H
Hawker
- Jan 1, 1970
- 0
I have been using a formula to compute RMS voltage for full wave
rectified and filtered power for eons. I don't know where it came from,
or if it is even accurate, but the numbers I get are usually in the ball
park.
It seems to work great if the input capacitor is sufficiently large that
the ripple voltage is small. But if you make the capacitor to small the
numbers are negative, and hence not valid. Even if you have no capacitor
there is an RMS DC voltage. I googled and googled and could not find a
better formula. Does anyone have one?
What I am using is.
F=Frequency (120hz in us)
C = capacitor value
V = Peek Voltage
R = Load Resistor
Ripple Voltage = (F^-1 / (2*SQRT(3)*V) ) / (RC)
VDC = (1-((2F)^-1 / (RC))) * V
This works great for large caps and/or light loads but is not accurate
for small caps or large loads (you get negative numbers)
Obviously I need a better formula. Can anyone help?
Thanx
Hawker
rectified and filtered power for eons. I don't know where it came from,
or if it is even accurate, but the numbers I get are usually in the ball
park.
It seems to work great if the input capacitor is sufficiently large that
the ripple voltage is small. But if you make the capacitor to small the
numbers are negative, and hence not valid. Even if you have no capacitor
there is an RMS DC voltage. I googled and googled and could not find a
better formula. Does anyone have one?
What I am using is.
F=Frequency (120hz in us)
C = capacitor value
V = Peek Voltage
R = Load Resistor
Ripple Voltage = (F^-1 / (2*SQRT(3)*V) ) / (RC)
VDC = (1-((2F)^-1 / (RC))) * V
This works great for large caps and/or light loads but is not accurate
for small caps or large loads (you get negative numbers)
Obviously I need a better formula. Can anyone help?
Thanx
Hawker