Christmas Lighted Decoration Battery Eliminator

Every year we hang our lighted Christmas reef on the door and insert a new set of D sized batteries and at the end of the holidays, we toss the batteries and store the reef for the next year. I have some spare LM2596 step down buck converters, so this year, no more batteries, instead using a USB charger as the power source, I made a versatile housing for the buck converter with the convenience of a standard plug on the output to energize any low powered Christmas lighting features.

All parts were printed with PLA, 0.4mm nozzle, 0.2mm layer height, 15% Grid infill, and 3 perimeters. In addition to the printed parts, you will need:

1. LM2596 step down Buck Converter
2. USB cable - normally old cables get ruined at the phone end and no longer work, which is great to re-purpose for this project. I used a 10 foot wrecked cable.
3. Two (2) M2x5  and two (2) M2x8 flat head screws
4. Clear filament, 20mm length, used to direct the onboard LED to the cover.
5. #50 drill bit, used to enlarge clear filament hole
6. 3-position single row 2.54mm pitch male and female Dupont wire connectors (you can salvage these parts with wire attached from an old computer box).
7. Solder iron and solder
8. Glue, wire
9. Multimeter and misc. tools

Some assembly notes:

• Give yourself some length of wire to work with when soldering to the buck converter
• The Dupont connector is glued in place
• For best lighting results, the clear filament should be roll cut with a knife to ensure a clean end interface for the LED light to shine through
• The threaded end holes may need to be enlarged with a drill bit if it becomes too hard to fully turn in the screws
• Buck Converters typically have a max current of 3A, so ensure your power load does not exceed this and the USB charger is capable of delivering that amount of current
• Dial in the output to the desired voltage measured with a multimeter. For 2 alkaline batteries in series, the output should be 3V to 3.2V