Simple Adjustable Frequency Square Wave Generator Circuit

Simple Adjustable Frequency Square Wave Generator Circuit is easy and flexible.

It is used in signal processing, modulation and in many projects.

Here we see variable frequency oscillator using 555 timer IC which makes square waves and where user can change frequency.

555 works in astable mode and turning potentiometer changes output speed.

Circuit is good for making waveforms, clock pulses and for testing circuits.

It gives few Hz to many kHz and works with 5V to 15V power.

Circuit Working:

Parts List:

Circuit works in astable mode.

IC 555 keeps switching high and low by making square wave.

Frequency set by R1, VR1 and C1.

C2 keeps voltage stable.

Turn VR1 to change resistance, which changes 555 cycle time and frequency.

Formulas with Calculations:

Output frequency (f) and duty cycle (D) of 555 in astable mode:

Formulas:

f = 1.44 / ((R1 + 2VR1) × C)

T = 0.693 × (R1 + 2VR1) × C

T1 = 0.693 × (R1 + VR1) × C

T2 = 0.693 × VR1 × C

where:

• f is the frequency in Hz
• T is the time period
• T1 is the high time
• T2 is the low time
• R1 is 1kΩ resistor
• VR1 is 1MΩ potentiometer
• C1 is 0.01µF capacitor

How to Build:

To build a Simple Adjustable Frequency Square Wave Generator Circuit follow the below mentioned steps:

• Assemble parts like in circuit diagram:
• Pin 1 connected to GND
• Pin 2 connected to Pin 6
• Pin 3 connected to square wave output
• Pin 4 and Pin 8 connected to +5V to +15V supply
• Pin 5 connected to GND through C2
• R1 connected between +V and Pin 7
• VR1 connected between Pin 7 and Pins 2 and 6
• C1 connected between Pin 2 and GND

Conclusion:

Simple Adjustable Frequency Square Wave Generator Circuit is a useful project for beginners.

Turn potentiometer knob to change the speed.

It is good for function generator, PWM, clock pulses.

Circuit is easy to build with few parts and is good for beginners and experts.

References:

Effective way to generate low frequency square wave