Sawtooth generator circuit

Posted on Jan 29, 2013

Sawtooth wave generators using opamp are very common. But the disadvantage is that it requires a bipolar power supply. A sawtooth wave generator can be built using a simple 555 timer IC and a transistor as shown in the circuit diagram. The working of the circuit can be explained as follows: The part of the circuit consisting of the capacitor C, transistor,zener diode and the resistors form a constant current source to charge the capacitor. Initially assume the capacitor is fully discharged. The voltage across it is zero and hence the internal comparators inside the 555 connected to pin 2 causes the 555's output to go high and the internal transistor of 555 shorting the capacitor C to ground opens and the capacitor starts charging to the supply voltage.

Click here to download the full size of the above Circuit.

As it charges, when its voltage increases above 2/3rd the supply voltage, the 555's output goes low, and shorts the C to ground, thus discharging it. Again the 555's output goes high when the voltage across C decreases below 1/3rd supply. Hence the capacitor charges and discharges between 2/3rd and 1/3rd supply. Note that the output is taken across the capacitor. The 1N4001 diode makes the voltage across the capacitor go to ground level (almost). The frequency of the circuit is given by: f = (Vcc-2.7)/(R*C*Vpp) where: Vcc= Supply voltage. Vpp= Peak to peak voltage of the output required. Choose proper R,C,Vpp and Vcc values to get the required 'f' value.

Visit page

Leave Comment

characters left:

Related Circuits

Discrete-sequence-oscillator

The swept-frequency oscillator offers an inexpensive source of discrete frequencies for use in testing digital circuits. In this configuration, the circuit generates an 80-second seguence of eight...

Variable-duty-cycle-oscillator

In a basic astable timer, configuration timing periods 11 and 12 are not controlled independently. The lack of control makes it difficult to maintain a constant period, T, if either 11 or 12 is...

Rlc-oscillator

A positive transient, such as the power switch closing, charges r through L to a voltage above the supply voltage, if Q is sufficient. When the current reverses, the diode blocks and triggers...

Hc-based-oscillators

Two inverters, one resistor, and one capacitor are all that is required to make a HC(T)-based oscillator that gives reliable operation up to about 10 MHz. The use of two HC inverters produces a...

Hcu-hct-based-oscillator

When frequency stability is not of prime importance, a simple, yet reliable, digital clock oscillator can be made with the aid of relatively few components. High-speed CMOS (HCU/HCf) inverters or...

Low-frequency-oscillator

This simple rc oscillator uses a medium-speed comparator with hysteresis and feedback through Rl and Cl as timing elements. The frequency of oscillation is, at least theoretically, independent from...

Xor-gate-oscillator

An exclusive-OR gate, IClD, turns a simple CMOS oscillator into an FSK generator. When the data input increases, IClD inverts, and negative feedback through R2 lowers the circuit"s output...

Cmos-oscillator

The common clock oscillator in Fig. 68-19A has two small problems: It might not, in fact, oscillate if the transition regions of its two gates differ. If it does oscillate, it might sometimes...

New Circuits

Zero consumption Anti-theft High power Code Switch for E-Bike Batteries

This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
Ultrasonic distance finder circuit

The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Simple Metal detector circuit with CD4030

Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Fully automatic watering circuit for flower pots

Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
Simple deep searching metal detector circuit

The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
Sub-Harmonic Bass Converter for Electric Guitars

The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
Echo Depth Sounding Sonar for Boats

In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
100W HiFi Audio Amplifier Circuit

This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
Plant-Pot Water Level Indicator Circuit

A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....

Create NOW your QR MENU for your Restaurant / Hotel / Bar / Caffe,

Comprehensive ordering/paying features. fully personalized to suit your Business.

Update Anytime! Easy and Simple!

Popular Circuits

StunGun circuit

The Electronic Dazer is a modern, portable, personal-protection appliance. It generates hight...

Acceleration sensing USB interface

The TiltStick is a small acceleration sensing device in form of a USB stick. It's using a two...

Mosfet Buffer Amplifier Circuit

A MOSFET is used as a wideband buffer amplifier. T1 is wound on a toroid of approximately /f...

Closed-Loop Peak Detector Circuit

This closed-loop peak detector circuit uses a Schottky diode inside feedback loop to obtain good...

Electrical transformer tutorial

Afroman covers the basics of how transformers work, where to shop for step down mains...

Three-State Continuity Tester

The continuity tester can distinguish between high-, medium-, and low-resistance connections....

Delay circuit of a multi-level output

As shown having a multi-stage delay circuit is output. The operational amplifier circuit used as...

Power Audio Amplifier DMOS 2x100W using two TDA2794

The TDA 7294 of T-MICROELECTRONICS is a monolithic integrated circuit in a "Multiwatt 15" shell...