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  1. #1
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    How this circuit works

    Hello ,

    Can some one help me understanding how this circuit functions? Basically the emitter terminal of T2 is used as a power supply in an application circuit.(I have shown like 12k ,as current requirement is low)

    Is this a darlington pair arrangement? R2 15k confuses me.. Can some one explain how it is working?

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    Sorry there has been a mistake .. both the supplies are 24V only no 48V in the system..forgive the mistake in figure..
    Last edited by ku637; 7th January 2019 at 16:34.

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  2. #2
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    Re: How this circuit works

    Yes, it is a Darlington arrangement. The additional resistor at T2 base is used sometimes to increase the speed of the transistor, in above case to decrease turn-off time.
    https://electronics.stackexchange.co...ton-transistor
    "Try SCE to AUX." /John Aaron/


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    Re: How this circuit works

    Is this a darlington pair arrangement?
    Yes.
    R2 15k confuses me..
    Why, base-emitter pull-down resistor is even built-in with many power darlington transistors, review datasheets. Its purpose is also reduction of leakage current.


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  4. #4
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    Re: How this circuit works

    Thank you for the input.. what can be the purpose of 47Ohms any suggestion? is it to limit the output drive current?



  5. #5
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    Re: How this circuit works

    Quote Originally Posted by ku637 View Post
    Thank you for the input.. what can be the purpose of 47Ohms any suggestion? is it to limit the output drive current?
    Yes. Probably the only purpose.
    "Try SCE to AUX." /John Aaron/


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