Linear voltage ramp, howto?

Discussion in 'General Electronics Chat' started by eimix, Sep 8, 2008.

  1. eimix

    Thread Starter Active Member

    Sep 2, 2008
    I have 555(NE555N to be exactly) timer controlled via 5 pin(control voltage, if NC it has 2/3 of Vcc)
    It is used for soft-start dc motor.

    Now it has 220uF cap connected, but it charges fast in beginning and slow at the end. ;) yes, yes i know that all cap's does the same.

    I need simple solution for slow charging in begining and fast at the end, or linear at least, is it possible without any chips?

    btw, i already know about simple small current source for linear charging, but i cannot fit in my circuit. it requires external supply line, i would like to use those 2/3 of Vcc that 5th pin has.

    Thanks for any comments ;)
  2. SgtWookie


    Jul 17, 2007
    See the attached ;)

    It's not going to get a great deal easier than that.
  3. eimix

    Thread Starter Active Member

    Sep 2, 2008
    thanks for suggestion.
    but seems too complex for me right now,
    i googled for such idea - but nothing simple is possible in my case :(
    after some more experience in building circuit i will try this one.

    thanks again