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Saw tooth wave generator using NE555

2016-04-30 10:13  
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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.