A full-wave rectified signal of 18 Vp is connected to a 400 uF filter capacitor. What is the ripple voltage.

Is there something wrong with the problem or is it just my understanding. I know the formula, which is ripple votlage = 2.4(Idc)/C.
But based on the problem why is there a missing parameter the Idc. Can someone explain this to me? Thank you

 

The current drawn by the load will have an effect on the ripple voltage. Where did you get the formula with a factor of 2.4, and are you looking at Peak to Peak or RMS ripple voltage?

 

What formula am I going to use here based on the problem?

 

Simplified formula for Vr(rms) = Idc/4sqrt(3[f][C])

 

what is the formula for ripple voltage after the capacitor filter?

 

Hello,

Read the attached PDF from page 31 and on.

Bertus

 

How can I Find the current "I"?

 

Hello,

The ripple is dependend on the drawn current, wich is dependend on the used load.
Did you see page 34 of the attached PDF for the effect of the load on the ripple?

Bertus

 

Simplified formula for Vr(rms) = Idc/4sqrt(3[f][C])

That formula makes no sense. You are taking the square root of (frequency * capacitance). That will not result in anything that, when combined with a current, gives you a voltage.

Where did this formula come from? The sqrt(3) normally appears in equations dealing with three phase systems.

You seem to only be concerned about someone feeding you a magic formula and not on understanding what ripple voltage is or how to determine it (beyond plugging numbers into a magic formula that you don't understand).

 

A full-wave rectified signal of 18 Vp is connected to a 400 uF filter capacitor. What is the ripple voltage.

Is there something wrong with the problem or is it just my understanding. I know the formula, which is ripple votlage = 2.4(Idc)/C.
But based on the problem why is there a missing parameter the Idc. Can someone explain this to me? Thank you

Hello there,

For this problem, the ripple voltage can be in peak units or peak to peak units, it does not matter. That's because there is a simplification when there is no load.

Any kind of approximate formula will have the load current included in the 'formula', but if the load current is zero then we get perfect filtering so then what is the ripple voltage?

There are exact ways to handle this calculation and approximate ways to handle it, but either way will come out with the same result (condition cap ESR=0) for this particular problem, so almost any approximate formula will work as long as it is not too bad
It would be good to look for a better formula too however.