The Official Dual Rail Thread

[mooreamps]

Oh. OK. Good for you.

Do you also wear shoes, drive a car, use a computer? Keep on, then. Those are good for you. Hope that continues to work OK.

You have a copy of the RDH. You look up this one......

[R.G.]

You have a copy of the RDH. You look up this one......

Rocket Drive Handbook????

You did invite me to ask my friendly neighborhood rocket scientist whenever I wanted to know something. I like that offer, thank you for it, and am going to take advantage of it.

You see, the way this works is this: I don't think I know everything, by any means; when you make a technical assertion that doesn't seem to make sense to me, I'm going to ask you to explain it, in English, written down, in public.

And if the explanation contradicts the information I find elsewhere, I'm going to ask you to explain the differences. I'm curious by nature, and I'm always ready to learn something new. Especially when my friendly neighborhood self-professed rocket scientist has offered in public to explain things to me.

So Grandmaster, howwzat work? I bow to your greater understanding of the universe at large, and seek enlightenment.

[mooreamps]

Produces two separate rails of equal voltage. I don't do the current transformers anymore. A UL shunt regualtor works just as good...

[R.G.]

Produces two separate rails of equal voltage. I don't do the current transformers anymore. A UL shunt regualtor works just as good...

Actually, I already know **what** it does. What I was asking you was **how** it works. Well, to be truthful, I also wanted to know why you thought this was adding something to the discussion.

[mooreamps]

Actually, I already know **what** it does. What I was asking you was **how** it works. Well, to be truthful, I also wanted to know why you thought this was adding something to the discussion.

The diodes in the middle act as a voltage doubler circuit ; embedded within the twin bridge circuit...

-g

[R.G.]

The diodes in the middle act as a voltage doubler circuit ; embedded within the twin bridge circuit...

That's a manful guess, all right. But can you walk me through the circuit and explain how those six diodes make any kind of voltage doubler?

The diodes to ground and the combination of diodes at the top look to me like they make up a single full wave bridge rectifier. The fact that both sides of the positive-going diodes have a solid state diode and a tube rectifier section in series makes no difference at all in how the full wave rectifier circuit works. All that does is lower the eventual DC voltage by the losses in the tube rectifier. At least that's what I think. 'Splain how I'm wrong about that, OK?

How would it be different if I shorted each one of the two diodes connected to the anodes of the tube rectifier?

While I'm out here just wondering out loud, is there anything at all connected to the transformer center tap? Anything? Or does it just float around in the breeze? Could we get exactly the same operation if we just cut off that center tap at the transformer?

[mooreamps]

That's a manful guess, all right. But can you walk me through the circuit and explain how those six diodes make any kind of voltage doubler?

A Manful Guess ???? Are You F^@&ng kidding me ? I would take me about half an hour in front of a white board to define the 9 phase states of this circuit....

Do you also wear shoes, drive a car, use a computer? Keep on, then. Those are good for you.

Let me guess, you couldn't find it inside the RDH. When I find my shoes, I'll get back you ya.......

-g

[Wilder Amplification]

If I'm reading that schematic properly, it looks like the center tap would go to the lower B+ rail, which by "design" makes it a FWB doubler, but a FWB doubler isn't really a doubler at all since using a FWB rectifier across the whole winding will "double" the CT voltage.

Also...with a 600V secondary you'd actually end up with around 840VAC rectified and filtered...not the 600VDC that's shown on the schematic.

[R.G.]

A Manful Guess ???? Are You F^@&ng kidding me ? I would take me about half an hour in front of a white board to define the 9 phase states of this circuit....

While we're at it, since it would take you half an hour in front of a white board to define those nine phase states, would you write down what you mean by "phase state"?

If that would take less than half an hour for you, of course. I'll sit here with bated breath.

Oh, wait a minute. Never mind, I guess it would take you more than half an hour. Sorry.

I once watched and took notes while a fellow derived Maxwell's Equations on a black board (this was before whiteboards) in 50 minutes, start to finish. So how much longer could it take ... you... to write down nine "phase states" of six diodes, four of which are in two series pairs? I know I can concentrate for at least 50 minutes; I'll give you the same attention span I paid to Maxwell.

Let me know when you start.

Let me guess, you couldn't find it inside the RDH.

I didn't look. I used to design power supplies for a living. I know quite a bit about how rectifier setups work. Not everything, but enough to feed the family for a few years, and to recognize a full wave bridge when I see it. But of course, I don't need to resort to phase states to understand their operations, so maybe that's an unfair advantage I have.

Just as an aside, there isn't one THE RDH, if by that you mean the Radiotron Designer's Handbook. I have the third and fourth editions in hardcopy.

And again, what *exactly* do you mean by "phase state"?

When I find my shoes, I'll get back you ya.......

Don't spend too long on it. You have all those phase states of six diodes to write out, remember. Maybe you should just pull on a pair of boots in case it gets too deep.

Just to be thorough, here are the questions I asked a couple of posts back that you just kind of ducked responding to. Could you give them a go? If you have any idea about answers, that is. My questions are in italics:
1. The fact that both sides of the positive-going diodes have a solid state diode and a tube rectifier section in series makes no difference at all in how the full wave rectifier circuit works. All that does is lower the eventual DC voltage by the losses in the tube rectifier. At least that's what I think. 'Splain how I'm wrong about that, OK?

2. How would it be different if I shorted each one of the two diodes connected to the anodes of the tube rectifier?

3. While I'm out here just wondering out loud, is there anything at all connected to the transformer center tap? Anything? Or does it just float around in the breeze?

4. Could we get exactly the same operation if we just cut off that center tap at the transformer?

As before during our discussion of how fuses work, I really, really do want to know how my understanding of line frequency rectification is flawed. I am perfectly willing to admit I'm wrong if you show the correct reasoning to me.

[imaradiostar]

Gary, please help us understand. What, if anything, does the high voltage secondary center tap connect to?

jamie

[R.G.]

If I'm reading that schematic properly, it looks like the center tap would go to the lower B+ rail, which by "design" makes it a FWB doubler, but a FWB doubler isn't really a doubler at all since using a FWB rectifier across the whole winding will "double" the CT voltage.

Yeah, that's right. I was trying to see if Gary could be led through realizing that he didn't draw the schemo correctly. Dang. Now the surprise is spoiled!

Also...with a 600V secondary you'd actually end up with around 840VAC rectified and filtered...not the 600VDC that's shown on the schematic.

Yep, you'd get a pot full more than 600V. The variable losses in the tube rectifier make it soggier than that, but close.

I was going to get him to lambast me about how it actually worked and then lead him into that one. Near as I can tell, he probably gets about 600 and 300, and so he made the intuitive leap to the secondary AC being the same as the output DC. Which means he either doesn't know how a rectifier/capacitive filter works or can't articulate it if he does know.

This is so naughty of me. I should be more tolerant. But shhhhh... let's see what he makes out of "phase states of a diode".

[Wilder Amplification]

Oops...sorry about that.

I'm also curious about diode phase states...perhaps it's part of the new electronics theory that Gary "created" (hereby known as the "Moore Theory")?

[imaradiostar]

Let me google that for you

No useful results that I could see. Maybe someone could explain it for us.

jamie

[imaradiostar]

What does the "b" in the middle of the diodes next to the filter caps mean? I'm not familiar with that symbol.

jamie

[Steve Conner]

It stands for "backwards" to indicate the diodes should be installed the wrong way round.

Or maybe "bleh".