Planning a 2 stage Coil gun / Electromagnetic Projectile Accelerators / Forums

Forums

4hv.org :: Forums :: Electromagnetic Projectile Accelerators

« Previous topic | Next topic »

Planning a 2 stage Coil gun

Move Thread

LAN_403

ZakWolf

Sat Jan 05 2013, 08:47AM

Registered Member #3114 Joined: Sat Aug 14 2010, 08:33AM
Location:
Posts: 608

***I am going to start planning a project, I want to make a coil gun with two stages, i think i have had good results with past single stage coil guns pushing 288j.

I want to have 2 coils, one being a bank of 288j and the "injector coil" being 144 joules.

The only thing that is stopping me from starting is i cant find an optical trigger circuit for my coil gun, could someone give me a tested or preferred circuit...

thanks a million***

Didnt want to make a new thread:

I am using these calculators on Barry's Coilguns page

My questions are:

1)if i use this optic trigger here (the first one) should i put it as close as possible to the second coil (just before) since if i read it correctly the trigger time is very fast.

2)Im going to make the second coil a cm shorter then the first and powered by half the strength of the first one( first coil has 244j and the second one for the final kick has 144j) does this sound like it should work ok ?

PSCG

Sat Jan 05 2013, 10:40AM

Registered Member #3792 Joined: Sun Mar 27 2011, 06:07PM
Location:
Posts: 136

Check this good discussion. It gives a lot of info about simple optical triggering.

You could also use this circuit (under the "Projectile Detection" link). If you want a sharp output pulse, connect it's output to a 555 monostable and you will get your desired output pulse duration.

ZakWolf

Sat Jan 05 2013, 11:10AM

Registered Member #3114 Joined: Sat Aug 14 2010, 08:33AM
Location:
Posts: 608

PSCG wrote ...

Check this good discussion. It gives a lot of info about simple optical triggering.

You could also use this circuit (under the "Projectile Detection"). If you want a sharp output pulse, connect it's output to a 555 monostable and you will get your desired output pulse duration.

Thanks for the reply but both links dont seem to work

PSCG

Sun Jan 06 2013, 10:03AM

Registered Member #3792 Joined: Sun Mar 27 2011, 06:07PM
Location:
Posts: 136

Oh, it seems that my browser bugged while i was writing the reply. I corrected the first one so you can try again now. Sorry for that. The second one works for me. It opens a seemingly blank page but you can click on the links on the top of the page and will show the contents.

ZakWolf

Sun Jan 06 2013, 10:16AM

Registered Member #3114 Joined: Sat Aug 14 2010, 08:33AM
Location:
Posts: 608

PSCG wrote ...

Oh, it seems that my browser bugged while i was writing the reply. I corrected the first one so you can try again now. Sorry for that. The second one works for me. It opens a seemingly blank page but you can click on the links on the top of the page and will show the contents.

Thanks the first linked worked but the second said"no 4hv allowed" O.o

I will do some more research thanks for the point in the right direction

ZakWolf

Mon Jan 07 2013, 06:43AM

Registered Member #3114 Joined: Sat Aug 14 2010, 08:33AM
Location:
Posts: 608

If I use the optical trigger mention in the first post, what kind of LED do i need? a regular led or an infrared?

PSCG

Mon Jan 07 2013, 02:25PM

Registered Member #3792 Joined: Sun Mar 27 2011, 06:07PM
Location:
Posts: 136

Weird, the link works for me and i tested it from multiple computers.

There is no reason for it not to work with a normal LED. Infrared LED's are a bit less prone to interference from usual light sources (although it does exist - i have come across this problem before). I have seen some coilgun projects use simple 640 nm laser pointers for detection with no problem.

Yes, position the optical trigger just before the entrance of the second coil. You might need to make some small adjustments to get the timing right (moving the sensor some mm before the coil's entrance).

Usual configuration for an "injector + accelerator" coilguns is a low power injector stage followed by the main accelerator (higher power) stage. But you can try your configuration and see what is the best for you. Later, you can easily swap them.

This is the image from the first link:

Detection1

Have success with your project!

ZakWolf

Mon Jan 07 2013, 03:29PM

Registered Member #3114 Joined: Sat Aug 14 2010, 08:33AM
Location:
Posts: 608

PSCG wrote ...

Weird, the link works for me and i tested it from multiple computers.

There is no reason for it not to work with a normal LED. Infrared LED's are a bit less prone to interference from usual light sources (although it does exist - i have come across this problem before). I have seen some coilgun projects use simple 640 nm laser pointers for detection with no problem.

Yes, position the optical trigger just before the entrance of the second coil. You might need to make some small adjustments to get the timing right (moving the sensor some mm before the coil's entrance).

Usual configuration for an "injector + accelerator" coilguns is a low power injector stage followed by the main accelerator (higher power) stage. But you can try your configuration and see what is the best for you. Later, you can easily swap them.

This is the image from the first link:

Detection1

Have success with your project!

Thanks for the feed back i just have a couple more questions.

I would like to use this trigger circuit

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob