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/diy/ - Do-It-Yourself


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1628028 No.1628028 [Reply] [Original] [archived.moe]

Not sure if this belongs on /k/ or not

what's the best way to make the current running through the coil stop when the slug is halfway through so it keeps its momentum. A Laser? any other, better ideas

>> No.1628051

a switch

>> No.1628067

Put an accelerometer on the bullet, when it senses it reaches the middle of the coil, simply turn the coil off.

>> No.1628084

EE anon here. First off, stopping a current running i a coil is not instatenious. I guess your unloading capacitors over the coil to get a high magnetic field. Timing is important here... Get a sensing coil which is only a couple of turns between your coils that you energize. The projectile should have such a shape that when its almost in the middle of the coil, the tip of the projectile is already in the sensing coil inducing a current into it. Then let this induced current trigger a mosfet/triac whatever that will interupt current flowing into the coil. Its basically like a linear transformer, you induce current through magnetic field in projectile, then from projectile into sensing coil that will close current to previous coil and open capacitor to next one. You need to use ferro magnetic material on projectile.

>> No.1628360

A button. The slug hits button, power goes away.

>> No.1628366

>>1628028
Use a metal sabot to carry your projectile, or, let the metal projectile itself, be part of the circuit, by making contact between two metal rails. Half way down, rails stop being metal or disappear entirely. Current stops the instant the projectile passes that point. You can design the coil gun so the heavy current flowing the projectile / sabot can even induce a stronger magnetic field to increase efficiency.

>> No.1628393

Isn't it called a railgun.

>> No.1628404

>>1628028
hall sensor and transistor as a switch

>>1628393
No, a railgun provides a continuous current through he projectile in a magnetic field to accelerate the projectile.

>> No.1628488

>>1628366
Hmmmm.... I was thinking of a railgun when I posted this.... Now that I look at OP's diagram again.... he has multiple coils, and yes, a metal projectile at the halfway point would be "stuck" so you would want to cut the field probably just before that? Not sure exactly at what point we would have maximum acceleration on the projectile. Current would be essentially switched to the next coil assuming ideal coil arrangement so that the projectile is just within the "grabbing" range of the next coil when it is passing the shut off point of the previous coil. Here's a question for physics nerds: When shutting off the current what sort of back-EMF effects are we going to see and how do they affect the projectile?

>> No.1628523

>>1628028
>A Laser
a diode photocell should do the job
typically you'd want a photocell at the beginning of each coil and switch off the current when the projectile has passed the photocell + a delay.
You have to do a lot of trial for the right delay time

>> No.1628623

>>1628084
Based

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