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Replacement for TIP125 Darlington

Discussion in 'Misc Electronics' started by Adriaan, Jul 25, 2004.

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  1. Adriaan

    Adriaan Guest

    Hi,

    I am trying to build an H-bridge. I got a diagram with two TIP125
    Darlington transistors and two TIP120's.

    I cannot get my hands on either of these components. What can I
    replace them with?

    Thanks,
    Adriaan
     
  2. CWatters

    CWatters Guest


    Farnell-in-one (a big distributor in the UK) has them but I don't know if
    they export and there might be a minimum order value?

    http://uk.farnell.com/

    ...try also cross ref database...

    http://www.ee.washington.edu/circuit_archive/parts/cross.html

    This says the TIP125=TIP126=TIP127
    which may not be helpful unless you look up the TIP127....

    TIP127 =
    2N6035 2SB673 TIP127
    2N6040 2N6041 2N6042
    2SB791 ECG262 2SB791
    ECG262 2SB791 ECG262

    Suggest you repeat this for the TIP120
     
  3. Because you're using these for a switch, a darlington is not the best
    choice. Darlingtons have a minimum V drop of a volt or so, which causes
    a lot of power to be wasted in the power transistors. You should use
    two separate transistors, with the collector of the first or driver
    tranaistor connectred to the supply, not to the collector of the second
    or output transistor. You then use a current limiting resistor from the
    emitter of the driver to the base of the output transistor.

    Another alternative is to use power MOSFETs which have very low on
    resistance. This allows a very high current with a minimum of
    heatsinking.
     
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