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A capacitor has lower resistance (impedance) as frequency increases. Adding an emitter capacitor effectively lowers the emitter resistance as frequency increases. Since gain in a typical common emitter amplifier is collector resitance divided by emitter resistance, this decrease in emitter resistance will increase gain as frequency increases.

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Q: Why would there be a gain when you add the emitter capacitor to a circuit board?
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Why would the gain go up in a circuit board when you put an emitter capacitor in the circuit?

The emitter resistor is there to provide DC bias to the base. If it is not bypassed, then the AC output signal is also dropped across this resistor, effectively lowering the output swing. When a bypass capacitor is added, the DC bias still flows through the resistor, but the capacitor acts as a short circuit for the AC signal, so that the AC signal is not reduced. The capacitor selected must be large enough so it appears as a very low resistance at the lowest frequency the amplifier will pass.


What do you mean by emitter bypass capacitor?

a capacitor that bypasses a BJT's emitter bias resistor so the emitter is at AC ground but has a DC bias voltage on it to set operating conditions. without the bypass, the bias would not stay constant.


What happens when a start capacitor fails?

An open circuit, by definition, has no continuity, therefore there is no current flow. A failed capacitor in an open circuit would have absolutely no effect.


What happens when you remove capacitor in filter circuit?

The capacitors allow the signal to pass through, while 'blocking' the DC voltage level that the signal is 'riding' on. Are you asking to remove the capacitor and connect it straight through? If you had a multistage amplifier, then the DC riding voltage would try to get amplified as well, and the next stage amplifier would probably 'max out' and you'd wind up with just solid DC output, or components further along in the circuit could be damaged. If you're asking if the capacitor was taken out (like if it blew) then no signal would get through.


Why does the bypass capacitor decrease the input impedance in common emitter amplifier?

You would use a supply bypass capacitor in a common collector amplifier... It's necessary, to give the positive supply rail a direct AC connection to ground. Without it, I don't think the amplifier would work properly. However, if you're using a power supply and not a battery, then chances are that it HAS a big capacitor inside it, eliminating the need for any external capacitor.


If the capacitor store the charge from the magnetic field then the capacitor is called?

it wouldn't store a charge from the magnetic field, only the current induced on the circuit would be stored


How much is a circuit board kit?

Circuit board kits vary in cost depending on what type of circuit board you are building. You can buy circuit board kits from Amazon starting at $35.00. There are many other options out there as well.


How do you use a pcb as a capacitor in filter circuit?

A capacitor is simply two conductors in close proximity to each other, but not touching. This allows a charge to build up between them. It is entirely possible to build a small capacitor with a double sided printed circuit board. The area of the plates would be semi adjustable, in that you could cut out what you don't want. You can estimate the capacitance of a parallel plate capacitor with the equation... C = er e0 S / d ... where C is capacitance in farads, er is permittivity (also called dielectric constant), e0 is the electric constant, about 8.854 x 10-12 F m-1, S is area of overlap, and d is the distance between the plates. You would need to either know or measure the dielectric constant of the circuit board - for a vacuum, p is 1 - one way to measure is to build a test capacitor and measure its capacitance in a test circuit - perhaps an oscillator - and understand that (within limits) capacitance is proportional to the area of overlap and inversely proportional to the distance between the plates. For more information, please see the Related Link below.


How do you identify a printed circuit board mean of shape size number?

You would have to look inside your computer and take the circuit board out and examine it. It should have the information on it.


Regarding Capacitors- can any general capacitor work on a circuit diagram that shows a polarized capacitor or do you need a special capacitor for polarization?

A Polarized capacitor means that the capacitor is polarity sensitive. if you were to connect the capacitor incorrectly the capacitor would blow up. A capacitor that is marked as being polarity sensitive will have the negative lead labeled usually with a white strip. These capacitors can only be used in conjunction with a dc source. Always consult a professional when installing electrical equipment.


What is the main circuit that has many other components attached?

That would be the mother board.


What is the green thing call inside of electronics?

That would probably be the circuit board.