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Full wave square wave generator from dual led flasher.

Discussion in 'Electronic Basics' started by [email protected], Aug 21, 2005.

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  1. Guest

    I found this schematic of a dual led flasher in a
    book Could I eliminate the two led's and and
    connect the cathode of each to the anode of the other and get a full
    wave square wave output?
  2. ehsjr

    ehsjr Guest

    I don't know what you have in mind when you say "a full wave
    square wave".

    You'll get the square wave at the emitter of either of the
    transistors in the diagram at the site you mentioned.
    Don't change the circuit the way you mentioned
    For more information, see:

    You'll find the square wave diagram in figure 3.7.
    It will vary from 0 volts to Vcc

  3. Jasen Betts

    Jasen Betts Guest

    it's not the best circuit... it wastes 6 of the 9v running the oscilator.
    if you omit the LEDS (replace them with wire) you could get a square-ish wave
    that varies most of the way from 0 to 9v from the collector of either
    transistor (the junction of the 330 ohm resistor and 47uF capacitor

    I say square-ish because that type of oscilator tends to slowly relax towards
    the centre voltage before switching - probably why it's called a relaxation
    oscilator :)

    if you want to flash leds replace the 330 ohm resistors with 1K and put the
    LEDS in parallel with them and run the whole thing off 3V.
  4. ehsjr

    ehsjr Guest

    Astable multivibrator is more specific
    And kiss your leds goodbye.
  5. Jasen Betts

    Jasen Betts Guest

    there are other forms of astable multivibrator that rely on different
    mechanisms for the oscilation.
    never happened here. there's always some drop in the transistor...

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