & dirty spreadsheet responded to cutting and pasting:
var unit R_CC1 M_QS1
C uF 52 100
L uH 2 3.5
C F 0.000052 0.0001
L H 0.000002 0.0000035
Z ohm 0.196116135 0.187082869
T s 1.0198E-05 1.87083E-05
F Hz 15606 8507
klugesmith, Sun Feb 17 2019, 07:10PM
Re. blast cage: why not a simple box filled with sand? Quarter-shrinking generates tiny high-velocity fragments, without much "blast" energy, IMHO. You could surround the box with bricks or concrete blocks for initial trials. Then vacuum out the sand to see how far the metal fragments went. If the sand is dry enough to flow, it's dry enough not to interfere with the electricity.
Bottom of "production" box could be funnel-shaped. After a shot, remove bottom cap. Sand and metal bits drain into your sifting screen, thence into open sand-storage pail. Ready to pour into loaded box for next shot.
Whether for shrinking quarters or launching disks, I think skin effect in copper wire is a secondary consideration. For thin wire, you get to use its full conductivity all the way to the middle. Very thick wire needs to be derated some for skin effect, but the factor is small unless wire is unnecessarily thick for other reasons.
1. The damping effect of wire resistance falls off when total circuit R is much lower than Z = sqrt(L/C) of tank circuit. I figure Z is about 0.2 ohms for the 8500 Hz example you gave, and for my can crusher. Quarter shrinking time (ref. Hackerbot highspeed video) is comparable to one cycle of undamped oscillation.
2. The wire needs to be sized to withstand I-squared-T value of discharge pulse, without getting hot enough to damage its insulation. Go work it out. I'm guessing 8 AWG is plenty, even for quarter shrinking, but you can check with Bert or Uspring. Hackerbot narration is very wrong when it says "this brilliant light is our work coil vaporizing". Torn to bits, yes. But the whole initial energy is too small to even melt more than a fraction of 1% of the work coil mass.
Here's how a quick & dirty spreadsheet responded to cutting and pasting:
var unit R_CC1 M_QS1
C uF 52 100
L uH 2 3.5
C F 0.000052 0.0001
L H 0.000002 0.0000035
Z ohm 0.196116135 0.187082869
T s 1.0198E-05 1.87083E-05
F Hz 15606 8507
Re: Ring launcher optimum oscillator frequency
MRMILSTAR, Sun Feb 17 2019, 08:07PM
The term "vaporized" is almost always used incorrectly. The work coil isn't turned to vapor, except for maybe a negligible part, it is disintegrated.
I have a lot of copper bus bar left over from other projects so that is what I plan to use even though it takes work to bend it around. I just have to keep things spaced far enough apart to avoid flash over.
MRMILSTAR, Sun Feb 17 2019, 08:07PM
The term "vaporized" is almost always used incorrectly. The work coil isn't turned to vapor, except for maybe a negligible part, it is disintegrated.
I have a lot of copper bus bar left over from other projects so that is what I plan to use even though it takes work to bend it around. I just have to keep things spaced far enough apart to avoid flash over.
Re: Ring launcher optimum oscillator frequency
klugesmith, Sun Feb 17 2019, 11:37PM
We use lots of custom sheet copper busbars at work, for single-digit voltages.
The inductance of a busbar pair is minimized by running the metal strips face to face, separated only by a thin insulating sheet.
Unfortunately that maximizes the force tending to tear them apart from each other, in a quarter-shrinker application.
You can compute the magnitude of that Lorentz force when you have a reasonable guess about peak current.
For better accuracy, get set up to measure the inductance of assembled busbar pair. Repeat after increasing the separation. From dL/dx you can get the force for a given current, just like people do here to for coilguns.
klugesmith, Sun Feb 17 2019, 11:37PM
We use lots of custom sheet copper busbars at work, for single-digit voltages.
The inductance of a busbar pair is minimized by running the metal strips face to face, separated only by a thin insulating sheet.
Unfortunately that maximizes the force tending to tear them apart from each other, in a quarter-shrinker application.
You can compute the magnitude of that Lorentz force when you have a reasonable guess about peak current.
For better accuracy, get set up to measure the inductance of assembled busbar pair. Repeat after increasing the separation. From dL/dx you can get the force for a given current, just like people do here to for coilguns.
Re: Ring launcher optimum oscillator frequency
DerAlbi, Mon Feb 18 2019, 01:11AM
Ha, Uspring, i searched for my old work too, but since the forum is damaged, the whole thing is gone. Its a shame. Cant find it on my computer anymore.
But he would need Measurements of a fixed geometry already. From that he could however perfectly design the wire-thickness and with it the number of turns for his coil.
Again, its a shame the data is gone. (if its gone)
DerAlbi, Mon Feb 18 2019, 01:11AM
Ha, Uspring, i searched for my old work too, but since the forum is damaged, the whole thing is gone. Its a shame. Cant find it on my computer anymore.
But he would need Measurements of a fixed geometry already. From that he could however perfectly design the wire-thickness and with it the number of turns for his coil.
Again, its a shame the data is gone. (if its gone)
Re: Ring launcher optimum oscillator frequency
Signification, Mon Feb 18 2019, 01:45AM
This reminds me of a magnetic firing circuit I started to play with years ago. It is a bit similar to yours, but fires a non-ferrous HD platter in a VERY aerodynamic way--like a Frisbee. The firing coils are connected in and mounted on two stiff boards with the projectile sandwiched in between. The high current pulsed coils tend to greatly attract each other when fired (an annoying disadvantage). The disc is in between them, but slightly offset toward the firing direction. This lets the pulsed field lines from the coils (when triggered) 'wrap' or 'connect' slightly together behind the disc. When fired (pulsed) the field lines go around the disc (due to Eddy) and then the disc is projected outward like a Frisbee at great velocity as the lines -reconnect-. I think it is called a RE-CONNECTION pulse. To add to the aerodynamic efficiency, I was trying to think of a way to give the disc 'spin' as it emerged. Be careful, as this could fire at lethal manner. I have even seen the non-aerodynamic (THUMPER) types embed the disc deeply into wood.
Signification, Mon Feb 18 2019, 01:45AM
This reminds me of a magnetic firing circuit I started to play with years ago. It is a bit similar to yours, but fires a non-ferrous HD platter in a VERY aerodynamic way--like a Frisbee. The firing coils are connected in and mounted on two stiff boards with the projectile sandwiched in between. The high current pulsed coils tend to greatly attract each other when fired (an annoying disadvantage). The disc is in between them, but slightly offset toward the firing direction. This lets the pulsed field lines from the coils (when triggered) 'wrap' or 'connect' slightly together behind the disc. When fired (pulsed) the field lines go around the disc (due to Eddy) and then the disc is projected outward like a Frisbee at great velocity as the lines -reconnect-. I think it is called a RE-CONNECTION pulse. To add to the aerodynamic efficiency, I was trying to think of a way to give the disc 'spin' as it emerged. Be careful, as this could fire at lethal manner. I have even seen the non-aerodynamic (THUMPER) types embed the disc deeply into wood.
Re: Ring launcher optimum oscillator frequency
Uspring, Mon Feb 18 2019, 03:19PM
Oops, didn't see, that the attached files are inaccessible now. I saved a copy, though and can post it as ASCII text, which you can probably copy/paste, save as .asc file and then open with LTSpice. So if anyone is interested, I'll comply.
Does anybody know, if archive.org can be convinced to yield 4hv forum files?
Wrt to the optimal oscillation frequency: I believe it's best to match the first half cycle duration to the "takeoff" time of the disk. For Kizmos launcher, that time can be established from the simulation to be about 0.5ms, i.e. 1kHz. The force on the disk depends only on the energy stored in the coil, not its inductance. A too large inductance will take too long to charge up, so that the disk will have flown away before max current is reached. A too small inductance will cause unnecessary losses in the caps ESR and ESL.
Uspring, Mon Feb 18 2019, 03:19PM
Oops, didn't see, that the attached files are inaccessible now. I saved a copy, though and can post it as ASCII text, which you can probably copy/paste, save as .asc file and then open with LTSpice. So if anyone is interested, I'll comply.
Does anybody know, if archive.org can be convinced to yield 4hv forum files?
Wrt to the optimal oscillation frequency: I believe it's best to match the first half cycle duration to the "takeoff" time of the disk. For Kizmos launcher, that time can be established from the simulation to be about 0.5ms, i.e. 1kHz. The force on the disk depends only on the energy stored in the coil, not its inductance. A too large inductance will take too long to charge up, so that the disk will have flown away before max current is reached. A too small inductance will cause unnecessary losses in the caps ESR and ESL.
Re: Ring launcher optimum oscillator frequency
DerAlbi, Tue Feb 19 2019, 10:24AM
Well.. I would be interested for sure
Thanks for your data backup.
DerAlbi, Tue Feb 19 2019, 10:24AM
Well.. I would be interested for sure
Thanks for your data backup. Re: Ring launcher optimum oscillator frequency
Uspring, Tue Feb 19 2019, 11:21AM
I think it's a lovely little program. Since the LTSpice schematics (.asc) are simple ASCII texts, one should be able to import the text below into LTSpice. I had to modify it slightly, since the forum software doesn't like smaller and larger symbols.
Version 4
SHEET 1 2036 772
WIRE 1568 -256 1504 -256
WIRE 1504 -224 1504 -256
WIRE 1248 -176 1184 -176
WIRE 1184 -144 1184 -176
WIRE 1504 -112 1504 -144
WIRE 1008 -96 960 -96
WIRE 960 -64 960 -96
WIRE 1184 -32 1184 -64
WIRE 960 48 960 16
WIRE -304 80 -352 80
WIRE 448 80 400 80
WIRE 720 80 528 80
WIRE 816 80 720 80
WIRE -32 96 -64 96
WIRE 0 96 -32 96
WIRE 400 112 400 80
WIRE 816 144 816 80
WIRE -352 176 -352 80
WIRE -64 176 -64 96
WIRE 720 192 720 160
WIRE -704 208 -704 96
WIRE -64 272 -64 256
WIRE 400 272 400 176
WIRE 720 272 720 256
WIRE 816 272 816 224
WIRE -352 288 -352 256
WIRE -704 304 -704 288
WIRE 1120 384 1056 384
WIRE 1056 416 1056 384
WIRE 1056 528 1056 496
FLAG 400 272 0
FLAG 816 272 0
FLAG -352 288 0
FLAG -304 80 Inductance
FLAG -704 96 K
FLAG -704 304 0
FLAG 960 48 0
FLAG 1008 -96 Force
FLAG 1184 -32 0
FLAG 1248 -176 Velocity
FLAG 1504 -112 0
FLAG 1568 -256 Distance
FLAG 720 272 0
FLAG 1056 528 0
FLAG 1120 384 Efficiency
FLAG -64 272 0
FLAG -32 96 InductanceChange
SYMBOL cap 384 112 R0
SYMATTR InstName C1
SYMATTR Value {C} ic={CapVoltage}
SYMBOL res 432 96 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R1
SYMATTR Value {ESR}
SYMBOL bv -352 160 R0
SYMATTR InstName B2
SYMATTR Value V=L0*(1-V(K)**2)
SYMBOL bv 816 128 R0
SYMATTR InstName B1
SYMATTR Value V=V(Inductance)*ddt(I(B1)) + I(B1)*V(InductanceChange)
SYMBOL bv -704 192 R0
WINDOW 3 -44 159 Left 2
SYMATTR Value V=0.63238*2.718281828**(V(Distance)*-0.0305072k)
SYMATTR InstName B3
SYMBOL bv 960 -80 R0
SYMATTR InstName B4
SYMATTR Value V=max(0.5*V(InductanceChange)/(V(Velocity)+1m) *I(B1)**2, 0)
SYMBOL bv 1184 -160 R0
SYMATTR InstName B5
SYMATTR Value V=max(idt(V(Force)/DiskMass), 0)
SYMBOL bv 1504 -240 R0
SYMATTR InstName B6
SYMATTR Value V=max(idt(V(Velocity)), 0)
SYMBOL diode 736 256 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D1
SYMATTR Value DIdeal
SYMBOL res 736 64 M0
SYMATTR InstName R2
SYMATTR Value {ESR*2}
SYMBOL bv 1056 400 R0
SYMATTR InstName B7
SYMATTR Value V=DiskMass*V(Velocity)**2 / (C*CapVoltage**2)
SYMBOL bv -64 160 R0
SYMATTR InstName B8
SYMATTR Value V=ddt(V(Inductance))
TEXT -232 -288 Left 2 !.param C = 94m
TEXT -232 -256 Left 2 !.param CapVoltage = 450
TEXT -232 -224 Left 2 !.param ESR = 10m
TEXT -232 -192 Left 2 !.param L0 = 8u
TEXT 312 472 Left 2 !.tran 0 5m 0 0.1u uic
TEXT -232 -152 Left 2 !.param DiskMass = 0.2
TEXT 376 16 Left 2 !.model Dideal D(Ron=0.1m Roff=1G Vfwd=0.4)
TEXT -248 -368 Left 6 ;Adjust Parameters
TEXT 832 -376 Left 6 ;Interesting
TEXT 1280 -216 VLeft 6 ;==
TEXT -1640 176 Left 6 ;Curve-Fitting for K in \ndependence of the \n"V(Distance)" im m
TEXT -904 352 Left 6 ;==
TEXT 1448 408 Left 6 ;Interesting
TEXT 1288 408 Left 6 ;==
TEXT 128 -288 Left 2 ;Capacity
TEXT 128 -256 Left 2 ;CapBank voltage
TEXT 128 -224 Left 2 ;Overall ESR
TEXT 128 -192 Left 2 ;Inductance without any Disk
TEXT 128 -160 Left 2 ;in kg
TEXT -248 -56 Left 2 ;.step param ESR 10m 190m 10m
TEXT -248 -88 Left 3 ;Step Parameter to check influence
TEXT 1016 -128 Left 2 ;in N
TEXT 1280 -144 Left 2 ;in m/s
TEXT 1592 -224 Left 2 ;in m
TEXT 856 256 Left 2 ;Learned from Uspring.
TEXT 984 48 Left 2 ;Learned from Uspring.
Uspring, Tue Feb 19 2019, 11:21AM
I think it's a lovely little program. Since the LTSpice schematics (.asc) are simple ASCII texts, one should be able to import the text below into LTSpice. I had to modify it slightly, since the forum software doesn't like smaller and larger symbols.
Version 4
SHEET 1 2036 772
WIRE 1568 -256 1504 -256
WIRE 1504 -224 1504 -256
WIRE 1248 -176 1184 -176
WIRE 1184 -144 1184 -176
WIRE 1504 -112 1504 -144
WIRE 1008 -96 960 -96
WIRE 960 -64 960 -96
WIRE 1184 -32 1184 -64
WIRE 960 48 960 16
WIRE -304 80 -352 80
WIRE 448 80 400 80
WIRE 720 80 528 80
WIRE 816 80 720 80
WIRE -32 96 -64 96
WIRE 0 96 -32 96
WIRE 400 112 400 80
WIRE 816 144 816 80
WIRE -352 176 -352 80
WIRE -64 176 -64 96
WIRE 720 192 720 160
WIRE -704 208 -704 96
WIRE -64 272 -64 256
WIRE 400 272 400 176
WIRE 720 272 720 256
WIRE 816 272 816 224
WIRE -352 288 -352 256
WIRE -704 304 -704 288
WIRE 1120 384 1056 384
WIRE 1056 416 1056 384
WIRE 1056 528 1056 496
FLAG 400 272 0
FLAG 816 272 0
FLAG -352 288 0
FLAG -304 80 Inductance
FLAG -704 96 K
FLAG -704 304 0
FLAG 960 48 0
FLAG 1008 -96 Force
FLAG 1184 -32 0
FLAG 1248 -176 Velocity
FLAG 1504 -112 0
FLAG 1568 -256 Distance
FLAG 720 272 0
FLAG 1056 528 0
FLAG 1120 384 Efficiency
FLAG -64 272 0
FLAG -32 96 InductanceChange
SYMBOL cap 384 112 R0
SYMATTR InstName C1
SYMATTR Value {C} ic={CapVoltage}
SYMBOL res 432 96 R270
WINDOW 0 32 56 VTop 2
WINDOW 3 0 56 VBottom 2
SYMATTR InstName R1
SYMATTR Value {ESR}
SYMBOL bv -352 160 R0
SYMATTR InstName B2
SYMATTR Value V=L0*(1-V(K)**2)
SYMBOL bv 816 128 R0
SYMATTR InstName B1
SYMATTR Value V=V(Inductance)*ddt(I(B1)) + I(B1)*V(InductanceChange)
SYMBOL bv -704 192 R0
WINDOW 3 -44 159 Left 2
SYMATTR Value V=0.63238*2.718281828**(V(Distance)*-0.0305072k)
SYMATTR InstName B3
SYMBOL bv 960 -80 R0
SYMATTR InstName B4
SYMATTR Value V=max(0.5*V(InductanceChange)/(V(Velocity)+1m) *I(B1)**2, 0)
SYMBOL bv 1184 -160 R0
SYMATTR InstName B5
SYMATTR Value V=max(idt(V(Force)/DiskMass), 0)
SYMBOL bv 1504 -240 R0
SYMATTR InstName B6
SYMATTR Value V=max(idt(V(Velocity)), 0)
SYMBOL diode 736 256 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D1
SYMATTR Value DIdeal
SYMBOL res 736 64 M0
SYMATTR InstName R2
SYMATTR Value {ESR*2}
SYMBOL bv 1056 400 R0
SYMATTR InstName B7
SYMATTR Value V=DiskMass*V(Velocity)**2 / (C*CapVoltage**2)
SYMBOL bv -64 160 R0
SYMATTR InstName B8
SYMATTR Value V=ddt(V(Inductance))
TEXT -232 -288 Left 2 !.param C = 94m
TEXT -232 -256 Left 2 !.param CapVoltage = 450
TEXT -232 -224 Left 2 !.param ESR = 10m
TEXT -232 -192 Left 2 !.param L0 = 8u
TEXT 312 472 Left 2 !.tran 0 5m 0 0.1u uic
TEXT -232 -152 Left 2 !.param DiskMass = 0.2
TEXT 376 16 Left 2 !.model Dideal D(Ron=0.1m Roff=1G Vfwd=0.4)
TEXT -248 -368 Left 6 ;Adjust Parameters
TEXT 832 -376 Left 6 ;Interesting
TEXT 1280 -216 VLeft 6 ;==
TEXT -1640 176 Left 6 ;Curve-Fitting for K in \ndependence of the \n"V(Distance)" im m
TEXT -904 352 Left 6 ;==
TEXT 1448 408 Left 6 ;Interesting
TEXT 1288 408 Left 6 ;==
TEXT 128 -288 Left 2 ;Capacity
TEXT 128 -256 Left 2 ;CapBank voltage
TEXT 128 -224 Left 2 ;Overall ESR
TEXT 128 -192 Left 2 ;Inductance without any Disk
TEXT 128 -160 Left 2 ;in kg
TEXT -248 -56 Left 2 ;.step param ESR 10m 190m 10m
TEXT -248 -88 Left 3 ;Step Parameter to check influence
TEXT 1016 -128 Left 2 ;in N
TEXT 1280 -144 Left 2 ;in m/s
TEXT 1592 -224 Left 2 ;in m
TEXT 856 256 Left 2 ;Learned from Uspring.
TEXT 984 48 Left 2 ;Learned from Uspring.
Re: Ring launcher optimum oscillator frequency
DerAlbi, Tue Feb 19 2019, 11:30AM
Thank you. Putting it into a Text-File and renaming it to .asc works. The fact that the coupling factor is curve-fitted in the model is a bit user-unfriendly. Should have used a table lookup.
DerAlbi, Tue Feb 19 2019, 11:30AM
Thank you. Putting it into a Text-File and renaming it to .asc works. The fact that the coupling factor is curve-fitted in the model is a bit user-unfriendly. Should have used a table lookup.
Re: Ring launcher optimum oscillator frequency
Signification, Wed Apr 17 2019, 07:20AM
Maybe something n here will help:
Signification, Wed Apr 17 2019, 07:20AM
Maybe something n here will help:
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