[Nisbeth]

Let's consider this, slightly flawed, rectifier circuit with the connections for AC and DC mixed up. Assuming this was a completed, soldered PCB, would it be possible to get it to work correctly but simply flipping some of the diodes around? And if yes, which diodes would have to be flipped so that the polarity on C1 is correct?


/U.

PS: Now, this is of course a purely hypothetical situation, naturally I would never do anything as stupid as this in real life

 

[FallenAngel]

Looks like you just need to flip D1 and D3 and you'll have it working.

 

[Glowing-Tube]

Quote:

Originally Posted by Nisbeth /img/forum/go_quote.gif Let's consider this, slightly flawed, rectifier circuit with the connections for AC and DC mixed up. Assuming this was a completed, soldered PCB, would it be possible to get it to work correctly but simply flipping some of the diodes around? And if yes, which diodes would have to be flipped so that the polarity on C1 is correct? /U. PS: Now, this is of course a purely hypothetical situation, naturally I would never do anything as stupid as this in real life

Very funny question. Just flip D1 and D3 then it will work. Next time you draw a schematic renember to make the rectifier bridge connection right.

Med venlig hilsen/Best regards,

Torben

 

[Nisbeth]

Thanks both of you

/U.

 

[jsmithepa]

Ppl build discrete rectifiers still? I switched to one-chip rectifier long time ago.

 

[Roee2807]

Why put capacitors parralel to each diode?
isn't one cap parrallel to the load is enough ?

 

[Nisbeth]

jsmith: Most "audiophiles" will argue that discrete rectifiers can be made to perform better than a single-chip solution by using high-speed and/or soft-recovery diodes. I consider this nearly irrelevant for audio as these high-spec diodes are designed for much more demanding use but I still use discrete bridges in some projects - if you already have the diodes the only additional expense is a bit of board space (and the time spent troubleshooting it when it doesn't work of course

)


Roee: The caps across each diode are so-called snubber-caps which supposedly cancel out high-frequency noise generated when the diodes turn on and off. Again, this is probably not really necessary for audio but it is considered "good design practice" in many other applications and so I've included it. In applications where it really matters the exact value of the capacitor is calculated to cancel out a specific frequency (and a series resistor is normally added as well), but for these applications the caps used are typically 1-10nF.


/U.

 

[FallenAngel]

Quote:

Originally Posted by Roee2807 /img/forum/go_quote.gif Why put capacitors parralel to each diode? isn't one cap parrallel to the load is enough ?

They remove noise added by the bridge, up to about 100pF is a good value here and it mostly is used for regular diodes because Schottky diodes don't make almost any noise anyway.

 

[nikongod]

Quote:

Originally Posted by jsmithepa /img/forum/go_quote.gif Ppl build discrete rectifiers still? I switched to one-chip rectifier long time ago.

how much do hexfred one-chip rectifiers cost?

nuff said.

 

[jsmithepa]

Quote:

Originally Posted by nikongod /img/forum/go_quote.gif how much do hexfred one-chip rectifiers cost?

Here's a buck.59 1.4amp unit from Radio Shack.

Those of u who prefer ALL discrete, be sure yr soldering skill is perfect else bad solder joints may do away with your "improved" sonic discrete quality.

 

[nikongod]

Quote:

Originally Posted by jsmithepa /img/forum/go_quote.gif Here's a buck.59 1.4amp unit from Radio Shack. Those of u who prefer ALL discrete, be sure yr soldering skill is perfect else bad solder joints may do away with your "improved" sonic discrete quality.

it uses fast recovery, quiet switching diodes? all you have shown is that there are CHEAP parts available from rat-shack amongst other places.

regarding soldering skill: building a discrete rectifier takes 8 solder joints on a PCB. compared to 4 for a door-slammer diode system i'd take the risk....