Some questions about reservoir capacitor

[hanhan]

Hi,
Please help me with these questions about reservoir capacitor. I used the source here: https://en.wikipedia.org/wiki/Reservoir_capacitor
The questions arose from my previous thread. I am trying to get some basic to understand better.
Thanks.

 

[Ratchit]

anhnha,

In the future, please do not ask more than one question in a paragraph when you designate it as one question.

Q1A. Read the following paragraph titled "Performance with significant impedance". The voltage across the capacitor will never follow the source voltage due to the diode being in series with source voltage and the capacitor.

Q1B. Of course not. There is a diode between the voltage source and the capacitor.

Q2A. What output of the rectifier are you talking about? Voltage or current? .

Q2B. No, the voltage across the diode and the voltage across the capacitor are two different values. Besides, the diode rectifies the current.

Ratch

 

[hanhan]

Thank you, Ratch.

In the future, please do not ask more than one question in a paragraph when you designate it as one question.

OK and sorry for that.

Q1A. Read the following paragraph titled "Performance with significant impedance".

I have searched the paragraph but I can't find it. Can you put the link here?

The voltage across the capacitor will never follow the source voltage due to the diode being in series with source voltage and the capacitor.

In this case let's assume that the diode is ideal. Thus, in the first quarter of the cycle, the voltage across the capacitor will be exactly equal to source voltage.
In the second quarter, when source voltage decreases, the diode turn OFF and the capacitor will discharge through the load.
Is that right?

Q1B. Of course not. There is a diode between the voltage source and the capacitor.

I forgot the diode!

Q2A. What output of the rectifier are you talking about? Voltage or current? .

I meant "voltage".
Assume that the diode is ideal, hence after 1/4 first cycle the capacitor has been charged to Vm ( the maximum voltage of sinosoidal input voltage).
Then in the second quarter, source voltage decreases and the diode diode turns OFF, capacitor will discharge through the load.
I was confused with the picture. I think they should not draw second quarter of a cycle as in the pictuce above because it plays no role in this case.

 

[Ratchit]

anhnha ,

I have searched the paragraph but I can't find it. Can you put the link here?

The link is the one you posted.

In this case let's assume that the diode is ideal. Thus, in the first quarter of the cycle, the voltage across the capacitor will be exactly equal to source voltage.
In the second quarter, when source voltage decreases, the diode turn OFF and the capacitor will discharge through the load.
Is that right?

Yes.

I was confused with the picture. I think they should not draw second quarter of a cycle as in the pictuce above because it plays no role in this case.

The diagram should have been labeled better. It is the voltage across the load, not the diode.

Ratch