How to calculate the value u farad of a dc capacitor?

[wkyong]

If a dc voltage generated by a bridge rectifier & dc capacitor is 250vdc & has to be loaded about 3A,what is the u farad of the dc capacitor needed?
How to calculate?
Thanks!!

 

[Mikebits]

Is the answer due tomorrow?

 

[Pommie]

I doubt it's a homework question as there isn't enough information to answer it.

What is the minimum voltage that whatever it is supplying will tolerate? Or, how much ripple is allowable?

Mike.

 

[Pommie]

A quick google turned up this page.

Mike.

 

[Centretek]

Depends on the ripple suppression required.The smoother the O/P the larger the capacitor.
HINT: The capacitor has to supply the 3 amps for the time between DC pulses.

 

[rjvh]

Just have a look in the search of this forum as the same question whas answered about 3 a 4 months ago

Robert-Jan

 

[bananasiong]

I copied this from Hero.

 

[sniper007]

what mean F in equation ?

 

[audioguru]

F is the frequency coming from the rectifier bridge. It is double the mains frequency so it is 100Hz or 120Hz.

 

[dknguyen]

If a dc voltage generated by a bridge rectifier & dc capacitor is 250vdc & has to be loaded about 3A,what is the u farad of the dc capacitor needed?
How to calculate?
Thanks!!

THere is iterative math involved...but I forget it all.

 

[picbits]

The answer is simple.

The biggest capacitor you can find in your junk box

If it hums then stick a few more in parallel until it stops humming

 

[erosennin]

The answer is simple.

The biggest capacitor you can find in your junk box

If it hums then stick a few more in parallel until it stops humming

Definitely, I agree with this 100%, ahaha... By this theory though, the 71000uF Caps I scavenged from a TV are starting to run out...

 

[Thunderchild]

I was given the formula for a full wave bridge rectifier of 20'000/(V/I) but as that was in a crappy Italian school where I knew more than some of the teachers so I'd not stake my life on it !

 

[Thunderchild]

The answer is simple.

The biggest capacitor you can find in your junk box

If it hums then stick a few more in parallel until it stops humming

thats a very good rule of thumb and rather puts it all in nutshell