This project is my 555-based attempt to add some electronic flair to my Christmas tree. We didn't have many ornaments when we got our first tree last year so I opened KiCAD and designed a simple one. This is a simple circular PCB with a 150 mil hole to place a hook through. The front has a fun silkscreen design with a snowman and some trees (and an error! CR2023 cells don't exist!), along with some red SMD LEDs that blink when the device is turned on. The back contains all the magic: a TLC555 configured as an astable oscillator, it's associated passives, a CR2032 battery holder, and a switch to turn the device off.

I gave some out to friends and they were a hit! Battery life is quite good from what I hear. I incorporated a lot of feedback into 2024's ornament, which includes new improvements and features.

According to Digi-Key's 555 calculator, the selected passives (R1=R2=200K, C1 = 10u) result in a 0.24 Hz oscillation with a 66.7% duty cycle.