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Circuit design for a novice

  1. Dec 18, 2005 #1
    I want to try and build an LED clock.

    The idea is to have a sequence of LED`s that light up one at a time at a regular time period over a pre-definied time. Once the all the LED's are on then they start to go off one at a time.

    I thought I'd just try and get 5 LED's to light up one at at time first.

    My problem is i have never designed any form of circuit.

    I know how LED's , capasitors, resistors and inductors etc. work, but to try and integrate these components into something useful is beyond my current understanding so I'm asking for a little guidence.

    HOw do you get a sequence of LED`s to light up one at a time?
  2. jcsd
  3. Dec 18, 2005 #2


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    To understand what you would like to design, I recommend reading up on digital electronics (especially timing circuits) One approach can utilize the following: stable reference oscillator (based on a quartz crystal) and timing elements - flipflops (work with binary inputs inputs and outputs) arranged & wired in a sequence such that the final output (binary 1 or 0) occurs once per "interval of time". The time interval can be whatever you design it (20sec, 10min, 39min, 17hrs, 40yrs etc..) When the output toggles, you can feed that signal to an output driver to light up an LED. To have successive LEDs light up after each interval, you could add some additional control logic (digital elements) that will select which LED to light up or shut off.

    If this looks more than you are ready to tackle just now, you could look at some hobby clock circuits. Here is an example of a clock based in a 555 timer IC.
    Last edited: Dec 18, 2005
  4. Dec 18, 2005 #3


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    Check out counters and timers.
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