what would happen if.........?

[pointy]

if i connected 2x bridge rectifiers to the same transformer and then connected the 2 +out puts together.
would i then get humps above zero or only the same as with 1x bridge rectifier.

[DougL]

If I understand correctly, It would be the same.
However, since the devil is in the details, a schematic would change "I think" to "I know".

Doug

[pointy]

i was not certain that they would stay in phase

[Arnulf]

What is "in phase" with full wave rectification ?

Your first post omitted one key detail (the fact that both bridges are connected to the same ground), changing what would initially be "nothing much" into "depending on how well the diodes are matched" reply.

If diodes are matched well, current capacity will double. What is more likely though is that they will not be matched well, one set of diodes will conduct majority of the current and the other next to none (with these diodes not biased enough to conduct as much as the other set).

Why would you want to do something silly like that anyway ? If you need more current capaity, use beefier diodes.

[pointy]

if it worked out of phase there may be less need for a choke

[Sch3mat1c]

First of all, why?

What you propose will increase the current capacity by connecting diodes in parallel. The diodes will not share current evenly and will be prone to thermal runaway. A ballast resistor must be placed in series with each AC terminal (or alternately, each DC terminal, but not both, which would be redundant).

Tim

[pointy]

WHY?..................... it's sunday afternoon i was bored, and then i had this strange idea that it may stretch the top of the humps and overlap them down near zero.

"it was just some odd idea"

[DougL]

A+ for thinking out of the box.

Doug

[pointy]

don't you meant thinking while out of my box.............!

"iv'e not had much sleep lately"

[kevinkr]

Originally Posted by pointy

WHY?..................... it's sunday afternoon i was bored, and then i had this strange idea that it may stretch the top of the humps and overlap them down near zero.

"it was just some odd idea"

High Pointy, since the diodes are in parallel they are seeing the same ac phase and as a consequence there will be no difference between a single diode and two in parallel. The power available on that secondary is single phase.

Note that there are multi-phase rectifiers designed to run on 3 phase and in fact what you where thinking about is more or less the case there. So in a 3 phase system 100Hz full wave ripple becomes 300Hz ripple which is much easier to filter, and the period of each ripple component is a third of that found on single phase.

Unfortunately there is no convenient way to convert single phase ac to 3 phase ac as the phase relationships between each phase are 120 degrees in 3 phase as opposed to 180 degrees in single phase.. Usual methods include electronic or rotary converters.

Center tapped transformers running on single phase are still single phase with a phase relationship of 180 degrees between any two taps on the same winding.

Here is a site that explains 3 phase power as a point of interest: 3 Phase Transformers and Three Phase Power Transformer Models - The 3 Phase Power Resource Site