oh by the way, my transformer says 230VAC/50Hz, but my mains here is 230VAC/60Hz, what will be the effect?
sometimes our main doesnt even reach 230V, many time its lower, 216V

 

Theoretically, you can draw 4A from a single 28V winding, but it may get hot.

Use both coils to get your rectified DC like below. Now each coil is only active half the time, so it is equivalent to putting the could in parallel.

View attachment 267701

is this same with this?

 

No, that gives separate + and - supplies.

Why do you want to use 4 diodes when 2 is sufficient and gives you 1/2 the heat?

Bob

 

oh by the way, my transformer says 230VAC/50Hz, but my mains here is 230VAC/60Hz, what will be the effect?
sometimes our main doesnt even reach 230V, many time its lower, 216V

Nothing much should change. The transformer will run slightly cooler with no load as the peak flux will be lower.

 

bob and lan, thanks for the clarifications

 

oh by the way, my transformer says 230VAC/50Hz, but my mains here is 230VAC/60Hz, what will be the effect?
sometimes our main doesnt even reach 230V, many time its lower, 216V

And you may be able to get a little more power out as the higher frequency is often a bit better core efficiency wise.

 

Try this. Just leave the "-" connection of the bridge rectifier unconnected.

 

View attachment 267789
Try this. Just leave the "-" connection of the bridge rectifier unconnected.

is this tested?

 

Yes, it works. Most people just use two diodes, especially when you can get a dual common-cathode Schottky diode.

 

Yes, it works. Most people just use two diodes, especially when you can get a dual common-cathode Schottky diode.

are you talking about this?

 

are you talking about this?

Yes. For a 50V supply, it needs to be rated at 100V.

 

i dont even know i cant use a dual diode like that as a bridge rectifier, thanks mate, anyway can i use even if its not a common cathode?

 

i dont even know i cant use a dual diode like that as a bridge rectifier, thanks mate, anyway can i use even if its not a common cathode?

You could use it if it were common anode, (you would get a negative output) but not if it has two diodes in series.

 

is using this dual schottky better than 2 normal diodes?

 

hi , i recovered the mainboard of the speaker amplifier, and it has a bridge rectifier marking is fagor gbu8k. any hint on secondary current now?

 

Here is the sheet on the rectifier.
https://www.onsemi.com/pdf/datasheet/gbu8b-d.pdf for rating