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Old 21st June 2005, 02:45 AM   #361
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Quote:
really liked the movie China Syndrome.
Alas the infamous "elephants foot" fuel lava under the Chernobyl reactor...... Nasty stuff!

Mark
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Old 21st June 2005, 04:17 AM   #362
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Quote:
Originally posted by Zero Cool
Actually, I was at a surplus store in Florida a few years back that had a GIANT knife switch. i mean this thing had to be at least 36" long and 24" wide and had a geared handle mechanisim that would spin up a flywheel system that would slam the contacts closed and latched once the handle got all the way down. really cool device!

ZIIIIPPPP CLACK!

I think i sat there for at least 15 minutes playing with the thing. i should have bought it but it was expensive and HEAVY and i was leaving on a plane in a few hours. would have made a KILLER movie prop. I wish i would could have at least taken a photo of the thing. never seen another one like it. I mean it was BIG!

Maybe that should be my next project, duplicate that thing....

Zc

Ok now you guys got me thinking about this thing again. If anyone find any photo's of something like this, please let me know.

This thing wasnt actually a knife switch if i remember correctly, it was just a large handle/gear/flywheel driven switch, with DPDT contacts and BIG round contacts, Each one was at least 2-3" in diameter.

I dont remember all of the working details. But there was a large handle that operated a gear driven flywheel, when the handle reached the full posistion, it quickly kicked out a sort of a dogged clutch mechanism that engaged a shaft that moved the contacts. once the contacts had closed fully, the remaining flywheel action was used to ratchet the contacts tight.

Pulling the handle back at that point, released the latch and pulled back the clutch and started the flywheel moving in the other direction with the proccess repeating to move the contacts to the other side.

It made a very distinctive noise zzzzZZZZZPPPPPPPP CLACK! ztztzttztzttztzttttt.

DANG i wish i had bought that thing.

Zc
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Old 23rd June 2005, 08:17 PM   #363
lgreen is offline lgreen  United States
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Default Monster

I guess the monster will be a lot bigger than this amp (posted on on post 2778 of the Krell Clone thread)?

OK, its the biggest amp I've ever seen.
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Old 23rd June 2005, 09:12 PM   #364
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Yes, I believe the PM is a little bigger than that.

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Old 23rd June 2005, 09:17 PM   #365
jleaman is offline jleaman  Belgium
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Default Re: Monster

Quote:
Originally posted by lgreen
I guess the monster will be a lot bigger than this amp (posted on on post 2778 of the Krell Clone thread)?

OK, its the biggest amp I've ever seen.

Wonder if it has wheels ?
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Old 28th June 2005, 02:30 AM   #366
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Okay...a progress report from the hinterlands.
My wife--kind soul that she is--took this past Friday off so as to take over the baby duties so I could get some time in on the Monster front end.
Is it done? No.
But it's pretty well firmed up.
I've got two more things I want to do, but I don't anticipate any problems (famous last words...). Just a little straight-forward engineering.
I had hoped to stick to an isolation transformer and voltage doubler for the power supply. It was going to be rather a tight fit to meet Nelson's specifications with the rail at that level, but I think the path of wisdom is going to be to go with a higher rail after all. The tubes I'm using can take more rail voltage easily, so that won't be a problem.
As I've noted from the beginning, the voltage swing Nelson requested wasn't going to be a problem, but the current...ah, the current...tubes and current aren't exactly the best combination. My first impulse was to use the 6AS7/6080 for the follower output stage. I really, really wanted to make it work. However, the voltage swing and plate dissipation were going to be high enough that I was uncomfortable given the limitations of the tube. This led me to cast about for another candidate.
Bear in mind that I am dead set against using odd tubes, difficult to find tubes, absurdly expensive tubes, or any tube whose manufacture involves palladium, moon dust, or cat gut. That limits things a bit. Even some tubes I thought might be good possibilities are getting scarce.
(Jeez, anyone tried to source a decent 6SL7 recently? Not that it's a good output tube, but I had figured that it would be around for a while. All I saw were "no name" brands, and only a limited selection of those; cheap, yes, but how good are they? How reliable? I hate to say it, but I may have to give up on tubes entirely. This is getting to be a pain for someone with no more resources than I have.)
Anyway, to make a long story short, I have selected an output tube. The circuit seems to be working well on the bench. As soon as I can get another day, perhaps two, I think I can wrap this thing up.
No promises as to when that will happen, though. Might be this coming weekend, might be next year. I'll try to nail it as soon as possible, though, and that's a promise.

Grey
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Old 28th June 2005, 07:42 AM   #367
owen is offline owen  United Kingdom
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Grey - sounds a little mad, but how about either a 6bm4 if you need a sensitive input, or an EL84 (common, cheap, reliable, still produced...) for a less sensitive input?

It all depends on topology with tubes to get current - either multiple parallel tubes, or a voltage gain stage with a current follower (that could be a transformer...

Just some thoughts...

Owen

longterm tube-head moving to the dark side of smoke and mirrors.....
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Old 28th June 2005, 03:47 PM   #368
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Mr. Pass: I just looked through this thread and realized we never posted a schematic of the output section. Would you do the honors? It would serve to put this beast into perspective and to show what Grey is working with…

-Casey Walsh
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Old 28th June 2005, 10:00 PM   #369
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I didn't realize it had not been posted.

Here it is:
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Old 29th June 2005, 07:39 AM   #370
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Assuming Mr. Rollins's tube front directly drives the output stage, as i do not see driver devices, what will be the target for the slewrate of the amplifier ?

28 output devices surely need quite a bit of current to give them enough speed ?
Has there ever been a fully balanced hybrid, or "would" this be a novelty ?
Bless to cheap IRF's, building such an output with Lateral's would have been a painfull event.
(try to find a 6SQ7 nowadays)
Thanks for the poking, Casey.
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