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Re: Accaptable ripple voltage

1/28/2005 8:27 AM
anonymous	Re: Accaptable ripple voltage Power supply ripple voltage falls under the 10% rule so often used in electronics. So, if the ripple voltage is 10% or less than the maximum power supply dc value, you’re ok. An easy calculation for Vr: Vr = Idc/fC In this case, Idc = 25mA (your number) F = 120 hz (Full Wave rectifier assumed , 60 if it’s a half wave) C = 10 uFd Then Vr = 20.83 volts (20.83/265) x 100% = 7.86% (I assumed the 265V after quick scan of the Firefly PSU) So, 10uFd caps will work fine. You might like a bigger one for the first stage – your call. 47uFd seems like overkill.

1/28/2005 8:27 AM

anonymous

Re: Accaptable ripple voltage

Power supply ripple voltage falls under the 10% rule so often used in electronics.
So, if the ripple voltage is 10% or less than the maximum power supply dc value, you’re ok.
An easy calculation for Vr:

Vr = Idc/fC

In this case,
Idc = 25mA (your number)
F = 120 hz (Full Wave rectifier assumed , 60 if it’s a half wave)
C = 10 uFd

Then Vr = 20.83 volts

(20.83/265) x 100% = 7.86% (I assumed the 265V after quick scan of the Firefly PSU)

So, 10uFd caps will work fine.
You might like a bigger one for the first stage – your call.
47uFd seems like overkill.

Replies:

anon My ears can easily hear 10% ripple.... -- 1/28/2005 9:43 AM