Hello,
A simple question for you more experienced,


I'm talking about the 4 diode bridge rectifier and the way of using just 2
diodes, 1 on each side of the AC cycle.

I've seen both of the above types used in tube circuits.

Is there some way to define that the other of them is better for some
reasons?

How much trouble is that so called "diod switching noise" associated with
the bridge rectifier?


-at

"at" said:

I'm talking about the 4 diode bridge rectifier and the way of using just 2
diodes, 1 on each side of the AC cycle.
I've seen both of the above types used in tube circuits.
Is there some way to define that the other of them is better for some
reasons?

The bridge is used when there's no center tap (CT) on the tranny,
the two diodes are used if there is one.
Both are so-called full wave rectifiers.
The CT tranny will have e.g. 350V x 2, in total 700V.
The normal tranny will have just one 350 V winding.

So, the use of one over another is just a matter of what transformer
is in your possession.

How much trouble is that so called "diod switching noise" associated with
the bridge rectifier?

I usually add a "snubber" network over each diode, consisting of a
0.01 uF/1000V cap in series with 47 ohms/ 0.5 watts.

--
Sander deWaal
"SOA of a KT88? Sufficient."

"at"

I'm talking about the 4 diode bridge rectifier and the way of using just 2
diodes, 1 on each side of the AC cycle.

I've seen both of the above types used in tube circuits.

Is there some way to define that the other of them is better for some
reasons?


** It takes four diodes to make a bridge rectifier - the two diode
method is normally called "full wave" rectification.

Using a bridge rectifier is more efficient in terms of the transformer
size - since there is only one winding and it delivers current during both
half cycles of the AC supply.

OTOH, the full wave rectifier uses two windings of the same voltage as
the one needed for a bridge and each winding only delivers current on
alternate AC half cycles.




............ Phil

In article , "Phil Allison"
wrote:

"at"

I'm talking about the 4 diode bridge rectifier and the way of using just 2
diodes, 1 on each side of the AC cycle.

I've seen both of the above types used in tube circuits.

Is there some way to define that the other of them is better for some
reasons?


** It takes four diodes to make a bridge rectifier - the two diode
method is normally called "full wave" rectification.

Using a bridge rectifier is more efficient in terms of the transformer
size - since there is only one winding and it delivers current during both
half cycles of the AC supply.

Not only that, but the PIV across the diodes in the bridge is less than
that across the diodes in the "full wave" circuit. Also the bridge
circuit tends to be somewhat self protecting from power line spikes that
can zap the rectifiers in the "full wave" circuit as a result of the
leakage inductance between the two halves of the primary. This may not be
as important with today's diodes as it once was, but it can't hurt.


Regards,

John Byrns


Surf my web pages at, http://users.rcn.com/jbyrns/

Thank you for your good clarification of the differences.

-at

"at" wrote in message
...
Hello,
A simple question for you more experienced,


I'm talking about the 4 diode bridge rectifier and the way of using just 2
diodes, 1 on each side of the AC cycle.

I've seen both of the above types used in tube circuits.

Is there some way to define that the other of them is better for some
reasons?

How much trouble is that so called "diod switching noise" associated with
the bridge rectifier?


-at