Saw tooth wave generator using NE555

jacky February 1, 2012 8 Comments

Description.

A simple sawtooth wave generator circuit for generating a saw tooth wave form using a NE555 IC is given below. The frequency of the wave form can be varied by using a POT.

The capacitor C, resistor R and zener diode forms a constant current source for charging of the capacitor. When the voltage across capacitor reaches 2/3 Vcc the internal comparator inside 555 goes on and capacitor discharges. When the voltage across the capacitor goes below 1/3 Vcc the internal comparator goes off and now capacitor starts charging. As a result the capacitor will be switched between 2/3 Vcc and 1/3 Vcc, resulting in a sawtooth wave form across the capacitor. The diode make the output voltage to zero during the discharge phase.

Circuit diagram with Parts list.

saw-tooth-generator-circuit.gif

Notes. 

The frequency of the output voltage can be given by the equation,

f = (Vcc-2.7)/(R*C*Vpp).

Where Vcc is the supply voltage and Vpp is the peak voltage of the output required.

Comments
  • brainbox
    September 12, 2012

    POT means potentiometer.. More like a variable resistor

  • September 12, 2012

    Thankz, this ”article” really helped in my electronics exams…”EEC 244”.

  • March 16, 2010

    Is 555 timer used is astable or monostable

  • March 16, 2010

    what is POT??I don’t know what it means….

  • sami
    May 5, 2009

    The output voltage & current of the circuit is too low for my use. i need to amplify the output voltage & current of this circuit. is there any circuit diagram to amplify the output of the circuit?

    • admin
      May 5, 2009

      output voltage can be increased by increasing the supply voltage to 10 or 15V.
      If you need to amplify the output voltage you can use a simple transistor amplifier or an opamp.

  • Priya Singh
    February 24, 2009

    this circuit works well but i need to increase the discharge time..

  • Priya Singh
    February 24, 2009

    hi !!
    can u plz help me about how to increase the discharge time of the capacitor and make it bigger than the charging time?

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