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In Reply to: RE: You will be better off using those chokes as a plate load in a parafeed amp posted by Chip647 on November 30, 2016 at 16:16:32
What makes it terrible?
How about?
225v @70mA power transformer => Full wave bridge with Schottkys => 16H 12ohm LC choke => 50uf => 16H 12 ohm choke => 100uf => 105+v??
Follow Ups:
The problem is that "more" is not better. Once you reach a point when you have enough inductance in the power supply to achieve your filtering goals, simply increasing values does not make the power supply "more better".
You are setting up multiple resonance circuits (see formula above). With 16H and 2uf, you have a resonance frequency of 28hZ which is in the audio band.
Hey,
the ripple reduction is a function of L X C so if you double the L you can 1/2 the C and end up back where you started.
As for resonant frequency, that is simply a function of the ripple reduction required by the filter section and for any given amount of ripple reduction, the resonant frequency is constant. The only way to change the resonant frequency is to increase or decrease the filtering of a section.
While your example of a filter of 28hz being n the audio band is correct, the OP proposed 2m (which is 2000µ) of filtering which puts the resonant frequency under 1hz.
dave
"With 16H and 2uf, you have a resonance frequency of 28hZ which is in the audio band."
Look again. That's not 2uf, it's 2000uf.
PSUD2 uses "uf" for microfarad and "mf" for millifarad.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Couldn't make that out. Worse.
What about this one?
Put C1 as 0.2uf
Put C2 as 50uF
Put C3 as 100uF
You will have to change the transformer voltage to around 250 for the same output voltage.
Compare the current step response and the ripple voltage
The DCR of the chokes is so low that the filter will ring like heck unless the caps are made large.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
Edits: 12/01/16
Trouble with just trying to use parts on hand.
Hello Tre'!
Can I use 600v rating for the C1 (20uf) and 200v rating cap for both C2 (600uf) as well as C3 (1800uf)??
Thanks!
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