This is another card made by the Circuit Scribe conductive pen, which can play a song and flash the LEDs. The circuit is based on the Attiny85 microcontroller to make the sound and control the LEDs. The microcontroller only has 5 useable pins, 1 for the buzzer (speaker) and 4 for the LEDs, so there are total of 12 LEDs which can be controlled with 4 pins using the Charlie-multiplexing method.
Circuit schematic
The circuit is plotted by the Silhouette Portrait and the SMD components can be soldered to the conductive trace. One 130 mAh Lipo battery is used to power the circuit, and is hidden under the “Happy birthday” piece together with the switch and the speaker.
And the finish birthday card:
…for my love!
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