Star Twister

1 Jan 2023

This is a Hack The Holidays project to make some interesting electronic ornaments.

This year I really wanted to finish before Christmas, so the ornaments could actually be used to contribute to the festive season.

Here is a video that shows the ornaments and how they were made:

A key objective of the project was to make these ornaments super simple to operate because they may be used by anyone of any age.
So basically they just have an on/off switch.
Of course they need to be colorful so RGB LEDs are incorporated.
To add variety, 2 different PCBs were designed.
To make the visual impact more dynamic, the LEDs need to flash different colors randomly.
To convert a standard PCB into different ornamental shapes, different bodies were 3D printed.
To go over the top and add animation, one PCB version includes a motor, that keeps the ornament twisting randomly.

Flashing Bauble PCB

Here is the random color flashing schematic:

Flashing Bauble 9 LED PCB:

Star Twister

Here is the Star Twister schematic - to create random rotary oscillation and random color flashing:

Note the connector for either an external switch or external power.

Start Twister PCB:

The motor is driven by an H-bridge which periodically pulses the motor and alternates the polarity of the pulse each time.
The period of the pulses can be adjusted by jumper selection of counter outputs or by RC oscillator time constant adjustment.
The duration of the pulses can be adjusted by adjusting the time constants of the 2 inverter delay circuits.

When the motor starts, the it creates torque between the armature and the stator which tends to make the armature and the stator spin in opposite directions. The stator is connected to the PCB while the armature is connected to the string. The inertia of the armature and the PCB ensure both armature and stator will spin in opposite directions. The torsion in the string is minimal, so it will tend to wind up. When the motor is off the wound up torsion in the string will tend to reverse its spin which increases the spin of the PCB. The momentum of the PCB will continue spinning until the string winds up in the other direction and eventually reverses the spin of the PCB. The timing of motor activations can be set up to allow time for one or more oscillating spin cycles from string windup to play out between motor activations.

Assembled Baubles:

Animated Baubles on a tree:

Conclusions

This was a fun project that was completed in time for my Christmas deadline. It takes LED ornaments to the next level, not only using multiple colors and multiple shapes, and not only making them randomly change color and randomly flash but also making them physically spin semi randomly. All this action is accomplished keeping costs down and meeting the requirement to have ultra simple user controls, just on/off slide switches. Designing 2 PCBs kept the build clean and attractive while allowing any shape to be implemented with 3D design of the outer shell. These PCBs can be used to light up or animate any the 3D designed shapes and I have 10 of each PCB so it is only a matter of deciding what future ornaments will look like. I'm toying with the idea of iconizing some of my build projects (making the shell shapes look like recognizable icons). It is always satisfying to create something that brings a little joy to people's lives.

Links:

/challenges-projects/project14/hacktheholidays?ICID=P14main

Project14 | Winners Announcement: Hack the Holidays!