Center tapped transformer rectifier question

[Radio Fox]

Re: Center tapped transformer rectifier question

Keep it simple?

Your diagram shows 2 diodes in series directly across the outer winding of the transformer.

Something's gonna blow!

[Dannyx]

Re: Center tapped transformer rectifier question

What do you think of the one I posted then ? Would that work ? It's like starting off by rectifying just one of the windings (with respect to the center tap) and then adding an additional bridge for the other one too so in theory nothing should go boom.

[budm]

Re: Center tapped transformer rectifier question

Your diagram shows 2 diodes in series directly across the outer winding of the transformer.

Something's gonna blow!

Two more diodes are also connected across the center tap and the top and bottom windings.

[eccerr0r]

Re: Center tapped transformer rectifier question

Go with mariushm's solution if you want a common 0V point.

None of the other ones will work trying to have a common ground point, at best. The halfwave version will work with a common ground point but has awful PF, awful regulation, and will require double sized transformer; and the double bridge solution requires that you keep the two circuits isolated from each other - they must never touch.

[Dannyx]

Re: Center tapped transformer rectifier question

The double bridge solution requires that you keep the two circuits isolated from each other - they must never touch.

They don't: one runs the supply, the other runs the fan - I'd say that's pretty separate

[goontron]

Re: Center tapped transformer rectifier question

Your diagram shows 2 diodes in series directly across the outer winding of the transformer.

Something's gonna blow!

Oh shit.... I need to pay attention better when designing schematics...

[eccerr0r]

Re: Center tapped transformer rectifier question

They don't: one runs the supply, the other runs the fan - I'd say that's pretty separate

As long as someone doesn't go and think "oh, this GND is black. That GND is black. It'll be just fine if I hook them up together..."

[Dannyx]

Re: Center tapped transformer rectifier question

As long as someone doesn't go and think "oh, this GND is black. That GND is black. It'll be just fine if I hook them up together..."

Nobody will tinker with the insides of this power supply and I'll label them Fan GND and supply GND

[Radio Fox]

Re: Center tapped transformer rectifier question

What do you think of the one I posted then ? Would that work ? It's like starting off by rectifying just one of the windings (with respect to the center tap) and then adding an additional bridge for the other one too so in theory nothing should go boom.

There's no need for a bridge for both supplies. You can full wave rectify both outputs with just 4 diodes, and still have a common earth. The attached diagram is similar to the one mariushm posted, except my one has the smothing cap -ve for the higher voltage connected to earth rather than the half-voltage output. (either configuration will work).

The 48Vdc output uses the 4 diodes as a bridge. The 23Vdc output uses D3 & D4 with reference to the centre tap to full wave rectify the output.

D3 & D4 will therefore be passing the combined current taken from both supplies, so will need to be rated accordingly.

[Dannyx]

Re: Center tapped transformer rectifier question

There's no need for a bridge for both supplies. You can full wave rectify both outputs with just 4 diodes, and still have a common earth. The attached diagram is similar to the one mariushm posted, except my one has the smothing cap -ve for the higher voltage connected to earth rather than the half-voltage output. (either configuration will work).

The 48Vdc output uses the 4 diodes as a bridge. The 23Vdc output uses D3 & D4 with reference to the centre tap to full wave rectify the output.

D3 & D4 will therefore be passing the combined current taken from both supplies, so will need to be rated accordingly.

In my case D3 and D4 are built into the bridge rectifier itself, though it's a 50a bridge, so I doubt it will complain.