IC555 Oscillator
================

IC555 is a very popular time circuit IC. It can be configured as an astable or monostable
multivibrator. The values of frequency and duty cycle are decided by two resistors and a capacitor. 


Objective
---------

Wire an astable multivibrator circuit using IC555, measure the frequency
and duty cycle of the output.

Procedure
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.. image:: schematics/ic555.svg
	   :width: 300px

-  Make connections
-  Set OD1 to high, for powering the circuit
-  measure frequency and duty cycle.
-  Repeat by changing the value of R1.


The output waveform is shown below. The frequency and dutycycle can be calculated using the equations given below
and compared with the measurements.

The durations of high and low voltage are: :math:`T_{1} = 0.693(R_{1} + R_{2})C` and :math:`T_{2} = 0.693 R_{2} C`.
Frequency :math:`f = \frac{1}{(T_{1}+T_{2})}` and duty cycle :math:`= \frac{T_{1}}{(T_{1}+T_{2})}`

.. image:: pics/ic555-screen.png
	   :width: 400px

Discussion
----------

The output waveform is shown in figure. Change the value of resistors or
the capacitor, and compare the frequency and duty cycle with the
calculated values. Variable resistors may be used to change the frequency and duty cycle.
