vaccuum tubes

Discussion in 'General Electronics Chat' started by electronis whiz, Aug 6, 2011.

  1. electronis whiz

    Thread Starter Well-Known Member

    Jul 29, 2010
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    i have 4 old vacum tubes from an old table end table style record player. 2 are siemans the other i'm unsure of the others brand. one of the siemans tubes is black on part of the inside is this one bad?
    is there any reson i should hold onto these? can i do anything with them i cant do with a transistor, traic, draic. they all have 9 pins what are all of these pins do?

    the small one apeares to be a SAG ECC83S preamp. both siemans apear to be stareo tubes. the blackened siemans has part #ez81, then a siemens EL84, then a what looks like sonotone EL84-0bq6. apears to be a power output pentode (what is a pentode?)
    i'm thinking about just sticking them in a project case and putting a smalll LED under each of them then conecting all the leds in it to a usb cable for power.
     
    Last edited: Aug 6, 2011
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    Tubes commonly used power supplies with DC voltages ranging from 150V to 500V, some even higher. The multiple leads are not all connected in most cases, but things like pentodes and dual triodes would have many of them connected. Go to Wikipedia and search around on the articles about vacuum tubes. Lots of information there to get you started in understanding why they are no longer popular in DIY/amateur projects. Audiophile projects sometimes suggest using them for preamps and such. They still see lots of use in high power radio transmitter applications as well. Unless you still have the packages for them and can assert they are new/unused, you will not have much luck getting them sold to anyone who still uses them.

    Is there a marking on them. A6U8 or similar?

    (edit)Well, if you go back and edit the original post then my question on what kind of tube markings they have will seem rather silly won't it?
     
    Last edited: Aug 6, 2011
  3. electronis whiz

    Thread Starter Well-Known Member

    Jul 29, 2010
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    they have all been used i think the one with the black may be burned out.
     
  4. Adjuster

    Well-Known Member

    Dec 26, 2010
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    Typically a record player using Pro-Electron coded tubes (valves) might have used an EZ81 rectifier and a pair of EL84 output pentodes - possibly in a push-pull stage for fairly loud mono reproduction. The ECC83 double triode was very commonly used in the input stages of audio gear of this kind.

    The pentode was a type of tube which had five electrodes. It had certain advantages over the triode, particularly for high-frequency amplification, and also for power output stages. Large triodes (not little ones like ECC83) could also be used as power amplifiers with potentially very good quality, but rather high power consumption. http://en.wikipedia.org/wiki/Pentode

    Dark colouration on the envelope of a tube may be the result of electrode material being evaporated and deposited on the glass during extended use, but could also be due to "gettering" material deliberately put there during manufacture to improve the vacuum.

    Mullard-Philips valve numbering: http://en.wikipedia.org/wiki/Mullard-Philips_tube_designation

    EZ81 rectifier: http://www.r-type.org/exhib/aaa0522.htm

    EL84 power pentode: http://www.r-type.org/exhib/aaa0028.htm

    ECC83 double triode:http://www.r-type.org/exhib/aaa0046.htm
     
  5. #12

    Expert

    Nov 30, 2010
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    Usually, white is the bad color and black is good. Photos would help.
     
  6. SgtWookie

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    Jul 17, 2007
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  7. electronis whiz

    Thread Starter Well-Known Member

    Jul 29, 2010
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    thanks everyone, it was cool to learn some more about vucum tubes.
    but i have all kinds of transistors that i know more about than i do tubes. it would also be hard for me to get make a 120+V DC power source for them, and i know nothing about the pinouts on tubes, + i like to keep all my projects low voltage DC usily 20V DC is as high as i will use.
    so i think i will probly just make my usb project with them or recycele them. (just wondering how brakable are vacum tubes. if making this usb idea boud just be a bad idea.) (i was thinking just drill holes in a project box and put the tubes in the holes with an led under each. it would be kind of like a nerdy night light to set on my desk.)
     
  8. SgtWookie

    Expert

    Jul 17, 2007
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    Well, tubes/valves are getting to be hard to find - the good ones, anyway. Hold on to them; as you get into electronics more, you may want to try building an audio amplifier with them. Documentation is available on the Web if you perform searches.

    The ECC83 is equivalent to the US 12AX7 developed by RCA in the 1940's. They're still very popular with musicians.
    Here's a Wikipedia entry on them:
    http://en.wikipedia.org/wiki/12AX7
    Here is a site that has LOTS of datasheets on tubes:
    http://tubedata.milbert.com/
     
  9. Wendy

    Moderator

    Mar 24, 2008
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  10. #12

    Expert

    Nov 30, 2010
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    I did 2 vacuum tube amps for my musician friend after knowing him for 30 years. I sorely regret throwing out the tubes I had leftover from doing TV work. Keep them in a box gathering dust. They don't rot like electrolytic caps.
     
  11. bertus

    Administrator

    Apr 5, 2008
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