This light for a pumpkin or Jack o'lantern operates on a single 9-volt battery and cycles through five colors—red, yellow, blue, green, and pink—changing every five seconds. It utilizes a 32,768 Hz crystal to achieve accurate timing. For my project, I am using a plastic Jack o'lantern purchased last year; the printed circuit board fits into the rear compartment where the original light was installed. Painting the interior of the Jack o'lantern white and positioning the LEDs toward the back yields optimal results. When installing in a real pumpkin, it is recommended to use a plastic container or cover the rear with electrical tape to protect the circuit board from moisture and residue inside the pumpkin.

The project is designed for flexibility and can accommodate LEDs of any color. The timing interval may be adjusted from 5 seconds to 0.5 seconds by removing the second integrated circuit (IC) chip, U2, and connecting pins 12 and 14 on the designated footprint for U2.

The KiCad files are uploaded as PumpkinLight.zip.

YouTube viedo https://youtu.be/NpbwNgSqOGg?si=Wl4RnKJxv1PeWnGr