Bipolar PSU diode bridge question

[Alexandr.L]

Hello!

I starting to build PSU and found some old schematic what i draw under control of my old friend who know a lot more in schematic's than i =)
He recommend use two bridge rectifiers for better stability and quality (unfortunately in my country power quality is really low).
But at the moment i can't rememder does orientation of bridge rectifiers is correct.
Can some body help me with that moment, please?

Internal diode schematic of rectifier VD1,VD2 showing in left side of schematic.

Thanks in advance! And sorry for that stupid question, i'm very beginner in electronic's

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[EdisonRex]

The diode diagram is tipped on its side, if you're used to seeing bridge rectifiers. 2 and 4 are connected to the AC input, 1 and 3 give the DC output. The orientation of the diodes in the bridge are consistent however for AC input at points 2 and 4.

Usually we see those drawn 90 degrees rotated rightwards and the connections top and bottom are the AC input, left and right are the DC output.

If you look at the bridge as two parallel sets of chained diodes, the AC input is in the middle of the chain and the DC output is each end of the paralleled chain.

Note that you can use the bridge rectifier for either bipolar or single voltage output, it depends on whether or not you have a centre tap transformer.

Hope this helps.

[diablojoy]

Alexandr
your rectifier orientation as drawn looks good to me .

oh and welcome

[Osal]

Hello Alexandr,

There are two points here.

1)The schematics show that you are using RS1007 bridge rectifiers. Consult the data-sheet to see if pin configuration is right. Actually AC inputs are the inner pins that should be pins 2 and 3, I think.

2) The schematics, like they are now, are incorrect. Actually you are shorting the secondaries. Put it in a breadboard (with the convenient fuse!) you will see that it blows.

I recommend my PS2 http://electronic-sea.net/ps2.html , it is the best DIY power supply .
Thanks the LDO's, you can operate the power supply with a lower voltage transformer. Also, MIC2941 junction to case resistance is lower than the LM317. So the power dissipation is much more easy, this allows to use smaller heat-sinks and/or allow the regulator work at lower junction temperature, thus increasing its reliability. In my site you will see the schematics and the PCB's layout to etch it your-self.

[Alexandr.L]

Looks like I figured with all the questions on the scheme
All thanks guys

[diablojoy]

Osal is correct
from the data sheet the inner 2 pins- pins 2 and 3 are the AC inputs.
pins 1 and 4 are the output DC + and minus respectively
but they should be marked on the case as such in any case
your drawing is correct in so far as the diode orientations in the rectifiers are concerned but your pin numbering of the rectifiers is wrong

[Osal]

[diablojoy]

on alexander1's internal diode rectifier diagram left hand side
the diode orientations are correct as such for a rectifier but change the pin number 1 on his drawing to be marked as pin 2
and the pin marked as 2 to be marked as pin 1
so pin 2 would be on left hand side
pin 3 would be on the right hand side
pin 1 would be at the top
pin 4 would be at the bottom of that small drawing
yes ?

[Alexandr.L]

Pin numbers on left side diagram is just for showing what "that" VD1, VD2 symbols have inside him, cause i make him as single symbol, and not like separate diodes.
Pin destignation of complete symbol on schematic is:
top pin - 2 pin
bottom pin - 3 pin
left pin - - pin
rigth - + pin

Sorry if i brought you into confusion!