• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Help needed on tube rectification.

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W

w00t

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Joined 2003
#1
Hi everyone,

I have always loved the tube rectifier, but no knowledge of how to design a PSU based on it. Solid state powersupplies are very simple to design, but tube powersupplies have always baffled me.

The formula for calculating the DC produced through the tube confuses me the most.

Could someone explain more to me and also provide me with the formulas? Thanks a million! 😀 I have referred to many tube rectification schematics but they don't seem to have much relation with each other.
 
#3
Bas Horneman said:
Hopefully someone that has a "theory background" will help you out soon. 😉

In the meantime, have you heard of Duncan's Power supply simulator?

In case you have not ...it is very easy to use and free.

http://www.duncanamps.com/psud2/index.html


Good luck,
Bas
Click to expand...


Tried it with schematics I referred to and it seems to produce different voltages as stated in the schematic. Confuses me all the time. 😕

Thanks for the luck, I need it. 😀
 
#5
Bas Horneman said:
Try to measure the resistance of you power transformer and choke. And all other parts. And enter them.

The simulator is never far off in my experience.

Cheers,
Bas
Click to expand...


I'm sending in my order for custom wound transformers, so i would like to learn the theory before getting practical. 🙂

Cheers! 😀
 
#8
Rough rule of thumb:

A traditional transformer and fullwave rectifier (ie two diodes with a grounded centre tap) will give you about 1.2 times the AC voltage with a CLC filter. (ie 350-0-350 AC -> approx 420VDC) A diode bridge will give you about double that.

Under load, the voltage may shift around quite a bit, a bigger transformer gives better regulation. In PSU designer, make sure you have a current load that simulates the amps total current draw.

A "modern" tube rectifier like a GZ34 will give you a higher voltage than an older type like a 5U4, and also give a nice slow warm up.

Use a choke of 5-10H or more to give the best results.

Be careful of the value of the first capacitor. GZ34 will take 50uF or so, but 5U4 will not take more than a few uF.

Tell us more about the parts you have and what you are trying to build.
 
#9
ShiFtY said:
Rough rule of thumb:

A traditional transformer and fullwave rectifier (ie two diodes with a grounded centre tap) will give you about 1.2 times the AC voltage with a CLC filter. (ie 350-0-350 AC -> approx 420VDC) A diode bridge will give you about double that.

Under load, the voltage may shift around quite a bit, a bigger transformer gives better regulation. In PSU designer, make sure you have a current load that simulates the amps total current draw.

A "modern" tube rectifier like a GZ34 will give you a higher voltage than an older type like a 5U4, and also give a nice slow warm up.

Use a choke of 5-10H or more to give the best results.

Be careful of the value of the first capacitor. GZ34 will take 50uF or so, but 5U4 will not take more than a few uF.

Tell us more about the parts you have and what you are trying to build.
Click to expand...


When you say diodes I take it taht you are referring to tube diodes, right? 😀

Considering between 6X4 and GZ34 as the rectifier. I'm building a PSU for my 6SN7 preamp, wired SRPP. Need about 250V to 300V for it, in stereo.

Will have the coils(trannie, choke) custom made and buying the components I dont have. (caps, resistors..etc)

Thank you! 🙂
 
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