.. 3.5

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

**Objective**

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

.. image:: schematics/osc555.svg
	   :width: 300px
.. image:: pics/ic555-screen.png
	   :width: 300px

Circuit is shown in figure. The frequency is given by
:math:`f = 1 /(\ln 2 \times C \times (R_1 + 2 R_2)`. The HIGH time is given by
:math:`\ln 2 \times C \times (R_1 + R_2)` and LOW time by
:math:`\ln 2 \times C \times R_2`.

**Procedure**

-  Make connections
-  measure frequency and duty cycle.
-  Repeat by changing the value of R1

**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.
