Speaker Frequency Generator

Introduction: Speaker Frequency Generator

In this lesson, we will be using the 555 timer to play sounds on a speaker. This project allows you to:

  • play many different frequencies on the speaker (with a potentiometer and a tuning capacitor)
  • change the volume of the speaker
  • have fun!


1x breadboard (at least half sized)

1x tuning capacitor

1x speaker

2x 10k potentiometer

1x N-channel MOSFET (can be replaced with a NPN BJT)

1x 555 timer IC

2x 1k resistor

1x 100nF capacitor

13x wires

1x 9V battery (with snap)

Step 1: Build It!🔧

follow the diagram above:

Step 2: Power⚡

Attach the battery and complete the circuit by connecting the ground rails together and the VCC rails together(but if you are confused by this, then just follow the diagram above)

Step 3: How to Use It and Troubleshooting

The potentiometer to the left is the volume control and the tuning capacitor and the potentiometer to the right controls the speaker's frequency.


If you do not have a MOSFET, you can use the diagram above to make the circuit with a NPN BJT and with one less resistor. If the project doesn't work, try the following:

  • check the wiring
  • check the battery
  • test your components, especially old ones
  • make sure all your components are attached properly on the breadboard
  • make sure your components can handle 9V or can operate at 9V

Step 4: How It Works

In a nutshell, the 555 timer creates a square wave with the discharging and charging of the tuning capacitor and it gets faster or slower as you turn the potentiometer to the right (frequency) and that signal gets fed into the transistor which rapidly connects and disconnects the speaker to ground. The potentiometer to the left allows you to resist current and voltage, thus allowing you to control the volume. The links below can help you understand this better:

How a 555 timer works

How a speaker works

How a transistor works

How a potentiometer works

How a tuning capacitor works

Be the First to Share


    • Anything Goes Contest

      Anything Goes Contest



    2 years ago

    Why are you using a mosfet in this circuit?


    Best Answer 2 years ago

    To be able to achieve high frequencies because MOSFETs have higher switching speeds than BJTs.