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power on delay circuit

Discussion in 'Electronic Basics' started by chitta, Mar 6, 2008.

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  1. chitta

    chitta Guest

    Hi
    my name is chittaranjan.
    I need a waveform with power on as follows
    1.HIGH for 1 sec
    2. LOW for 2 sec
    3. HIGH permanently

    Please help me obtain this waveform without using any microcontroller
     
  2. Chris

    Chris Guest

    Read in fixed font or M$ Notepad:

    |
    | VCC
    | +
    | +|
    | ---
    | 1uF---
    | | |\ ___
    | .---o---|H>O--|<--|___|.
    | | | |/ 22K |
    | | .-. |
    | - | |1M |
    | ^ | | |
    | | '-' |
    | | | |
    | === === |
    | GND GND |
    | 3/6 74HC14 |
    | VCC VCC |
    | + + |
    | | | |
    | | .-. |
    | - | |3M |
    | ^ | | |
    | | '-' |
    | | | |\ ___ | |\
    | '---o--|H>O-->|--|___|-o--|H>O-
    | +| |/ 220K | |/
    | --- .-.
    | 1uF--- 2.2 M| |
    | | | |
    | === '-'
    | GND |
    | ===
    | GND
    (created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

    Requires 1/2 of a 74HC14 (or 74C14 if you're using a power supply of
    more than 6VDC), 2 1uF caps, 5 resistors and four 1N914 diodes. If
    your power supply takes more than 10ms. to charge up and discharge,
    you can lose the two protection diodes.

    Simple, not elegant or precise. Your timing on this may vary by quite
    a bit.

    Good luck
    Chris
     
  3. JeffM

    JeffM Guest

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