Quote:
Originally Posted by aamefford /img/forum/go_quote.gif
Tomb and Majkel,
I'm sort of getting it here - the buffer acts like those buffer tanks in the compressed air line - I get that, though I always thought capacitors worked that way, storing up charge (current) to deliver upon need? Also, the buffer opamp doesn't really store current for later, but provides it via V=IR, with a voltage supplied to it, and a reduction in R from input to output, that results in increased I? And this voltage is supplied by the voltage gain amp? or the voltage rails themselves?
Thank you for all of your help so far, and continuing!
aamefford
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Well, you have a point. I guess that part of my analogy was in error.
To truly draw the analogy to an amplifier buffer, I suppose we need to consider an active device that insures flow from its own power source.
Trouble is, I'm not sure I know the device that regal is talking about. Most active, inline mechanical systems are used to boost pressure, not flow. If there is something that introduces additional volume, it's more than likely simply considered a paralleled source.
There might be something analogous in a primary/secondary pumping systems. However, it will take some considered thought to draw the analogy properly. I always have a problem with the industry standard terms in this case, because "primary" is not really the heart of the system - the "secondary" part of the system is the real guts, so to speak.
Casting that issue aside for the time being, though, what you really have is a de-coupled pumping system. The secondary is typically tuned to a specific head (voltage) to meet the load, and then the flow (current) is varied by means of a variable speed drive. These systems can get really large and sometimes the flow variance is done by staging multiples of pumps on and off.
To complete the analogy though, temperature is introduced as another variable, probably analogous to gain of the signal. After all, we aren't really simply flowing water (electricity) with amplifiers. Instead, we're flowing water that's had something special done to it (an amplified music signal).
So if we have a bunch of chillers in a decoupled, primary piping loop, they are applying gain to the water in terms of amplifying the temperature differential (actually negative gain in this case). The decoupled secondary pumping system then sits at a common head (voltage) determined by matching to the resistance of the load. The flow varies in response to cooling coils with control valves that increase or decrease flow to meet local temperature variances (amplifier volume control?). So the secondary pumps may in fact act as a system buffer, adjusting only flow (current), while the first stage primary system is applying negative gain in temperature to the energy of the water.
EDIT: Stated another way, the chillers in the primary loop apply gain to the "signal" (refrigerated water). However, the flow goes nowhere unless the secondary system is used to distribute the current of the amplified water to the load. END EDIT
Probably it would be easier to think in terms of hot water systems, since the temperature differential is a positive gain, but the principles are the same. The difference is that the gain is so high in hot water systems that very little flow is needed and the systems are typically less complicated. Primary/secondary systems with variable flow are not as common. Steam is similar, but has its own peculiar problems. Maybe heat systems with their high differentials are analogous to a simple CMoy with high enough voltage being able to reasonably power a high impedance headphone.
Probably a lot of holes in those analogies, too, but I gave it a shot.
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