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Registered Member #1694
Joined: Sat Sept 13 2008, 09:13AM
Location: Australia
Posts: 108
Hi,
After weeks of sitting in front of my computer and stealing ideas of other people, I've finally finished designing the electronics part of a 250J coilgun rifle. I'm going for portability and efficiency (just like everyone else).
This gun will have 5 coil stages + an injector coil, and fire 3 gram slugs. Charge time *hopefully* will be around 3 seconds. It uses v switches and I plan on using iron powder and epoxy when I make the coils. The capacitor sizes and coil inductance & resistance has all been calculated for optimum efficiency - no guess work in this one. I'm HOPING for 5% efficiency. But I'd be happy with 2.5%.
Registered Member #1819
Joined: Thu Nov 20 2008, 04:05PM
Location:
Posts: 137
Camel wrote ...
Hi,
After weeks of sitting in front of my computer and stealing ideas of other people, I've finally finished designing the electronics part of a 250J coilgun rifle. I'm going for portability and efficiency (just like everyone else).
This gun will have 5 coil stages + an injector coil, and fire 3 gram slugs. Charge time *hopefully* will be around 3 seconds. It uses v switches and I plan on using iron powder and epoxy when I make the coils. The capacitor sizes and coil inductance & resistance has all been calculated for optimum efficiency - no guess work in this one. I'm HOPING for 5% efficiency. But I'd be happy with 2.5%.
Charge time: I would aim for for a second or much less. The flyback converter you are using (and even the simple NE555 boost converter) can achieve this charging rate with a simple optimization of operating frequency (in relation to the inductor's peak current). For some reason, I can't open the image of your schematic, and I don't know the inductance of your flyback, so I can't give you the frequency.
Efficiency: Make sure your capacitor bank and coil combination isn't critically damped, since this reduces efficiency greatly and drastically lowers the peak current out of your capacitors. And if you're hoping for a high efficiency, hope for 10%. 5% should be your goal.
Registered Member #1694
Joined: Sat Sept 13 2008, 09:13AM
Location: Australia
Posts: 108
killah573 wrote ...
Camel wrote ...
Hi,
After weeks of sitting in front of my computer and stealing ideas of other people, I've finally finished designing the electronics part of a 250J coilgun rifle. I'm going for portability and efficiency (just like everyone else).
This gun will have 5 coil stages + an injector coil, and fire 3 gram slugs. Charge time *hopefully* will be around 3 seconds. It uses v switches and I plan on using iron powder and epoxy when I make the coils. The capacitor sizes and coil inductance & resistance has all been calculated for optimum efficiency - no guess work in this one. I'm HOPING for 5% efficiency. But I'd be happy with 2.5%.
Charge time: I would aim for for a second or much less. The flyback converter you are using (and even the simple NE555 boost converter) can achieve this charging rate with a simple optimization of operating frequency (in relation to the inductor's peak current). For some reason, I can't open the image of your schematic, and I don't know the inductance of your flyback, so I can't give you the frequency.
Efficiency: Make sure your capacitor bank and coil combination isn't critically damped, since this reduces efficiency greatly and drastically lowers the peak current out of your capacitors. And if you're hoping for a high efficiency, hope for 10%. 5% should be your goal.
I have yet to build it, but Uzzor was getting 50watts out of his mazzili charger, and that was at 12V. I'm running mine at 24V, so I figured 100watts would be a good estimate. I have yet to see a coilgun which is 10% efficient. I thought 5% would be impressive xD
Registered Member #1774
Joined: Wed Oct 22 2008, 02:51AM
Location:
Posts: 135
I agree that 5% is a resonable goal, thats still 12.5j muzzle energy, which is more than an average air rifle. It would be nice for you to acheive 10%, but I guess we will see when you are finished.
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250J Coilgun
