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#1
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Coupling , Load and Bypass Capacitors
What are the differences between Coupling , Load and Bypass Capacitors
and what are their advantages. |
#2
Posted to rec.audio.tech
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Coupling , Load and Bypass Capacitors
On 10 Apr 2006 23:47:37 -0700, "Adnan" wrote:
What are the differences between Coupling , Load and Bypass Capacitors and what are their advantages. A coupling capacitor takes the signal from one part of a circuit to the next, while preventing and DC voltages from getting through. A load capacitor is generally a no-no in audio. It forces a device to deliver current, but without dissipating any power, thus resulting in no useful work being done. Generally you want a load to be a resistor, not a capacitor. A bypass capacitor is something which you use in a part of the circuit which has a vital DC function, but is not useful for the signal itself. A power supply would be such a device. The bypass capacitor is placed across the power supply and appears to the signal as a short circuit. The advantage of each is generally that if you need them, and you haven't got them, the circuit won't work. They are not some sort of alternatives from among which you can choose the best. d -- Pearce Consulting http://www.pearce.uk.com |
#3
Posted to rec.audio.tech
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Coupling , Load and Bypass Capacitors
Adnan wrote: What are the differences between Coupling , Load and Bypass Capacitors and what are their advantages. Not attempting to be snide, but that's like asking what the differencces are between tires, steering wheels and car and what are there advantages. Each serves a different function and each are required for that function. Further, the categories you list are so broad in their application that it's difficult to come up with some comprehensive definition that makes any sense. Take, for example, "bypass." You have bypass capacitors that do all sorts of tasks. For example, an emitter bypass capacitor is in combination with the emitter resistor to determine both the DC bias and the AC gain of a circuit. In a feedback loop, a bypass capacitor makes the high frequency gain of a circuit different than the low frequency gain. And, fr all intents and purposes, the large capacitors in the power supply can be considered bypass capacitors. You could even have a "bypass-coupling capacitor." You have a resistor coupling the output of one stage to the input of another. Put a capacitor in parallel with that resistor and, in combination with the load presented by the input stage, you have a different coupling at some frequencies than others. Indeed, you can make the argument that bypass capacitors are coupling capaciotrs are load capacitors. But whatever they're used for, the "advantage" is that the circuit design requires them, simple as that. |
#4
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Coupling , Load and Bypass Capacitors
mc wrote: A load capacitor -- well, load capacitance is usually something we try to get rid of, not something we add by adding a capacitor. A very important and not at all uncommon exception is that any transducer that is primarily capacitive, for example, a condenser microphone or a ceramic mic (for example, laboratory mics using barium titanate) MUST have a specific load capacitance to achieve their sensitivity specifications and frequency response. If the load is resistance, the result is a rising frequency response. If the load capacitance is not correct, the sensitivity will be off. Add more capacitance, say, with a longer cable and the result is NOT a change in frequency response but a change in broadband sensitivity. |
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