ROBERT SAYRE wrote in a message to ROY J. TELLASON:

JB>     What's this one called?
JB>     _______________________ +
JB>        |               |
JB>        |               |
JB>      |/'               |
JB>    --|~              -----
JB>      |\              ~~T~~
JB>        |     output    |
JB>        |-----o    o----|
JB>        |               |
JB>      |/'               |
JB>    --|               -----
JB>      |\,             ~~T~~
JB>       ~|               |
JB>        |               |
JB>    ~~~~~~~~~~~~~~~~~~~~~~~~ -

RS>  A waste of a capacitor? 

RJT>  I've often wondered about that.  Amps with split supplies like
RJT> that which have two capactors in series like that are effectively
RJT> getting half the capacitance value,  with them in series like that.
RJT> Why not use one big ca across the whole thing?

RS>  Actually, there should be one proper value of capacitor (based on 
RS> the rest of the PS design) that is most effective for removing 60 
RS> Hz, which is what the "filtering" is all about. It may not
be "the 
RS> largest capacitor you can find".

How would you figure it?  The "rest of the p.s" in most cases
would consist of the transformer winding and rectifier diodes,  nothing
particularly special there...

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