• 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.

Diode tubes in parallel

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Ok, let me ask it another way. Is the voltage drop of the diode tube simply a function of resistance or is it a constant? What is the cost of thermal emission?

Don't worry about confusing me, i'll figure it out. ... but yes my theory is weak, that is why I am here.
 
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Ok, let me ask it another way. Is the voltage drop of the diode tube simply a function of resistance or is it a constant? What is the cost of thermal emission?

Don't worry about confusing me, i'll figure it out. ... but yes my theory is weak, that is why I am here.

The current rating of the PT AC is an RMS current based on the RMS voltage and since the current is flowing in series through the rectifier and into filters creating a DC (RMS) current in series, whatever is flowing there is also flowing through the rectifier and PT. Don't design a power requirement higher than the rectifier is rated for and what the tranny is spec'd at and you will live happily ever after.
 
If diode tubes are run in parallel I am guessing they would have the same problem as power tubes in parallel? One tube running away. Would doing this require current regulation on each tube?
I would review the assumption that there is a problem needing a solution here.

Valve diodes vary with respect to the resistance of each half. The inherent resistance in each diode automatically assists balancing, whether the (typical) 2 diodes in a valve, or two diodes in different valves, are operated in parallel. You will typically find no vintage use of balancing resistors in larger power amps that use two valve diode parts.

If you were concerned about balancing, then like output stage valves, you should aim to test the diode on-voltages for a specific current as an indicator of diode matching. Even that test is just an indication, as the current in a diode is typically a quite peaky short duration waveform where the current can be quite high.
 
Why is it that there is none of these design tools that run on current operating systems?
The PSUD2 software is imho the easiest basic tool for you to spend time and effort to configure to help you through understanding some of your many queries. The app allows you to add a diode that may not have a default model, and allows you to appreciate how the resistance of the power transformer, along with the valve diode resistance, and the filter capacitance and load, influence the current in the diode. It does not allow two different diodes operating in parallel to be simulated such that individual diode currents can be discerned, but you can change diode parameters and see how that changes rectifier current, and with some understanding of how two different diodes would operate, you can deduce the estimated balance.

The simulation of valve diodes starts to become technical, and so would the measurement of diode operating parameters in a tester, so you may have quite a learning curve ahead of you if you don't have a good grounding in electronics. There are many forums and threads on PSUD2 usage, and on-line tutorials, and many on-line power supply design books and articles, that should keep you busy if you were interested to making the effort.
 
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The PSUD2 software is imho the easiest basic tool for you to spend time and effort to configure to help you through understanding some of your many queries. The app allows you to add a diode that may not have a default model, and allows you to appreciate how the resistance of the power transformer, along with the valve diode resistance, and the filter capacitance and load, influence the current in the diode. It does not allow two different diodes operating in parallel to be simulated such that individual diode currents can be discerned, but you can change diode parameters and see how that changes rectifier current, and with some understanding of how two different diodes would operate, you can deduce the estimated balance.

The simulation of valve diodes starts to become technical, and so would the measurement of diode operating parameters in a tester, so you may have quite a learning curve ahead of you if you don't have a good grounding in electronics. There are many forums and threads on PSUD2 usage, and on-line tutorials, and many on-line power supply design books and articles, that should keep you busy if you were interested to making the effort.

Thanks, it sounds worth the effort, but to do so I would have to install an old 32 bit OS in a virtual machine. Being that I am an IT guy it is easy enough to do, so I guess I have no excuse. I will need VMWare workstation so I have a plan. The problem is it costs $250. I am just wondering why no one has bothered to update the software. I have been using everyciruit but it is very limited, especially with tubes there is pretty much nothing there. I was a bench tech 30 years ago, but that is a long ways from understanding tube amp design. Which is why I am here asking stupid questions, LOL!



EveryCircuit - Home


VMware Workstation 15.5 Pro
 
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I can run PSUD2 without 32-bit environment. In case you have other reasons for needing a virtual machine, perhaps you can use VMware’s Workstation Player:

“VMware Workstation Player is an ideal utility for running a single virtual machine on a Windows or Linux PC. Organizations use Workstation Player to deliver managed corporate desktops, while students and educators use it for learning and training.

The free version is available for non-commercial, personal and home use. We also encourage students and non-profit organizations to benefit from this offering.”

Regards, Gerrit
 
I don't want to confuse you.

"...would two tube diodes in parallel cut the dropping voltage in half or would I just get the same dropping voltage but twice the current?" suggests you need basic theory, not math.


take this gold nugget of advice,

i will first know the load current required, then look at the tube and find out, is this tube enough? if answer is no, then look at another tube rect for one that fits the bill...
 
If diode tubes are run in parallel I am guessing they would have the same problem as power tubes in parallel? One tube running away. Would doing this require current regulation on each tube? Would small plate inductors on each tube solve this problem well enough? What kind of filter cap max increase could be applied?


Examples of paralleled vacuum rectifiers are scattered all thru this forum & have been used successfully for many years commercially. I've never seen any one of them using balancing resistors. Gas rectifiers are in a totally different world & there are several methods of balancing.
What is your application, do you have a schematic?
 
The forerunners of this thread have passed thru several reincarnations over the past two years, I checked it out. Under normal circumstances we would see some progress but the questions being asked seem to move in circles.
The original poster needs some basic education, the kind found in books for Newbies to electronics. For example, the soft cover book 'Old Time Radios Restoration & Repair' by Joseph Carr is a very good starting point. It is written with Newbies in mind. That way the person asking for advice can at least come to the forum & ask questions that make sense. Without a basic knowledge progress is difficult at best.
This book in spite of being called a Radio book contains whole chapters on rectifiers & power supplies, audio amplifiers of various kinds & a good information in vacuum tube operation. There are other books available for Newbies as well.

All available on the iNet at reasonable cost. Something well worth investing ones time if new at this activity.:)
Trying to piece together a working knowledge of electronics on this forum alone is next to impossible,:)
 
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