300V DC supply

Discussion in 'General Electronics Chat' started by magnet18, Mar 15, 2014.

  1. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
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    So i was at my local university surplus store, when I happened upon this 50 pound, steel and copper, PERFECT CONDITION box of awesome for an irresistible price!!

    it's by some company called Lambda, never heard of them, looks to be late 70s construction to my father (but that was ~20 years before i was born so judge for yourself)

    it's 125-300 volt DC supply, 200 mA, (I have no idea what for, tube stuff?) with another 7 volt 10 amp AC output (I'm guessing for tube heaters?)

    output voltages are actually very accurate, and I haven't loaded it yet but the voltage meter is spot on

    see attached images for all the good details

    First, does anyone know what this would have been used for?
    Second, does anyone have any ideas on what to use this for?


    EDIT
    found the manual online, bunkerofdoom.com/lit/Lambda_C-481M/Lambda_C281mnl.pdf
    looks like it was used for powering other monster tubes or radios
     
    Last edited: Mar 15, 2014
  2. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
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    couple more pics of the schematic
    (and the tubes in the dark)
     
    Last edited: Mar 15, 2014
  3. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    That thing's a lot older than the 70's....... I can't read the schematic very well, but I have no idea what it is.

    It appears to be some kind of resonant switching supply using vacuum tubes but I don't know what frequency.
     
  4. crutschow

    Expert

    Mar 14, 2008
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    It's a HV supply, typically to provide power for a tube amplifier B+ supply with the low voltage supply to power the tube heaters. Likely it was used to provide power for breadboard tube amps of various types during their design. Today there is seldom a need for such high voltages in solid-state design. Makes a nice room heater though.

    Lambda is an old power supply manufacture who is still in business as TDK-Lambda.
     
  5. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
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    Yea, it's a lambda c-281M supply

    I think we're gonna build a tube amp just so it has something to power! :)

    I still can't find the year it was manufactured though :p


    (schematic is in the pdf I uploaded, second post)
     
  6. GetDeviceInfo

    Senior Member

    Jun 7, 2009
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    We have a couple of RF tunnel heaters at work. B+ is 8Kvdc, while heaters are 6vac and run 150amp. I'd tend to agree that your lambda is a supply for power tubes.
     
  7. tindel

    Active Member

    Sep 16, 2012
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    That is 60W of awesome!

    That thing was obviously designed for tube circuitry... the low voltage supply is for the tube heaters and the high voltage to bias the tubes. This is a very valuable supply for someone designing tube amplifiers these days. Many people have to design their own supplies because these can be a bit difficult to find.

    Lambda is a great brand name too. They make some great power supplies. Very stable and low noise.

    Be sure to keep one hand in your pocket when using it! I don't have time to look too close to the schematic - but I'm assuming the supply is floating from earth ground to make it a bit safer for the user. If not, I'd make that mod before I used it.

    The big question: How much did it set you back!?!?
     
    #12 likes this.
  8. panic mode

    Senior Member

    Oct 10, 2011
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    i am sure parents are either worried or say "that's my boy..." :D
     
  9. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
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    $75!! :)

    (more charachters for the message requirement...)
     
  10. #12

    Expert

    Nov 30, 2010
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    Oh. My. Dog. It' a tube supply! Talk about 50 pounds of awesome!

    Congratulations!

    (I'm so jealous:()
     
  11. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Just think of all the NIXIE's & Dekatrons you can run; throw in a couple of PP 6L6's. Age- maybe late 1950's
     
  12. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
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    So doe anyone know any good tube amp/preamp kits/designs to build that this thing could power?
     
  13. #12

    Expert

    Nov 30, 2010
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    I like the Fender designs because I had to work on so many of them. With that supply, you could go as far as a pair of 6L6's, maybe even a quad of them.

    Kits? We don't need no stinking kits. :D
     
  14. SgtWookie

    Expert

    Jul 17, 2007
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    Actually, I have some really monster tubes I've been meaning to make an audio amplifier out of ... When you find out how much those things cost, maybe you'll consider selling the supply to me? :)
     
  15. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
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    Haha, may not need a kit, but I at least need a schematic ;)

    We're considering it, if you're serious pm me
     
  16. #12

    Expert

    Nov 30, 2010
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    Give me a clue. I only have a few hundred tube amp schematics.
     
  17. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
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    and thousands more to wade through on the internet :p


    I could use some help narrowing things down,
    do you know anything that is stereo, <= 325 volts/200mA (this supply), along the lines of being used with the record player in the living room (not blasting guitar in the garage)?

    preferably not dozens of tubes, just a few, simplicity of the build is a factor too
     
  18. #12

    Expert

    Nov 30, 2010
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    Bad news. Most of my stuff is for musical instruments. Not stereo.
    Also, phonographs need frequency defining circuits (RIAA).
    Back to the old google.:(

    correction: ALL of my stuff is musical instrument amps.
     
  19. bertus

    Administrator

    Apr 5, 2008
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    magnet18 likes this.
  20. magnet18

    Thread Starter Senior Member

    Dec 22, 2010
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