calling smart people...cap install question

[Bfowler]

not trying to start a debate as to their usefulness...my question is why is this
the correct way to install them?



it seems that that would essentially "bypass" the cap


why dont you install it: 12v > cap+ > cap- > amp? so the currant goes "through" the cap?

[Stryker]

going from your diagram, I do not ground the amp and cap separately. i do the ground from amp through the cap, essentially the way that you wrote it out. i read somewhere that having just the one main ground is better in reducing noise and possibly a ground loop issue. i've never had a problem this way.

[todd217]

not if you imagine the cap as a second battery.

[Bfowler]

i guess it makes sense that way.


so what would happen if you wired the 12+ into the positive, then out of the - and to the amp?

[waynehead]

a Haitian baby dies.



Sorry, too soon?

[Bfowler]

so we have figured out that wiring caps wrong causes AIDS.

[ttocs]

I think it would be nothing more then an ac filter when used in series like that but then I thought that was one argument that was supposed to be a positive for caps even when put in parallel. I think that even just having one in the package in the trunk is supposed to help and give a couple of HP.

[todd217]

caps can explode and catch fire if not hooked up right.

[davewaibel]

carbon caps won't explode, not work well, but they can take a pretty 'oops' with little fire works-

[finbar]

Perry Babin has a good site,

http://www.bcae1.com/capacitr.htm

[Bfowler]

i read that!


i guess what i dont understand is why on a electrical level, the currant chooses to "use" the cap, instead of bypassing it altogether since the + wire is essentially a wire going straight across the cap

[Eric D]

If you take a cap apart you find all it is are a pair of electrical conductors which sit NEXT to each other. They do not touch each other. The larger the conductors are and the closer they are to each other, the more charge builds up on them.

Since they are not touching, no current (DC) will flow from one to the other. If you put the cap in series with your amps power terminal, it would not get any current. The amp would read 0V at the 12V terminal.

Wires have capacitance. If you use parallel speaker wires (often called "zip cord"), they have capacitance. Your 0ga power wire sitting next to your 0ga ground wire has capacitance. But, both these items have very little capacitance.

All this changes with AC. With AC, signals can pass from one conductor to the other. They don't actually jump across, but they are "agitated" internally to form on the opposite terminal.

[Bfowler]

ah, i think i'm starting to get it! thanks!

[ttocs]

I saw enough of the little caps pop in tech school to know that I did not want to be anywhere near a 1F if it ever went. I can remember a fairly descent little cap going with enough fource that we found the metal cap from the top stuck in the ceiling tile. Has anyone actually seen anything like a 1/2F or bigger blow? They have the hole in them to help it from exploding but always wondered....

[Eric D]

I had heard a 1F was equivalent to 1/4 stick of dynamite as far as blowing up. But, this was more an urban myth than anything else.

I wonder if the Mythbusters would be willing to try shorting and blowing up some 1F caps to see how dangerous they actually are?

[ttocs]

maybe if someone posts it and we all go on and hit the post. 1/4 stick shit man that will make your ears ring. Down in Az that is what the mexicans call fireworks and it will make you jump even if you do expect it. As I said I remember what the little ones would do and they would make a good pop also.

[smgreen20]

Back in '96 a friend of mine took my 1.2F cap into electronics class as the teacher stated he had never SEEN one that big before. He asked my friend to take it back out to the car right then and there. I guess he was afraid of it.

Might have to youtube it.

[ttocs]

it occured to me I have found a video for everything on youtube including mrs garret holding a bong so why not this.

here is the little ones and I have seen these personally. We have seen what can happen to the circuit boards they are mounted to.

http://www.youtube.com/watch?v=_WheLp0RdLQ

little bigger

http://www.youtube.com/watch?v=ToWsF3Hc ... ature=fvwp

not sure about this one

http://www.youtube.com/watch?v=WDVdJMdD ... o_response

[audiophyle_247]

Look at the amount of voltage it takes to blow up a cap compared to what it sees in everyday usage.

Explosion due to over-voltage is next to impossible in a vehicle.
ttocs, the last vid they wired 4 batts in series to push 50v to the cap.

[stipud]

Look at the amount of voltage it takes to blow up a cap compared to what it sees in everyday usage.

Explosion due to over-voltage is next to impossible in a vehicle.
ttocs, the last vid they wired 4 batts in series to push 50v to the cap.

It was a 63v cap though. The reason it blew is because it was hooked up backwards. You could definitely do that in a car. Fortunately I have heard of many people doing that and no cases of explosions yet.

[audiophyle_247]

Didnt read the whole thing, just the few comments. Thought they had sent 50v to a 12v cap.

A car battery can do the same thing if hooked up backward, so should we stop using them too? Many things can be very dangerous if installed backward or incorrectly, but how many caps have failed when everything is correct?

[ttocs]

I am not saying they are safety hazards just posting what I saw after wondering what a 1F would look like. I have never seen anything happen to a big one and seen plenty of people slap-charge them and do all kinds of other stupid stuff.........