This circuit is a voltage-controlled oscillator
(VCO)  that uses the 555 timer IC as the main component. As expected, the 555 timer is  configured as an astable multivibrator to be able to serve as an oscillator. An astable multivibrator is  just a timing circuit whose output oscillates between 'low' and 'high'  continuously, in effect generating a train of pulses.
The difference of this circuit with the basic 555
astable circuit is that its 555's pin 5 is tied to an external voltage source.Pin 5 is the 555's control voltage pin, which allows the user to directly adjust  the threshold voltages to which the pin 2/pin 6 input voltages are compared by  the 555's internal comparators.  Since the outputs of these comparators control  the internal flip-flop that toggles the output of the 555,

  • What is the function pin2?
  • What happens if protect us from the input voltage?
adjusting the pin 5  control voltage also adjusts the frequency at which the 555 toggles its output.  Increasing the input voltage at pin 5decreases the output oscillation frequency  while decreasing the input voltage increases the output oscillation frequency.

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    We are Khaled Alanzi and Abdulrhman and we study in TTC riyadh and we specialization in electronics



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    December 2012
    November 2012