UNTRANSLATED .. 3.5

IC555 Oscillator

Objective

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

_images/osc555.svg _images/ic555-screen.png

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