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

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wkyong

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

Robert-Jan
 
F is the frequency coming from the rectifier bridge. It is double the mains frequency so it is 100Hz or 120Hz.
 
wkyong said:
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!!
Click to expand...


THere is iterative math involved...but I forget it all.
 
Last edited:
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
 
picbits said:
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
Click to expand...

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