# rail gun question

Discussion in 'General Electronics' started by sean, Sep 13, 2003.

1. ### seanGuest

Hi, I'm attempting to build a rail gun. I have 3 capacitors, each are
150VDC 4mF. My question is, should I connect them in series or
parallel? I might be able to build an AC to DC transformer that
triples voltage. Thanks.

2. ### JeffMGuest

Hi, I'm attempting to build a rail gun. I have 3 capacitors, each are
150VDC 4mF. >...should I connect them in series or parallel?
You're going to have to give us a better hint what you're up to.
An ASCII diagram might help.
In series you have 450V 1.33uF; in parallel it's 150V 12uF.

3. ### seanGuest

ok, the thing is I don't know which way would best power a rail gun.
I saw a website with a 4.2mF 450V capacitor. I'm thinking I'll just
go with 150V (charge from a wall outlet and diode bridge) and see what
I can do. Any other ideas are appreciated

I have a diode bridge, but it goes from ac 120V to dc 110V. Anyone
know why that is?

I have an 800uF capacitor (200V) I would like to filter the signal
with. Is it ok to connect it in parallel to the ac current, or will
it ruin it to charge it the "wrong" way. If it's ok, I need to make
sure it takes at least 1/120th of a second to charge, right? Anyone
know the formula? That way I will be able to tell what size resistor
I will need. Thanks.

4. ### seanGuest

ok thanks, I couldn't get it to work as a rail gun, I'm attempting a
coil gun instead. I have been charging it for about 1-2 mins, could
the capacitors explode since they are 150v capacitors and peak voltage
is 170?

thanks

5. ### JeffMGuest

Yes. That's the point.

6. ### AndreGuest

The OP should use a proper DC regulated supply to ensure that the
capacitor voltage never goes above the PV of the capacitors .

-A

7. ### JeffMGuest

Yes, and everyone should drive a Benz because they're engineered so well.

Wake up and step into the real world.

8. ### David HarperGuest

<snip>

A rail gun? Stop me if I'm wrong, but you'll need some more than just
caps. Specifically, if I'm thinking of the same type of rail gun you
are, you'll be needing some electromagnets, optical counters/sensors,
etc...?

Dave