This Square and Triangle Wave Generator Circuit is a simple waveform generator, which 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 and 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, here, the voltage goes high and low suddenly and this output comes from IC output pin.
Bottom graph is triangle wave output and here, the 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:
| Components | Values | Quantity |
|---|---|---|
| Resistors | 10k, 4.7k 1/4 watts | 1 each |
| Potentiometer 100k | 1 | |
| Capacitors | Ceramic 0.47µF, 0.0047µF | 1 each |
| Semiconductors | IC CD 40106 Hex Schmitt Trigger | 1 |
| Transistor BC547 NPN | 1 | |
| SPDT Slide Switch | 1 | |
| Power Supply 3V to 15V DC | 1 |
At the start, the circuit receives a 3 V to 15 V power supply, the op-amp IC then starts operating and compares the voltages at its input terminals.
Then capacitor C1 starts charging through resistors and when voltage reaches a limit then output changes; so output goes high or low and this makes square wave at IC pin 2.
Next, the square wave drives transistor Q1, which operates as an emitter follower, then capacitor C2 charges and discharges slowly, causing the voltage to rise and fall gradually, as a result, the circuit generates a triangle wave.
Finally, VR1 controls charging speed, so frequency changes smoothly and then 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 the total resistance (R1 + VR1 value used)
- C is the C1 capacitor value
Calculation as in circuit diagram:
R1 is 10 kilo ohm
Assume VR1 set to 50 kilo ohm
Total R is 60 kilo ohm
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 increase or decrease.
How to Build:
To build a Square and Triangle Wave Generator Circuit follow below steps for connection:
- First, collect all parts as per circuit diagram.
- Then start with op amp IC1 pin 1 input pin connected to VR1, switch side, Q1 base and C2 network.
- After that, IC1 pin 2 output pin and square wave output taken from here.
- IC1 pin 7 Vss pin connected to circuit ground.
- IC1 pin 14 Vdd pin connected to 3V to 15V positive supply.
- Now transistor Q1 collector connected to positive supply, Q1 base connected between VR1 and C2 and then Q1 emitter connected to ground through resistor R2.
- Also, triangle waveform connected between emitter of Q1 and resistor R2
- Lastly, capacitor C1 one side connected to switch and other side connected to ground.
Conclusion:
To conclude, this Square and Triangle Wave Generator Circuit is a simple project, as 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 and therefore, this circuit is good for beginners.
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