Square and Triangle Wave Generator Circuit

This Square and Triangle Wave Generator Circuit is a simple waveform generator.

It gives two outputs at same time with one output is square wave and another output is triangle wave.

Also, the circuit uses only one IC which uses few resistors and capacitors.

So the cost is low and the circuit is easy to build.

Moreover, it works on low voltage supply, so it is useful for students and hobby users.

Therefore, this circuit is good for learning signal generation basics.

Square and Triangle Wave Output Graph:

The graph shows two waveforms from the circuit.

Top graph is square wave output.

Voltage goes high and low suddenly and this output comes from IC output pin.

Bottom graph is triangle wave output.

Voltage goes up slowly and goes down slowly and this comes from capacitor charge and discharge.

Both waveforms repeat again and again and they show how signal looks at the output.

So, the circuit gives square and triangle wave together.

Circuit Working:

Parts List:

At start the power is given to the circuit where the supply can be 3V to 15V.

Then op amp IC starts working and it compares voltage on its inputs.

Capacitor C1 starts charging through resistors.

When voltage reaches a limit then output changes.

So output goes high or low and this makes square wave at IC pin 2.

Next, square wave goes to transistor Q1 and then this transistor works as emitter follower.

Capacitor C2 charges and discharges slowly and the voltage goes up and down linearly.

So triangle wave is formed.

VR1 controls charging speed, so frequency changes smoothly.

Finally, square and triangle waves come together.

Formula with Calculation:

Frequency mainly depends on R1, VR1 and C1.

General frequency formula:

Frequency = 1 divided by (2 x R x C)

where,

• R is the total resistance (R1 + VR1 value used)
• C is the C1 capacitor value

Calculation as in circuit diagram:

Let say R1 is 10 kilo ohm
Let VR1 set to 50 kilo ohm
Total R is 60 kilo ohm
Let say C1 is 0.47 micro farad

Frequency = 1 divided by (2 x 60000 x 0.00000047)

Frequency = approximately 17.7 Hz

By changing VR1 value frequency can be increased or decreased.

How to Build:

To build a Square and Triangle Wave Generator Circuit following steps are required to follow:

• First, collect all parts as per circuit diagram.
• Then start with op amp IC1 pin 1 input pin is connected to VR1, switch side, Q1 base and C2 network.
• IC1 pin 2 is output pin and square wave output is taken from here.
• IC1 pin 7 is Vss pin is connected to circuit ground.
• IC1 pin 14 is Vdd pin is connected to 3V to 15V positive supply.
• Transistor Q1 collector is connected to positive supply.
• Q1 base is connected between VR1 and C2.
• Q1 emitter is connected to ground through resistor R2.
• Triangle waveform is connected between emitter of Q1 and resistor R2
• Capacitor C1 one side is connected to switch and other side is connected to ground.

Conclusion:

This Square and Triangle Wave Generator Circuit is a simple project.

It gives square wave and triangle wave at same time.

Also, it uses very few parts so the circuit is easy to make.

Moreover, frequency change is smooth and power use is also very low.

Therefore, this circuit is good for beginners.

References:

Datasheet IC CD 40106