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Hybrid Graetz Bridge

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alexg

alexg

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Joined 2005
#1
I built a PP KT88 with SS rectification and there is a huge turn on thump.

I tried ICLs, reducing PSU capacitance, caps across the switch and other ways to remove the thump and I am very unsuccessful. I don't want to build a mute circuit.

I have a 5ar4 rectifier which is rated at maximum of 250ma at 375VAC input. (I only have space for one rectifier tube on my chassis).

I need more than 250ma, would using a hybrid Graetz bridge increase the current capability of the 5AR4?

Thanks.
 
#2
alexg said:

I need more than 250ma, would using a hybrid Graetz bridge increase the current capability of the 5AR4?
Click to expand...

No, but you could put a single 6cg3 damper diode after the bridge for a slow turn on. I think they are rated for about 350mA DC, and would drop about 20V. There may be others too.

Sheldon
 
#3
Re: Re: Hybrid Graetz Bridge

Sheldon said:


No, but you could put a single 6cg3 damper diode after the bridge for a slow turn on. I think they are rated for about 350mA DC, and would drop about 20V. There may be others too.

Sheldon
Click to expand...

Thanks Sheldon.

Can I parallel two 5ar4 to get more than 250ma?
 
#4
Well, I've seen the plates paralleled, so by extension it should be fine to parallel two tubes (4 plates). But if you are going to do that, just parallel the plates in each tube and go back to the the hybrid bridge with two tubes. And if you are going to do that, just use two damper diodes like a 6AU4.

Sheldon
 
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