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P

Paul Taylor

Jan 1, 1970
0
Phil Allison said:
"Paul Taylor"


** That is the way everyone usually does it.

Except when they want to use positive reg ICs like the LM338K for both
rails.



..... Phil

Phil would this still work fine even if i was drawing 4.5A from the positive
rail and only 0.5A from the negative?

Cheers Paul
 
P

Phil Allison

Jan 1, 1970
0
"Paul Taylor"
Phil would this still work fine even if i was drawing 4.5A from the
positive rail and only 0.5A from the negative?


** Yes.



...... Phil
 
R

Robert Baer

Jan 1, 1970
0
Paul said:
Hi i was looking for a bit of advice! I have built a dual +/-15v power
supply running from a 18v 225VA torodal on 2 separate windings, I am pulling
4.5A on the positive side and approx 0.5A on the negative side, the positive
rectifier is cooking i tried replacing this with an 8A one and it still does
it has anybody else come a crossed this and know what the problem is, i have
checked that the windings are in phase and wired correctly i can post a full
schematic on request.

Thanks Paul
Tell your cooking rectifier that i like my hot dogs well done.
 
J

Jamie

Jan 1, 1970
0
Paul said:
Hi i was looking for a bit of advice! I have built a dual +/-15v power
supply running from a 18v 225VA torodal on 2 separate windings, I am pulling
4.5A on the positive side and approx 0.5A on the negative side, the positive
rectifier is cooking i tried replacing this with an 8A one and it still does
it has anybody else come a crossed this and know what the problem is, i have
checked that the windings are in phase and wired correctly i can post a full
schematic on request.

Thanks Paul
Yeah, you're overloading it?, or you need a heat sink for it.
Also, beware when selecting rectifiers, it may be in your best
interest to select one with a voltage rating just above what you'll
be inputting to it.
 
E

Eeyore

Jan 1, 1970
0
Jamie said:
Yeah, you're overloading it?, or you need a heat sink for it.
Also, beware when selecting rectifiers, it may be in your best
interest to select one with a voltage rating just above what you'll
be inputting to it.

More than 'just' above actually.

Graham
 

neon

Oct 21, 2006
1,325
Joined
Oct 21, 2006
Messages
1,325
acording to you you are trying to dissipate 4-5 watts well that is cooking allright it has nothing to do with balacing ground if it has +/-15v you just got to remove 5w of heat somehow heatsink/airflow will do it otherwise whatch it cook there are no other methods to cure the problems. heat comes as radiation,conduction,conventional.
 
C

colin

Jan 1, 1970
0
Paul Taylor said:
Hi i was looking for a bit of advice! I have built a dual +/-15v power
supply running from a 18v 225VA torodal on 2 separate windings, I am
pulling 4.5A on the positive side and approx 0.5A on the negative side,
the positive rectifier is cooking i tried replacing this with an 8A one
and it still does it has anybody else come a crossed this and know what
the problem is, i have checked that the windings are in phase and wired
correctly i can post a full schematic on request.

Thanks Paul

it will dissipate about the same amount of heat,
that heat needs to go somewhere
too hot to touch doesnt mean its too hot,
if it realy burns you the instant you touch it that probably means it is too
hot.

ive tried using synchronous mosfet rectification and it can be quite
effective at reducing dissipation,
but its perhaps a tad overcomplicated unless you realy need it.

Colin =^.^=
 
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