Mixing diodes in a bridge

Prune · 18th September 2004, 09:41 PM

I have three HVR-1X 4 and one HVR-1X 3 (they are 9 kV rectifiers). Will I have a problem if I make a bridge rectifier out of these? The difference is that the forward drop on the 4 is 9 V, whereas on the 3 it is 14 V.

Swedish Chef · 19th September 2004, 05:52 PM

What are you going to use these diodes for? If doing a HV (> 1 kV) supply, consider using a diode-capacitor ladder configuration instead.

/Magnus

Sch3mat1c · 19th September 2004, 06:14 PM

As long as you use them symetrically it should be okay... i.e., have the opposite legs of the FWB conduct so there's a 9V and 14V in series. Then do the same on the other half wave.

Tim

Prune · 19th September 2004, 06:50 PM

That's what I thought. Unfortunately I have three of one kind, and one of the other, so it's impossible to get symmetry. I guess I'll stick with the 1N4007 chains; they can handle more current anyway (the HV diodes are only rated to 350 mA).

Swedish Chef, paralleling capacitors/resistors is not necessary for diodes produced recently, as now most manufacturers design them so that they can be put in series without other components. I read somewhere this, where as the diode begins to be overvoltaged and before it avalanches, its leakage increases, equalizing the chain. Capacitors/resistors may actually worsen the setup.

Swedish Chef · 19th September 2004, 11:17 PM

Prune,

I was not talking about stringing diodes in series and then compensate the voltage on each diode, but rather to just make an diode/capacitor voltage multiplier to reach high voltages (in your case up to 30-35 kV). But I still don't have a clue of what you are trying to build or if it is for audio or anything else.

/Magnus

Prune · 20th September 2004, 05:58 AM

It's described in these threads:
Plasma/ionic
Transformer question

Sch3mat1c · 20th September 2004, 10:19 PM

D'oh! With 5V more voltage drop in one leg, you'll get slightly more voltage on one half cycle. If there's like 100V of ripple, you won't notice it, but if it's as low as 2V at the rectifiers, it'll be entirely through one pair of diodes (half wave).
You could use a 5V zener backwards in the string to increase Vf. When the string is off, the zener would be forward so it doesn't change PIV or anything.

Tim

18th September 2004, 09:41 PM	#1
Prune Account Disabled Join Date: Mar 2003 Location: Vancouver	Mixing diodes in a bridge I have three HVR-1X 4 and one HVR-1X 3 (they are 9 kV rectifiers). Will I have a problem if I make a bridge rectifier out of these? The difference is that the forward drop on the 4 is 9 V, whereas on the 3 it is 14 V.

19th September 2004, 05:52 PM	#2
Swedish Chef diyAudio Member Join Date: Jun 2004 Location: Stockholm	What are you going to use these diodes for? If doing a HV (> 1 kV) supply, consider using a diode-capacitor ladder configuration instead. /Magnus __________________ "Knowing what to do but not why is no use in a changing world" - The Art of Sound Reproduction

19th September 2004, 06:14 PM	#3
Sch3mat1c diyAudio Member Join Date: Jan 2003 Location: Milwaukee, WI	As long as you use them symetrically it should be okay... i.e., have the opposite legs of the FWB conduct so there's a 9V and 14V in series. Then do the same on the other half wave. Tim __________________ See my Electronics webpage -- the home of Vacuum Tube Drag Racing. The key to being a successful Audiophile: "I reject your reality and substitute my own!"

19th September 2004, 11:17 PM	#5
Swedish Chef diyAudio Member Join Date: Jun 2004 Location: Stockholm	Prune, I was not talking about stringing diodes in series and then compensate the voltage on each diode, but rather to just make an diode/capacitor voltage multiplier to reach high voltages (in your case up to 30-35 kV). But I still don't have a clue of what you are trying to build or if it is for audio or anything else. /Magnus __________________ "Knowing what to do but not why is no use in a changing world" - The Art of Sound Reproduction

20th September 2004, 10:19 PM	#7
Sch3mat1c diyAudio Member Join Date: Jan 2003 Location: Milwaukee, WI	D'oh! With 5V more voltage drop in one leg, you'll get slightly more voltage on one half cycle. If there's like 100V of ripple, you won't notice it, but if it's as low as 2V at the rectifiers, it'll be entirely through one pair of diodes (half wave). You could use a 5V zener backwards in the string to increase Vf. When the string is off, the zener would be forward so it doesn't change PIV or anything. Tim __________________ See my Electronics webpage -- the home of Vacuum Tube Drag Racing. The key to being a successful Audiophile: "I reject your reality and substitute my own!"


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19th September 2004, 06:50 PM	#4
Prune Account Disabled Join Date: Mar 2003 Location: Vancouver	That's what I thought. Unfortunately I have three of one kind, and one of the other, so it's impossible to get symmetry. I guess I'll stick with the 1N4007 chains; they can handle more current anyway (the HV diodes are only rated to 350 mA). Swedish Chef, paralleling capacitors/resistors is not necessary for diodes produced recently, as now most manufacturers design them so that they can be put in series without other components. I read somewhere this, where as the diode begins to be overvoltaged and before it avalanches, its leakage increases, equalizing the chain. Capacitors/resistors may actually worsen the setup.

20th September 2004, 05:58 AM	#6
Prune Account Disabled Join Date: Mar 2003 Location: Vancouver	It's described in these threads: Plasma/ionic Transformer question

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