How do I double the voltage on diodes? Parallel or series?

series, posted on August 21, 2014 at 07:32:08
Tre' Industry Professional Posts: 17296 Location: So. Cal. Joined: February 9, 2002	. Have Fun and Enjoy the Music "Still Working the Problem"

RE: How do I double the voltage on diodes? Parallel or series?, posted on August 21, 2014 at 07:38:34
Tom Bavis Audiophile Posts: 961 Location: Upstate NY Joined: May 25, 2007	You need 1200V bare minimum - 1600V would be better... why not use 1000V diodes in series? I wouldn't trust 600V parts in series to take 1200V peak. And why an 8A rectifier? A 1A or 4A part will be easier to mount with no exposed terminals and will have less switching noise. MUR1100E or MUR4100E. 4100E is 25 cents in volume, 1100E is less.

RE: How do I double the voltage on diodes? Parallel or series?, posted on August 21, 2014 at 08:13:00
rick_m Audiophile Posts: 6230 Location: Oregon Joined: August 11, 2005	Series, but put a 0.001uF disc ceremic Cap across each of them to keep fast transients from exceeding their PIV ratings due to tolerance and strays. Rick

RE: How do I double the voltage on diodes? Parallel or series?, posted on August 21, 2014 at 08:38:51

Cleet Torres
Audiophile

Posts: 188
Joined: July 11, 2013

I have a boat load of them lying around. May as well use them right?

And I'll argue the switching noise comment - MUR860's are for all intends and purposes noiseless.

RE: How do I double the voltage on diodes? Parallel or series?, posted on August 21, 2014 at 09:27:09
cpotl Audiophile Posts: 1002 Location: Texas Joined: December 6, 2009	You could play safe and use three in series, if you are intent on using them. Chris

RE: How do I double the voltage on diodes? Parallel or series?, posted on August 21, 2014 at 11:50:43
Cleet Torres Audiophile Posts: 188 Joined: July 11, 2013	Mmm, any particular manufacturer # you would recommend? After giving it some thought I'm going to use three diodes per leg to accomodate voltage surges, so it looks the $$ I'm saving using what I got is going out on caps to allow me to use what I got. One cap per diode right? Thanks Cleet

RE: How do I double the voltage on diodes? Parallel or series?, posted on August 21, 2014 at 13:38:27
rick_m Audiophile Posts: 6230 Location: Oregon Joined: August 11, 2005	"One cap per diode right?" Right. The notion is to keep the voltage sane while the diodes have a chance to clear out their stored charge or start conducting. Actually it wouldn't hurt to parallel them with some large resistors also, something that runs about 10X their reverse leakage current. Best, Rick

RE: How do I double the voltage on diodes? Parallel or series?, posted on August 21, 2014 at 19:17:09

FenderLover

Prolly best to get 1kV rated caps.

Good luck!

Afterall is said and done, it's probably going to be a lot easier , posted on August 22, 2014 at 04:37:59
Cleet Torres Audiophile Posts: 188 Joined: July 11, 2013	and probably cheaper to just get some 1.2Kv Schottkys and plug them in. I don't have suitable ceramic caps lying around, so I'd be putting in an order to mouser anyways. Nevertheless, thanks for the info gents. Knowledge is always a good thing. Regards cleet.

Diode Voltage Ratings, posted on August 22, 2014 at 05:40:49
sony6060 Audiophile Posts: 1465 Location: USA Joined: August 8, 2014	I agree with Tom. For many years using a diode rated 2.5 times the PIV voltage reduces failures to about zero. This formula was originally found in Ham Radio Amateur Radio Handbooks regarding power supply design. 2 times the operating voltage for a bridge rectifier is the minimum value I would recommend too.

RE: Diode Voltage Ratings, posted on August 22, 2014 at 07:04:02
Cleet Torres Audiophile Posts: 188 Joined: July 11, 2013	So minimum 3 MUR860's in series per leg, preferably 4? Alternatively two 1Kv rated schottskys? Either way I need some bypass caps. High voltage schottkys (2Kv plus) are prohibitively expensive.

RE: Diode Voltage Ratings, posted on August 22, 2014 at 09:09:59
sony6060 Audiophile Posts: 1465 Location: USA Joined: August 8, 2014	Why not use 2x low noise UF4007 diodes per leg? I hear no performance difference in-between other 'high-end' diodes and the UF4007. The ultra low residual diode switching noise is attenuated by the circuitry downstream anyways.

RE: Diode Voltage Ratings, posted on August 22, 2014 at 13:30:17

FenderLover

If you really want to overbuild the rectifier --- I'd think about full-wave bridge using one UF5408 per leg. You may get away with no bypass caps. Noise level from a UF5408 is pretty low.

I have six in my 1968 Fender Bassman rebuild. Very reliable.

Good luck with your fix!

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RE: Diode Voltage Ratings, posted on August 23, 2014 at 09:56:34

Cleet Torres
Audiophile

Posts: 188
Joined: July 11, 2013

Well the idea was to change from a 5AR4 rectifier to solid state to allow myself to use a toroidal - cannot find any toroids with a 5v tap. And of course, not degrade sound quality in the process

But after considering having to series so many diodes and the cost of bypass caps I just went out and bought a new trans with a 5v tap and I'll use the 5AR4. Cost wise the toroid and all the caps and stuff will probably have cost as much if not more - and with my electronic skills, have resulted in a 911 call to put out the fire.

Moral of the story, sometimes a tube rectifier IS JUST more practical than solid state :-)

Thanks
Cleet

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How do I double the voltage on diodes? Parallel or series?

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