crc pi filter

tenderland · 2nd January 2007, 10:48 AM

When calculating the total capacitance for a crc filter. Do you simply
add each parallel capacitor, and do you split the values evenly

eg you want 1000uf use 2 500uf in the filter.

J

AndrewT · 2nd January 2007, 07:32 PM

Hi,
you got me confused.
A CRC does not have caps in parallel.
or
do you want to run caps in parallel to achieve each C value?

tenderland · 2nd January 2007, 09:02 PM

see attached

I am building a +/- 15 volt 300va supply for a ALEPH X

AndrewT · 3rd January 2007, 06:50 AM

Hi,
that CRCR filter shows 47pF which is an RF filter.

The caps are not in parallel, they are two cascaded filters.

If you replace the caps with 500uF the frequency of the filter will move down 7decades from 68MHz to 6Hz.

This will filter the mains hum significantly. Adding the second RC filter will further filter the mains hum.

500uF will support short term peak output currents of about 250mA but the output voltage will sag significantly due to the series 50r +100r even with only a 50mA load

2nd January 2007, 10:48 AM	#1
tenderland diyAudio Member Join Date: Jul 2004 Location: us	crc pi filter When calculating the total capacitance for a crc filter. Do you simply add each parallel capacitor, and do you split the values evenly eg you want 1000uf use 2 500uf in the filter. J __________________ "If every one is making wheels , why make wheels ? " Steve Jobs

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2nd January 2007, 07:32 PM	#2
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, you got me confused. A CRC does not have caps in parallel. or do you want to run caps in parallel to achieve each C value?

3rd January 2007, 06:50 AM	#4
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	Hi, that CRCR filter shows 47pF which is an RF filter. The caps are not in parallel, they are two cascaded filters. If you replace the caps with 500uF the frequency of the filter will move down 7decades from 68MHz to 6Hz. This will filter the mains hum significantly. Adding the second RC filter will further filter the mains hum. 500uF will support short term peak output currents of about 250mA but the output voltage will sag significantly due to the series 50r +100r even with only a 50mA load