Sawtooth Wave Generator circuit using IC NE555


Waveform generator circuits are quite handy as we can employ those in several complex circuits as a feed to it. And square wave generator with IC 555 is very familiar and today we are going to see a circuit which employs IC 555 to generate sawtooth waveform. Sawtooth wave has several applications and its best known for its application in music. And before moving into the working of this circuit, you must understand the working of IC 555. Lets move into the working of this above Sawtooth generator circuit.


The whole working of this circuit is based on a simple charging discharging of the capacitor connected to the IC 555. The capacitor C, resistor R and zener diode forms a constant current for charging the capacitor C. When the capacitor gets charged it gradually reaches the 2/3 Vcc voltage across it and as a result the internal comparator inside 555 goes on and capacitor discharges. When the voltage drops below the 1/3 Vcc during discharging the internal comparator goes off and now capacitor starts charging again.

The capacitor is switched between 1/3 Vcc and 2/3 Vcc to make the generation of sawtooth waveform possible. As a result a sawtooth waveform will be generated due to the charging and discharging action of the Capacitor connected to the IC 555. The diode will make the output voltage zero during the discharge phase of the capacitor. The frequency of the waveform can be varied by using a POT in place of the R in the above circuit and the output frequency was given by the formula

F = (Vcc-2.7) / (R*C*Vpp)  

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