The real question is: how do I charge the stupid cap up? I'm following the instructions included. It has a little card that gets screwed down onto the top terminals. You connect the red wire to a 12v power supply and the black wire to ground. A green LED is supposed to light up. It turns off when the cap is fully charged. The LED doesn't light up. What the heck am I doing wrong? I'm attaching the wires to the appropriate connections on the amp. Should I hook the power up before the amp? Any help is greatly appreciated.
Car audio question: how do I install a stiffening capacitor?
- Thread starter Spoooon
- Start date
- Oct 30, 1999
- 11,815
- 104
- 106
Wait a minute... You're hooking up to the right wires on the amp?
You're hooking the wires up to the battery to charge the cap, right?
Whew!
Anyhoo... It would make more sense to me that the light would stay OFF during charging and then turn ON when it's charged. Just based on the way caps work.
Is the cap already charged? To find out, hook it up to the amp and energize the remote lead. Does the amp turn on for a few seconds even when not connected to the battery?
FYI: After the cap is charged is goes in-line on the + lead. I'm not assuming you're stupid, just want to make sure all bases are covered.
You're hooking the wires up to the battery to charge the cap, right?
Whew!
Anyhoo... It would make more sense to me that the light would stay OFF during charging and then turn ON when it's charged. Just based on the way caps work.
Is the cap already charged? To find out, hook it up to the amp and energize the remote lead. Does the amp turn on for a few seconds even when not connected to the battery?
FYI: After the cap is charged is goes in-line on the + lead. I'm not assuming you're stupid, just want to make sure all bases are covered.
i would have to make the same question johnnyguru did, it sounds like you're connecting the capacitor after the amp, and not to the battery, which is where it should go....?
See, right now I'm just trying to charge up the darned thing. Here are the instructions:
To charge your cap: place the charging card on the capacitor with the end marked "+" on the positive terminal of the cap. Hand tighten the supplied terminal screws to secure the charge card in place on both terminals. Connect the red wire to a 12v power source. Connect the black wire to ground. The green led on the charge card should light. When the green led goes out, your cap is charged.
I'm just trying to charge it up first. Though I did read that you don't have to slow charge your cap. From what I understood, I don't have to charge it up in the first place, I can just install it. Does that sound right?
btw: It's a 1 farad cap.
To charge your cap: place the charging card on the capacitor with the end marked "+" on the positive terminal of the cap. Hand tighten the supplied terminal screws to secure the charge card in place on both terminals. Connect the red wire to a 12v power source. Connect the black wire to ground. The green led on the charge card should light. When the green led goes out, your cap is charged.
I'm just trying to charge it up first. Though I did read that you don't have to slow charge your cap. From what I understood, I don't have to charge it up in the first place, I can just install it. Does that sound right?
btw: It's a 1 farad cap.
You could just hook it up without chargin it...but that wouldn't be too safe. It'll charge itself real quick that way. I dunno what that little card is but to charge a cap you connect a ground wire to the negative connect and ground it. Then you take the power wire from ur stereo that is hooked up to your battery and hook it up to a resistor. Then put the resistor to the positive terminal on the cap. It then should slowly charge. To make sure, take a voltmeter and test the cap. When it reaches 12 or so volts its done. Then connect the power wire from the amp to the positive side of the cap. So when your done you should have two wires coming from the positive terminal of the cap, the amp power wire adn the main power wire. Hope that helps.
you need to put a small resistor in series with the LED and the CAP. The capacitor is charging so fast that you can not see the light. I does come on, I guarantee, but for a very very short period of time.
the time for the cap to charge completely will be 5 * R * C.
If you have virtually no resistance, the cap will charge way to fast for you to see the light, as it were.
the time for the cap to charge completely will be 5 * R * C.
If you have virtually no resistance, the cap will charge way to fast for you to see the light, as it were.
Well, I went ahead and installed it. Everything is working fine so far. I have no idea if the cap is doing it's job. I figure, if the cap was bad, something wouldn't be working...true?
Did that once while screwing down the terminals once....scared the sh!t outta me.... As long as it has a 12 volt charge..it should be all good.
Excuse me, but I'm an electronic design engineer, and I've never heard of a stiffening capacitor. Who sells these things, and what are they supposed to do?
It sounds like you're just adding more storage to the output of the power supply. If there is noise on the supply, and if you add enough capacitance, you might reduce ripple on the supply, which might reduce noise in an audio device. If it's a power amp, it's going to have to be one hell of a large cap to make a difference. Basically, you need to know more about the problem before you attempt to solve it this way.
If the LED is supposed to turn off when the cap is charged, then if the supply has a relatively low output impedance the LED would not be on very long. In fact, the cap could charge so fast that you didn't even see it flash very briefly before it went out. The fact that there's an LED, at all, makes this sound like a goody packaged up to sell for more than the price of one big 12 volt cap, one resistor, and one LED (total parts cost would be under a couple of bucks).
It sounds like you're just adding more storage to the output of the power supply. If there is noise on the supply, and if you add enough capacitance, you might reduce ripple on the supply, which might reduce noise in an audio device. If it's a power amp, it's going to have to be one hell of a large cap to make a difference. Basically, you need to know more about the problem before you attempt to solve it this way.
If the LED is supposed to turn off when the cap is charged, then if the supply has a relatively low output impedance the LED would not be on very long. In fact, the cap could charge so fast that you didn't even see it flash very briefly before it went out. The fact that there's an LED, at all, makes this sound like a goody packaged up to sell for more than the price of one big 12 volt cap, one resistor, and one LED (total parts cost would be under a couple of bucks).
Harvey, a stiffening cap basically is a 1 Farad or bigger cap you install on the power leads of a amp to give it more kick. It keeps the voltage a little more constant. With some Class A or B amps, when they hit, current can't keep up and voltage tapers off. A stiff cap acts like a normal capacitor obiviously and fills in the demand for current.
They are well used in the car audio realm
They are well used in the car audio realm
Monel -- Thanks for the info. If that's what I wanted to do, I think I would try a couple of other solutions that might be cheaper and better.
Does anyone seriously try to run class A amps? That would be a huge current suck without much sonic improvement to show for it. You have to get to seriously clean audio environments to have a chance at hearing the difference between class A and class AB. Class B amps are another story, because you get crossover distortion. However, even with a pair push-pull balanced amp, your power is still limited by the 12 volt supply and the lowest impedance you can build into the speaker. 12 volts squared / 4 ohms will only give you about 18 watts RMS.
If you make super low impedance speakers, wire impedances get in the way, and your damping ration falls to sh8. It seems to me that a better solution for high power car audio amps would be switching amps. They can output much higher voltages, so you don't have to try to build speakers with ridiculously low impedances.
A better solution for the equivalent of a 1 F cap across 12 volts might be a smaller cap and a honking power transistor configured as a capacitance multiplier, or, better yet, a good active regulator circuit, but I'd have to calc it out. Unless there is some serious drop across the wires to the battery, I think a direct connection to a storage battery would swamp out any cap. If that's the problem, just use a heavier guage of wire. I could be wrong, but this cap idea sounds like more like hype than a solution.
Does anyone seriously try to run class A amps? That would be a huge current suck without much sonic improvement to show for it. You have to get to seriously clean audio environments to have a chance at hearing the difference between class A and class AB. Class B amps are another story, because you get crossover distortion. However, even with a pair push-pull balanced amp, your power is still limited by the 12 volt supply and the lowest impedance you can build into the speaker. 12 volts squared / 4 ohms will only give you about 18 watts RMS.
If you make super low impedance speakers, wire impedances get in the way, and your damping ration falls to sh8. It seems to me that a better solution for high power car audio amps would be switching amps. They can output much higher voltages, so you don't have to try to build speakers with ridiculously low impedances.
A better solution for the equivalent of a 1 F cap across 12 volts might be a smaller cap and a honking power transistor configured as a capacitance multiplier, or, better yet, a good active regulator circuit, but I'd have to calc it out. Unless there is some serious drop across the wires to the battery, I think a direct connection to a storage battery would swamp out any cap. If that's the problem, just use a heavier guage of wire. I could be wrong, but this cap idea sounds like more like hype than a solution.
Well, my amp is a class AB amp.
Harvey - You're right about a direct connection to a storage battery being better than a cap. However, my cap cost about 45 dollars whereas a good deep cycle battery for car audio use runs from 170 to 270 dollars.
Harvey - You're right about a direct connection to a storage battery being better than a cap. However, my cap cost about 45 dollars whereas a good deep cycle battery for car audio use runs from 170 to 270 dollars.
The capacitor should be hooked up close to the amp and yes it's doubtful that you'll see the LED comeon unless you play your music really loud and it drains the cap on loud bass peaks. In home amps the capacitors are inside the amp but they have more room then most car amps.
I have 4000 watts in my car.....boom !
PS: If your not sure whether the cap is working or not just give it a charge and find a cat.........MEOW !!!
I have 4000 watts in my car.....boom !
PS: If your not sure whether the cap is working or not just give it a charge and find a cat.........MEOW !!!
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