Re: Silicon Controlled Rectifier
 

k thanxs for your help:) i really appreciate it.

another quick question. Me and another student are having a heated argument over how long the barrel of the tube should be. Saying we have a four foot tube, my suggestion was to cut it in half. This way the three coils are kept close together and has a stronger punch at the beginning.

On the other hand he suggests we use the entire four feet of tubing to gain a greater momentum.

my question is. For this type of experiment, would the projectile travel faster in a short tube with the coils close together, or longer tube spread out?


by saying this, keep in mind that our robot is only 2 feet wide, 1 (1/2) feet long.

Re: Silicon Controlled Rectifier
 

Bah, I just TAed a class that made coil guns. You'd think I'd know the answer off the top of my head... Make Greg Marra answer this. He was actually taking the class, I was just sorta teaching it.

My bet is that single coil would be a heck of a lot easier to do timing on.

DO BOTH!

Enjoy, and Good Luck!

Re: Silicon Controlled Rectifier
 

Short tube, definitely. Your friend is probably thinking about explosively powered projectile weapons. In those cases, the additional barrel length allows the projectile to gain kinetic energy from the expanding gas for a longer period of time. In a coil gun, all that extra barrel length does is slow the projectile down due to friction from contact with the barrel. A longer barrel may help with accuracy somewhat, but you'd likely get similar improvement from rifling the barrel and using aerodynamic projectiles. One thing is for sure though, in a coil gun more barrel length will not increase the projectile's momentum. BTW, at school you may want to call this a 'Solenoid-based Electromagnetic Linear Accelerator' instead of a 'coilgun'... I don't know how uptight the administration is about weaponry in your school, but it might avoid some potential problems.

Re: Silicon Controlled Rectifier
 

Ye i thought so as well with the short tube. shorter tube = less friciton.


Ye and our school is pretty strict. We were gonna call it MAC (Magnetic Accelerator Cannon).

Alrighty. We thanks alot everyone for your support. I'll be making a few more posts towards the end of november. I'll tape some of our experiments and if your interested, PM me for a couple of videos :)

Im starting up a ProcessLocal() thread in programming within a week once i learn about interrupts. Feel free to post :)

Re: Silicon Controlled Rectifier
 

Hey guys im back with more questions :D

first question. is it possible to hook up two 6A diodes in parallel to get a total diode protection of 12A?

second question. if a bridge rectifer is rated for 25A, does that mean i have to put 25A through the rectifer for it actaully work?>?

Thanxs again..

if the question seems confusing, let me noe.

Re: Silicon Controlled Rectifier
 

1st: two 6A diodes in parallel will not share current perfectly, so their total capacity will be less than 12A. Also, the Ampere rating of a diode is generally tied to an assumed operating temperature; if actual temperature is higher then the diode will fail at less than its nominally rated Amperes.

2nd: the 25A rating on your rectifier is a maximum (again, at the given temperature, which is usually 25 Celsius) -- you can operate the bridge at lower current.

Re: Silicon Controlled Rectifier
 

Hello everyone.

another question for my little project.

http://www.canadiantire.ca/browse/pr...08474396672500

this inverter supplys 120 VAC @ 300 watts (2.5A)

my question is, since there are two outputs, would it be possible to hook these in parallel to acheive a 120VAC @ 600 watts (5A)?

Re: Silicon Controlled Rectifier
 

No, there are two outputs are in parallel for convenience. One must be careful when looking at AC inverters. Often they do not put out pure sine waves. They may be modified sine wave or they are sometimes quasi square waves. Use caution when feeding transformer inputs like power supplies as the unusual input waveform may cause core heating in the transformer.