380VAC Transformer for tube amp

Discussion in 'General Electronics Chat' started by NotBigfoot, Aug 6, 2014.

  1. NotBigfoot

    Thread Starter New Member

    Aug 6, 2014
    7
    0
    Hello,

    I am building a 5W tube amp (Octal Fatness)

    Now my question is what kind of transformer i would need for this amplifier (i live in the netherlands so primary is 230vac)

    And where would i purchace this transformer?

    Thanks in advance!

    Nick
     
  2. Veracohr

    Well-Known Member

    Jan 3, 2011
    552
    76
    Looks to me like you would want about 357V on the secondary, considering the point after the diodes is 356V.

    Regardless, I don't know where in your country to buy transformers, but they typically are specified by secondary voltage rating and current. You need to figure out how much current it will require.
     
  3. alfacliff

    Well-Known Member

    Dec 13, 2013
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    seems like a strange place for the switch.
     
  4. NotBigfoot

    Thread Starter New Member

    Aug 6, 2014
    7
    0
    Yeah the switch is in a strangr place, ill probably place it in front of the transformer.

    But im looking for a model of transformer that will suffice (if possible), or maybe even a webshop where to acquire the transformer

    Thanks!
     
  5. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,998
    745
    There is a valve transformer company in UK, they do a 230/350-0-350v, and a 410v. Website
     
  6. jmoffat

    Member

    Jul 18, 2012
    42
    1
    Are you sure about those resistor values? If the 238V was shorted to ground you would be drawing less than 1 watt.
     
  7. NotBigfoot

    Thread Starter New Member

    Aug 6, 2014
    7
    0
    Hello,

    I've decided to build my own transformer because i cant find one with the right specifications for a reasonable price.

    Now my question is:

    Where can I order a transformer kit?
    or
    Where can I order the parts I need to build the transformer?

    Thanks in advance!

    Nick
     
  8. mitko89

    Member

    Sep 20, 2012
    123
    19
    I was working in a company that was specialized in design and manufacture of transformers. If you provide some specification I can give my man there a call and ask him how much would it cost. I am not sure I am allowed to provide the site of the company. If you want to know it write me a PM and check it yourself.
     
  9. Papabravo

    Expert

    Feb 24, 2006
    10,148
    1,791
    I've never heard of a transformer kit. There are two approaches you could take.
    1. Locate a suitable torroid core
    2. Fabricate a core from multiple pieces of sheet steel
    Once you have a suitable core you use enameled magnet wire to wind the transformer. Then comes testing and finishing.
     
  10. MrChips

    Moderator

    Oct 2, 2009
    12,447
    3,363
    There are transformers and there are transformers.

    Tell us what you want to transform with numbers, voltages, currents, wattage, frequency.
     
  11. NotBigfoot

    Thread Starter New Member

    Aug 6, 2014
    7
    0
    I need a transformer P230V S350-400V about 10-20W

    but I have a hard time finding a suitable transformer to do the job
     
  12. inwo

    Well-Known Member

    Nov 7, 2013
    2,433
    315
    Are you in USA?

    Shouldn't be hard to find something. Or use two.

    One time use?
     
  13. NotBigfoot

    Thread Starter New Member

    Aug 6, 2014
    7
    0
    I live in Europe, One time use in Tube amplifier
     
  14. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,670
    804
    Saying in which country would be helpful. There are a lot of companies that will make it for you, and a 20W should be pretty cheap.
     
  15. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,553
    2,375
    If in N.A. you could pick up a Toroid from Antek (Jonango on ebay) that has the closest specs, this will already have the primary and you can either add to or remove a secondary winding to increase the particular voltage you need.
    Also small aux windings can be added if needed.
    I see you are in Europe so look for a Toroid manuf there.
    Max.
     
  16. NotBigfoot

    Thread Starter New Member

    Aug 6, 2014
    7
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    Sorry, I live in the Netherlands
     
  17. alfacliff

    Well-Known Member

    Dec 13, 2013
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    checkout "control transformers" I am not too sure of the european standards, but here we can get control transformers for industrial use pretty reasonable and from 5 to 5000 watts or more.
     
  18. MrChips

    Moderator

    Oct 2, 2009
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  19. kubeek

    AAC Fanatic!

    Sep 20, 2005
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  20. bance

    Member

    Aug 11, 2012
    315
    34
    RS components used to do a transformer kit with a pre-wound primary I think. They come up from time to time on e-bay, otherwise you can canibalise an existing transformer. google diy transformers for info....

    HTH Steve.

    http://lmgtfy.com/?q=diy+transformers
     
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