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PostPosted: October 13th, 2015, 9:57 pm 
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You should compare a capacitor to a compressed air cylinder not a water tank. WIth a capacitor as you increase the voltage (pressure) you add more charge(cubic feet of air) to the capacitor. Water is not compressible. With hydraulics you can transfer energy but cannot store it. WIth pneumatics you can both transfer and store energy. The stored energy in a compressed air cylinder is dependent on both the pressure and voume of air inside. WIth a capacitor the stored energy is dependent on the voltage and quantity of charge.

Tom


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PostPosted: October 13th, 2015, 10:06 pm 
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Actually, a water surge tank is the perfect analogy. All those of us who have well water use these 24/7. It's simply a sealed water tank that's fed from the bottom. Initially, it's full only of air, as more water is fed in from the bottom, the air is compressed, and the water pressure increases. In use, it works exactly like a capacitor, smoothing the surges of the water pump, and providing a surge volume when there are demand peaks.

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PostPosted: October 13th, 2015, 10:37 pm 
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As those of you who have wells know the surge tank only works when there is air at the top. I remember having to drain the tank and add air when the air got dissolved in the water. It is the air that stores the energy to allow the water to be sent through the pipes when the pump is not running. If the air gets absorbed, since the water cannot compress and store energy the pump cycles on and off continuously. To help prevent the air from disolvng in the water modern tanks have a diaphragm part way up the tank to separate the air from water.

Tom


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PostPosted: October 14th, 2015, 8:32 am 
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chris1973 wrote:
Stuart Polansky wrote:
I actually have a few books you can borrow. If you like, I'll bring them down to DC from York next weekend, and I can bring them over to your house next week. I need to hear those speakers!!!!

Stuart


Certainly!!

Thank You!!

I just made a new manipulation to the speakers I like! Small adjustment to the sand in the stands. The last time I adjusted it was before there was marble on the bottom of them, and I thought it would be worth revisiting!

8505 Crowley pl. Alexandria VA 22308 (703) 780 7597

Give me a heads up which day. Thursday I'm busy, but I should be around the rest of the week! Mon, Tue, Wed, Fri.

Thanks again Stuart! I hope you like the speakers!

Chris


Looking forward to it, Chris!

Thinking Tuesday, but we can firm that up later!

Stuart


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PostPosted: October 14th, 2015, 10:45 am 
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OKAY guys -- let's get one thing clear. Capacitors do not pass a signal through them. You may now faint. :confusion-confused:

What happens is the capacitor in an audio circuit blocks D.C. and the audio signal circulates around the capacitor (plate to plate) -- not through it. :angry-banghead:

A signal or voltage can go through a capacitor when the dielectric fails and shorts out -- that's why working voltage ratings are so important. :character-oldtimer:

If you study any schematic where there is a coupling capacitor you will note a complete circuit around the cap with reference to ground.

With power supplies the capacitor is used for the purpose of storing a charge for release that helps smooth out the pulsating D.C. from the rectifiers and to offer some energy storage for circuit demands.

My two cents and I expect change. :crazy:

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PostPosted: October 14th, 2015, 11:09 am 
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I would be interested in such a meet!


tomp wrote:
David Berning and I have both offered to hold meetings where we delve into the electronics but got little positive response. If there are enough members that would like to do that let either of us know and we could put something together at probably two levels, beginning and advanced.

Tom


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PostPosted: October 14th, 2015, 11:14 am 
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SoundMods wrote:
OKAY guys -- let's get one thing clear. Capacitors do not pass a signal through them. You may now faint. :confusion-confused:


You're confusing signal flow with electron flow :angry-banghead: :angry-banghead: :angry-banghead:

Roscoe

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PostPosted: October 14th, 2015, 1:37 pm 
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Roscoe is correct. It may help to think of a capacitor as a room divided in half by a fence. To start with when there is no voltage (body pressure) difference across the capacitor because each half of the room has the same number of people in it. They are all happy and there is no pressure to leave the room. If another person enters one side of the room there is a pressure on the fence that pushes one person from the other side out of the room. If you were to look at the room from the outside you would only see one person entering on one side and another leaving on the other side and you would think the person walked right through the room. That is what happens in the circuit. However, the extra person in one side of the room has increased the body pressure (voltage) on that side in reference to the other side. If that continues with people coming in on one side and people leaving on the other, the pressure on one side will increase with respect to the other.

However, from the outside the flow(signal) through the room looks like they are going right through except for the increase in pressure on one side. If it continues, one of two things will happen. Either the body pressure inside one side of the room wil reach a point where no one has the strength to enter the room and there will be stability (DC blocking) or the fence will break (insulation breakdown) in which case people will continue to pass through the room as if were essentialy not there.

Assuming that people both enter and leave the same side of the room in quantities that do not build up body pressure high enough to break the fence, the people flow (signal) will pass through the room in both directions (AC coupling). Then you have to look at the size of the room to determine the pressure buildup vs the number of people moving. If the room is very large (high capacitance) a reasonable number of people going in and out will have little effect on the pressure (voltage) difference across the room. If the room is very small the pressure difference will build up quicker.

If you have a fixed number of people entering on one side of the smaller the room the quicker the pressure will build up. If the time between the change in people directions is short (high frequency) the pressure build up will be small and the room will not have much effect on the people flow. If the time between direction changes is long (low frequency) the pressure will build up higher and the room will offer higher resistance to new people entering the room. If the room is larger, the time where people can flow into the room with low effect will be longer yielding better results (better low frequency performance).

You can also have a situation where there is an initial flow of people into one side of the room that is not enough to break down the fence but then people enter and exit the room in equal numbers that are insufficient to break down the insulation when they enter the room on the side where there is already an excess of people. This is an example where an AC signal can pass through a capacitor that is blocking the steady state DC signal.

As far as energy storage, if a bunch of people are pushed into one side of the room the pressure will build up and they will try to reach the happy state where there is no body pressure on them in relation to the folks on the other side. If you stop pushing them in and give them a chance to exit they will use the body pressure to force themselves out and produce a people flow somewhere in the connecting corridors until they get to the original happy balanced state.

I hope that this is not a ridiculous analogy to you but makes sense.

Tom


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PostPosted: October 14th, 2015, 1:42 pm 
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Hey Roscoe!

Not at all. There is no electron flow through a capacitor only around it. Let's say you have a cathode follower with a capacitance coupled output.

The circuit created with the next component -- say the input of a power amp. -- is the load to ground (with the grid or base utilizing the signal for further amplification) back through the connected ground of the interconnect up to the cathode resistor and the coupling capacitor. The audio signal circulates around from plate-to-plate of the coupling capacitor. The dielectric of the capacitor is just that and nothing more -- a non-conductive element.

It is easy to think that you have "signal flow" but the reality is that it is a "back-and-forth" thing going on. Now looking at transistor theory -- you have what is known as a semi-conductor that fits your description. An entirely different animal. :ugeek:

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PostPosted: October 14th, 2015, 1:44 pm 
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Hey Tom!

What you just described is the hole theory for transistors. Just saying. :character-oldtimer:

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