I recently started working on a project to create a PIR sensor-based alarm system that plays a melody when someone enters the detection zone. This could serve as a friendly warning or alert, for example, at the front door of a house. The idea is to detect motion and trigger a melody to indicate someone's presence.
To achieve this, I needed a component capable of generating melodies. That’s when I discovered the UM66T Melody Generator IC, a small but versatile device that can produce pre-programmed tunes. The IC series offers a variety of melodies, each identified by a unique code. For instance, the UM66T19 chip generates the melody of Beethoven’s Für Elise.
Features of the UM66T Melody Generator IC
The UM66T doesn’t look like a typical integrated circuit; instead, it resembles a small transistor. It has only three pins:
- Vdd (Power Supply): Requires a 3V power source.
- Vss (Ground): The ground connection.
- Melody Output: Outputs the melody signal at 3V.
Inside the IC, there are components like an oscillator, a melody ROM, a tone generator, a tempo generator, and a beat generator, which all work together to produce melodies.
Testing the UM66T Melody Generator IC
To test the IC, I referred to the wiring schematic provided in the datasheet. The recommended circuit is simple, but it specifies the use of a 2SC9013 NPN transistor. Since this transistor wasn’t readily available to me, I tried using more common NPN transistors like the 2N3904 and 2N2222.
Observations:
- Both 2N3904 and 2N2222 transistors work with this IC.
- A lower base resistor value (1 kΩ instead of the recommended 4.7 kΩ) is needed to ensure proper operation.
- The 2N2222 transistor produces a louder sound than the 2N3904 because it can handle higher current.
Below is the modified circuit diagram I used:
Modified Wiring Diagram
Breadboard Implementation
I built the circuit on a breadboard as shown below:
Breadboard Setup
When I powered the circuit, the melody began to play. Hearing Für Elise from this tiny IC was quite satisfying!
Video Demonstration
Here’s a video demonstration of the UM66T Melody Generator IC in action:
Applications and Suggestions
This simple yet effective IC is perfect for adding melodies to small projects like alarms, doorbell systems, or decorative musical devices. If you have any questions or suggestions about this project, feel free to leave a comment below!
