I recently discovered an online simulation platform and successfully implemented a simple running light project.

[moonlight0114]

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To replicate this project, you'll need:

• Several LEDs
• Resistors to limit current flow through the LEDs
• A switch to initiate the project

Component Selection:

I chose four yellow LEDs with a forward voltage of 2.4V and a maximum current of 0.03A. To ensure the current stays below 0.03A, a resistor value greater than 86Ω is required. I opted for a 100Ω resistor (R2).

Circuit Operation:

When the switch is closed, the Arduino UNO detects a high-level input on pin A0. This triggers the running light sequence. If the switch is opened mid-cycle, the LEDs will turn off upon cycle completion.

Project gallery：https://www.pcbx.com/sim/?id=24f475321cdf4d3ab00eccc18052e3fc