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  • LM555 output frequency drops when supply voltage from the regulator

    Wan Xi

    Member

    Updated: Oct 26, 2024
    Views: 1.2K
    Hi,

    I'm using a LM555 timer to produce a frequency of 240KHZ & 50% duty cycle.

    The circuit i'm using is Astable.
    RA is 82ohm
    RB is 200ohm
    C is 0.01uF
    RLs nothing

    I built up this circuit and got nearly 240K frequency and 44% duty cycle

    But when use a normal LM340T5 to produce a 5V to the LM555 timer...
    The frequency immediately drop to 190KHZ
    This cause my 3rd IC almost burn T^T

    anyone can guide me to the solution?

    Thanks
    Best Regards
    Wan Xi

    The LM555 Circuit which provide 240KHZ & 50% Duty Cycle:
    [​IMG]


    The regulator Circuit:
    [​IMG]
    0
    Replies
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Replies

  • sauravgoswami

    Member • Jan 8, 2009

    hey check your capacitor value,secondly somewere loading is goin on...
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  • ahmed_hassan133

    Member • Mar 5, 2009

    first,be sure that your de voltage is 5v purly after loading,and also check this link for mor information

    www.national.com/ds/LM/LM555.pdf
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