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q:for the masters of electronics of the web a problem with ne555

Discussion in 'Electronic Design' started by [email protected], Mar 23, 2005.

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  1. Guest

    hi
    I have a problem with ne555 I connect the ne555 in astable mode with
    (vcc=5volt) I connect pin 2,6&7 together with 2Mohm
    variable resistance & cap 220uf to get the maximum required time
    (~150sec)but when I shorted the variable leads to get the minimum
    required time ( ~.001 sec or less if it possible) I connect 1 ohm
    resistor series with the variable to catch my goal but ne555 is
    freezing with high level output
    my goal: when I short the variable leads ne555 give my as small as
    possible pulse ( pulse width .001 sec or less )

    thank you for helps
    yar
     
  2. Ban

    Ban Guest

    It doesn't need a master to understand a 555, ask John Fields, but don't
    mess with Texas.
    I would suggest you read the datasheet first
    http://www.fairchildsemi.com/ds/NE/NE555.pdf
    have a look at figure6 where you find a minimum value of 1k. You will have
    to switch in different capacitors for shorter times. you can automatize
    switching with transistors (BJT or FET). Only this way you can resolve those
    short times on your pot anyway.
     
  3. On Thu, 24 Mar 2005 06:12:16 GMT, in sci.electronics.design "Ban"
    Texas or Texas Instruments?

    I would have thought that TI could make a descent 555 by now


    martin


    Opinions are like assholes -- everyone has one
     
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