Alternatives for MJ4502 and LM301A.

Discussion in 'The Projects Forum' started by prashanthb, Aug 10, 2015.

  1. prashanthb

    Thread Starter Member

    May 17, 2015
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    4d12e69a3570ac3f1f2d394edc859dcd257635de_large.jpg

    Please suggest alternatives for MJ4502 and LM301A.
    I am finding a lot of counterfeit LM301. Difficult to trust the local offline sellers.

    Another question : LM317K is expensive. So can I club 3 lm317T in parallel. Will it behave properly with higher power handling capacity ?

    Thank you.
     
  2. prashanthb

    Thread Starter Member

    May 17, 2015
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    Can 2SA1302 or MJL21193 be used as substitute ?
     
  3. ian field

    Distinguished Member

    Oct 27, 2012
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    That's a very old design and it may be difficult to find components as bad as those old relics.

    Were you able to find a datasheet for the PNP power transistor? A 2N2955 springs to mind, but I haven't looked out the datasheets to confirm suitability. Most op-amps nowadays have internal frequency compensation, so C4 could be redundant - probably anything better than a 741 is good enough.
     
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  4. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    I think that's a flag for unnecessary roughness.

    ak
     
  5. prashanthb

    Thread Starter Member

    May 17, 2015
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    Last edited: Aug 10, 2015
  6. absf

    Senior Member

    Dec 29, 2010
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    MJ4502 is available from Element 14 (or farnell). The price is not as high as I thought (USD 4.30).

    If you can get Japanese transistors locally, those with Ic=30A and Vceo>100V and Ptot>150W are as follows:

    2SB1232, 833, 694(25A)
    2SA 1043, 1044

    Most of the high current transistors are in the 2SD NPN category. If you can find one that uses NPN power transistors or better still power MOSFET. Then the component cost would be much less.

    Check their datasheet online and see if they are darlington pair and their casings suit your purpose. Some of them have internal diode on CE.

    Allen

    p/s: sorry, the PNP low frequency should be 2SBxxx. Let me check again.
     
    Last edited: Aug 11, 2015
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  7. ian field

    Distinguished Member

    Oct 27, 2012
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    AFAICR: All 2SA are PNP, most 2SB are PNP and all 2SC are NPN - I can't remember whether all 2SD are NPN.
     
  8. bertus

    Administrator

    Apr 5, 2008
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    Hello Ian,

    The 2sa,2sb are jis codes:

    SA: PNP HF transistor
    SB: PNP AF transistor
    SC: NPN HF transistor
    SD: NPN AF transistor
    SE: Diodes
    SF: Thyristors
    SG: Gunn devices
    SH: UJT
    SJ: P-channel FET
    SK: N-channel FET
    SM: Triac
    SQ: LED
    SR: Rectifier
    SS: Signal diodes
    ST: Avalanche diodes
    SV: Varicaps
    SZ: Zener diodes

    Here is the full text in the following link:
    http://www.elexp.com/t_tranmk.htm or
    http://www.gae.ucm.es/~padilla/extrawork/transistor.html

    Bertus
     
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  9. ian field

    Distinguished Member

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    Pretty sure that at one time or another I've encountered an NPN 2SB - but extremely rare.
     
  10. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    Yes that could be so.
    Exceptions prove the rule.

    Bertus
     
  11. ian field

    Distinguished Member

    Oct 27, 2012
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    Originally the designation was Japanese, but has since spread Asia-wide. There's bound to be the occasional aberration.

    When I made my living repairing VGA monitors, I encountered examples from pretty much every developed country - and some not so developed ones.

    Even with a heap of transistor equivalents books - sometimes I had to determine polarity by tracing the circuit, and just guess a suitable replacement.
     
  12. absf

    Senior Member

    Dec 29, 2010
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    There are a lot of old Samsung CRT monitors where people just throw them away. Some have 20" screen but most are 17". I savaged a lot of their PCB and found lots of C945 transistors inside. Some of the chips are TDAxxx and some made by Samsung.

    BTW are there any BDxxx or BUxxx transistors with Vceo>=100V, Ic=30A and Pc>=200W?

    Allen
     
  13. absf

    Senior Member

    Dec 29, 2010
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    I have lots of 2SB727 darlington power transistors from old OKI teleprinter machines. It has a 2SDxxx NPN matched pair too.

    Allen
     
  14. ian field

    Distinguished Member

    Oct 27, 2012
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    The European BU prefix transistors were high voltage types that you might find in a flyback SMPSU or horizontal output. Generally rated at least 1000V, but none anywhere the 200W you want.

    You might have to select something in a TO247 case for that kind of spec - Toshiba did a line of power transistors with 2 mounting holes that were a bit more hefty than the TO247 style parts, but I don't remember any more than they were 4 digit 2SC numbers.
     
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