shane12286

i was wondering the best way to wire up a capacitor.. i have a 1 farad with digital cap.. i had it hooked up and didnt notice much differnce in power or dimming lights.. i lost the resistor used when charging it.. what kind should i use? i have resistors used with my LED's that look the same as the one it came with will those work? thank you

image

iTrader: (6)

I would ONLY use the resistor that it comes with. This thing is a real battery and CAN explode. I would not take it lightly. When i make any minor changed to my power wire, I uncharge my cap and unhook my battery. Consult your company that you bought it from to see what they say. REMEMBER THIS IS A REAL BATTERY!! We had a discussion on a sg forum about it blowing up like a pipe bomb.... Good luck.

friendhasmax

a "REAL BATTERY!!!!" ??? where the heck do you get your information from man? a capacitor is in no way, shape, or form, a battery. If you have no idea what you are talking about then just say so, or don't bother posting. This is the exact reason why people on the internet are so mis-informed about things like this. you can use a different resistor if you want to. in fact, you don't need to use a resistor at all. all you need is a 12V light bulb in line with the power wire. i preferr the light bulb method since you dont have to monitor the cap with a volt meter like when you use the resistor method. all you have to do is wait for the light to go out, thats how you know the cap is done charging. i have yet to ever see or hear of a cap blowing up like a pipe bomb. the worst that would happen is it would leak. if you do use a resistor, use 1/2 watt resistor (100 ohms) should be fine. remember that when charging through a resistor and monitoring it's voltage with the volt meter, that as the voltage increases it increases at a slower rate, so don't be alarmed that it's taking a while...this is just how they charge/discharge. and if you want to get technical, they never fully charge are discharge, but they get very close to it.

ToTheMax_77

+1 with friendhasmax

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iTrader: (6)

Im getting my information of of the streetglow message board. From what i thought it was accurate. I appologize if it wasn't......

friendhasmax

its ok.......

Luquire

Though a capacitor can pop and sort of blow up (I have dont this with a 2500 micro farad electrolitic capacitor) but i dont see it being a danger. I did this in the electronics lab when i was in college. It smelled bad but nothing major. Also the hever charging and never discharging that was talked about is called cliping. the capacitor is considered a voltage source that comes on when there is a drop in the voltage (i.e. AC power). With AC power it keep the power much more linear. It sort of straightens out the Sinusoidal wave.(sort of) This clipping could happen when your system hits really hard or something that causing a dip in the voltage. The the capacitor has a draw on it which makes it release some of its stored energy (e.g. battery) at a certain rate which helps to slow the sudden drop in current until the battery and alternator can recover. The only major thing that could go wrong with the capacitor is either it shorting out and killing you (yes if it has a high enough capitance it can kill) and it popping and maybe blowing up. It is definately not a wet battery like the one in our cars. You are not going to get acid on you or anything crazy like that. I mean it is a solid battery so it could exploid but the only thing that might hurt you is a small piece of metal.

friendhasmax

here we go again:

"I mean it is a solid battery so it could exploid but the only thing that might hurt you is a small piece of metal."

NO! IT IS NOT A BATTERY OF ANY SORT!!!!

"Also the hever charging and never discharging that was talked about is called cliping."

THIS IS NOT CLIPPING. CAPACITOR CHARGING/DISCHARGING IS MATHEMATICALLY AN EXPONENTIAL GROWTH/DECAY FUNCTION. IT CHARGES UP
TO THE SAME VOLTAGE AS THE SOUCE VOLTAGE ASYMPTOTICALLY (MEANING IT APPROACHES THE SOURCE VOLTAGE BUT NEVER ATTAINS IT....SAME WITH DISCHARGING...IT WILL ASYMPTOTICALLY REACH ZERO VOLTS BUT NEVER ACTUALLY GET THERE.

FREAKIN CLIPPING? WHAT IS GOING ON IN YOUR HEAD? THIS HAS NOTHING TO DO WITH CLIPPING. AND AC?? NO ONE IS SPEAKING OF CAPACITORS IN AC CIRCUITS...THIS DISCUSSION IS ABOUT DC. CAPACITORS DO NOT STORE ENERGY IN AC CIRCUITS LIKE THEY DO IN DC. DAMMMMMMNNNNNN!!!!!!

I HATE GOING OVER THIS CRAP OVER AND OVER AND OVER!!

Luquire

I know all about the timing function of e^1/(tau*c). so dont think i am talking out of my A$$.

Maxima Dan

Why would the cap explode when you hook it to a car battery. I could see if you were going over the 80V threshold for that cap, but not at 12. A cap is meant to charge and discharge, it's what they do. For a 1F cap I never even bother to charge them before installing them and have yet to have a problem. I could see if you were installing 4 or 5F worth of caps, then I would understand bringing them up to 12V slowly would protect the fuses and battery (car battery, don't flame).

Now If you insist on using the resistor method all you need to do is calculate the proper R value. Going back to electronics 101 P=IV and V=IR; therefore P=V^2/R. Now figure the resistor will initially see the full 12V as the cap will act as a short at first, so for a 1/2 Watt resistor .5W=12^2/R. Solving for R you get R=288 Ohms. I would make sure you use a 1/2 Watt resistor that is at least 300 Ohms or you will really burn your fingers trying to hold that resistor.

BTW double check my math, it's been a long time since I used this stuff.

Maxima Dan

Did you ever discharge it? If not it probably still has a charge on it.

Luquire

Can you discharge a capacitor by placing a load speaker) on it without there being any power source(i.e. car battery) or do you just let it discharge over time after unplugging it.

Maxima Dan

Don't use a speaker as a load. But, yes, that would discharge the cap. Just kinda expensive if it goes wrong. Again I would use a 300-500 Ohm 1/2W resistor. But I have also used wrenches, screwdrives, the chassis of my car, etc. I don't recommend any of those either, but they do work.

raga55

Not to break up this technical discussion here, but i think shane12286 was just asking how to hook up his cap properly. Now all this technical info on how they work is great but some just tell this guy if he hooked his cap up right or not.

friendhasmax

you have no idea what you are talking about. if you actually knew what you were talking about, you would have never mentioned nonsense about clipping and AC voltages. i have every right to say you are talkig out of your a$$ because your post was WAYYYYY off base.

Luquire

Here is a definition that i found
"Clipping
A signal that results from an amplifier that is either overloaded or underpowered relative to the signal Amplitude it being asked to generate. Power starvation from a slow power supply is a frequent cause of underpowering.
A clipped waveform is one in which the gently rounded peaks and valleys of the AC audio wave are instead sliced off or clipped, to yield what looks a lot like a square or alternating DC wave. When DC is applied to a speaker, the voice coil has no means of propelling itself relative to a constant magnetic field. Instead, it can only convert the incoming current to heat, and ultimately burns up. The effect of alternating DC on speakers is remarkable, irritating, painful, and short. If you are able to hear evident Distortion at high volume levels, or smell smoke, reduce the volume. It may already be too late for your speakers, but at least you may be able to save the amplifier."

Maxima Dan

So how does this apply to your original post on clipping?

Luquire

"Also the hever charging and never discharging that was talked about is called cliping. the capacitor is considered a voltage source that comes on when there is a drop in the voltage (i.e. AC power). With AC power it keep the power much more linear. It sort of straightens out the Sinusoidal wave.(sort of) This clipping could happen when your system hits really hard or something that causing a dip in the voltage. The the capacitor has a draw on it which makes it release some of its stored energy (e.g. battery) at a certain rate which helps to slow the sudden drop in current until the battery and alternator can recover."

friendhasmax

i know what clipping is, and it has nothing at all to do with ur post about clipping lol. stop reading definitions that you clearly do not understand. better yet, just stay the he!! off the forum.

Maxima Dan

I have never heard of a cap charging and discharging as "clipping". Are you implying that the cap is helping to keep the input voltage to the amp constant and therefore preventing it from trying to exceed its' rail voltage?

friendhasmax

Maxima Dan you are talking to a brick wall here lol.

AscendantMax

iTrader: (7)

Slow Moe

iTrader: (2)

This thread has been very informative, I think?

friendhasmax

id say it was more entertaining

Luquire

I dont understand why there is such hostility from you. How old are you. You think by putting me down you are going to look tought or something. my intention was never to highjack this thread but your pompous A$$ just wont shut up. Oh by the way where were you educated at. I was just wondering so i would knock i off of the list of graduate schools i am wanting to attend.

AscendantMax

iTrader: (7)

ehh, he doesn't mean anything bad. maybe his choice of words was a bit harsh, but all he wanted to do is get the facts out.

friendhasmax

im just tired of reading posts from people that do nothing but put up off the wall information..people get confused enough as it is. when people start reading posts like yours and the other guy who thinks caps are batteries, they get even more confused. unless you are an EE, then just let me do the explaining. i didn't mean anything by it, but there is just so much wrong information out there from people who really don't understand the topic. i appologize if i came accross as vindictive.

Luquire

I am an EE. Thats why it seemed vindictive

friendhasmax

you are an EE? i find that hard to believe because an EE would never ask something like this. you can't put DC into a speaker unless you wanted to destroy the speaker. also, 2 or 4 ohms is not the correct resistance to discharge a capacitor through. you should already know this if you are an EE. even a first year EE student knows this, or even a kid taking high school physics knows this.

Luquire

Actually i am an Electrical and Computer Engineer and i dont realy think that discharging that capacitor by hooking it up to a speaker is very bad. You can hook up capacitor in line with a speaker in order to filter certain frequencies. That is called a filter. (butterworth may ring a bell). Plus a lot of speaker installers place a DC voltage directly to a speaker to see which direction the speaker moves.(out is positive in is negative) If this can be done on a speaker then surely a Cap can be hooked up to it. how many times have u done a speaker installation. Geez you sound so arrogant but you have not given any strong proof to back up you information.

friendhasmax

it's a filter when an AC waveform is applied to the speaker, in DC cases a cap is not a filter. a 9volt battery doesnt supply the same amount of current to a voice coil that a discharging cap would. discharging a cap into a speaker would destroy it, go ahead and try it and see what happens. and i have done countless installations.

D Love

Your equation is wrong.

friendhasmax

he copied it from a website...he doesn't even know what the function represents or where it came from

D Love

LOL, well they're wrong too then... Unless their tau is different from what all other EE's use.

Maxima Dan

No, that equation is way off. Tau is still the time constant and is still = RC. I pretty much glanced over it and decided to let it go the first time since it really didn't pertain to anything in this thread. Can't believe that this thread was resurected, though.

friendhasmax

haha my abd, i didnt take a look at the equation...yea its way off...my bad fellas..shoulda caught that a long time ago lol.