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Two Transistor Metronome
Two-Transistor Metronome Circuit
Created on: 2013-05-10
Updated on: 2025-02-16
An easy-to-build DIY two-transistor metronome circuit that gives a periodic tick sound. The frequency of the tick can be adjusted using a potentiometer. An easy-to-build circuit for beginners in electronics.
What is a Metronome?
A metronome is a device that produces a consistent ticking sound, which helps musicians maintain a steady rhythm while practicing. Traditional mechanical metronomes use a swinging pendulum, but electronic metronomes like this two-transistor circuit offer a simple and affordable alternative. This project is ideal for electronics beginners and hobbyists who want to learn about transistor-based oscillators and audio circuits. It's fun to build and operate, even if you're not a musician!
Transistor Metronome Demonstration Video
The following video shows the metronome operating and the tick speed being adjusted using the potentiometer.
Two-Transistor Metronome Circuit Diagram
The two-transistor metronome circuit shown here can be powered by a 9V battery.
The frequency of the tick is changed using potentiometer RV1. The lower the resistance set on the potentiometer, the faster the metronome will tick.
Resistor R1 is used to set the maximum speed that the metronome will tick at. Adjust R1 and RV1 to modify the speed or frequency range of the metronome.
Parts List
The following list contains the parts or components for the transistor metronome circuit:
| Component | Value | Description |
|---|---|---|
| Q1 | PN2222 | NPN transistor |
| Q2 | PN2907 | PNP transistor |
| R1 | 10k | 10 kΩ resistor, 1/4W, 5% or better |
| R2 | 2k2 | 2.2 kΩ resistor, 1/4W, 5% or better |
| R3 | 2k2 | 2.2 kΩ resistor, 1/4W, 5% or better |
| RV1 | 22k | 22 kΩ potentiometer |
| SP1 | 8 Ω | 8-ohm loudspeaker |
| Vcc | 9V | 9V battery and battery clip |
| C1 | 100µF | 100 µF electrolytic capacitor |
Assembling the Metronome Circuit on Breadboard
In order to plug the speaker and battery clip into the electronic breadboard, they may need to have wires soldered to them. The links in the following section describe how to solder wire to these components.
Loudspeaker and Battery Clip
The speaker, potentiometer, and battery clip have single core wire soldered to them to make them easy to plug into the breadboard.
See the related articles on how to solder wires to these two devices:
Preparing the Potentiometer
Use the same soldering techniques described in the above articles to add wires to the potentiometer if needed. It may be possible to avoid soldering wires to the potentiometer if the potentiometer has pins instead of solder lugs. If it has pins, then it may be possible to plug male-to-female Dupont wires onto the pins, so that the potentiometer can be plugged into the breadboard.
Steps to Build the Two-Transistor Metronome Circuit on a Breadboard
- Gather components: two transistors, resistors, a capacitor, and a potentiometer.
- Get some jumper wires ready for making connections between components.
- Assemble the circuit on a breadboard as shown in the diagram.
- Use the power rails of the breadboard for the 9V and 0V (or GND) connection points of the circuit.
- Connect the loudspeaker to the circuit, as shown in the circuit diagram.
- Connect the battery clip to the power rails of the breadboard, so that the battery will power the circuit as shown.
- Connect a 9V battery to the battery clip and adjust the potentiometer to change the ticking speed.
Related Easy DIY Circuits for Beginners
If you enjoyed building this metronome, check out these other beginner-friendly projects: