This project uses a Trinket M0 combined with the LiPo backpack, which will make this crown conveniently rechargeable. The diagram below is just to clearly illustrate the circuit connections and will not be the final layout -- the images for the final layout will be seen later.

And here are the circuit connections that need to be made between the components in a table format, in case it's useful:

LiPo backpack Trinket Neopixel Strip
BAT BAT 5V
GND GND GND
5V USB -
- 4 DIN

First, prepare the LiPo backpack. Cut the trace in between the two holes next to the JST port (next to the "5v" label). This will allow attaching a switch to turn the power on/off.

Next, prep some wires. Cut the following approximate lengths of ribbon cables, taking note of the number of wires that should be in each, strip and tin the exposed wires with some solder.

  • LiPo backpack to Trinket - 3 wires, 2.5"
  • LiPo backpack to switch - 2 wires, 3.5"
  • LED strip to Trinket - 3 wires, 7.25"

Now you can solder wires to the LiPo backpack.

Solder the 2-wire ribbon cable into the switch holes, and then solder the shorter 3-wire ribbon cable to the BAT, G and 5V holes. Make sure to cut any excess wires at the bottom of the backpack as flush as possible.

Tip: it'll be a little easier later on if you solder the striped wire into the BAT hole. 

Next, let's prep the LED strip. 

Cut a strip of 13 LEDs using a flush cutter, and take note of where the DI ("data in") end of the strip is. 

Tin the copper pads on the DI end of the strip, and solder the 3-wire ribbon cable wires on. 

Tip: it'll be a little easier later on if you solder the striped wire onto the 5V pad. 

At this point, you should now have the following prepared:

  • A LiPo backpack with two sets of wires
  • An LED strip with a set of wires on the DI end of the strip.
  • A Trinket M0 and a 400 mAh LiPo battery with nothing attached to each.

Now it's time to connect both the LED strip and the LiPo backpack to the Trinket M0.

With the help of a pair of needle nose pliers, and some patience, twist and solder together the tinned exposed wires for the following pairs:

  • LED strip's 5V wire and the Lipo backpack's BAT wire (both should be striped if you followed the tips in the previous steps above)
  • LED strip's GND wire and the LiPo backpack's G wire (both stand for "ground")

 

Solder the twisted wires together, and fit the combined wires into the Trinket M0's corresponding pins.

  • Combined ground wires into the Trinket's GND hole
  • Combined 5V/BAT wires into the Trinket's 5V hole

You may have to squeeze the combined soldered wires a bit to get it all to fit through.

Carefully take the LiPo backpack's 5V wire, route it through to the Trinket's USB hole, and solder.

Then take the remaining loose DI wire from the LED strip (the middle wire), and solder it into the hole labeled "4" on the Trinket.

Finally, you'll need to attach a switch to the remaining two wires on the LiPo backpack. 

Cut one of the legs on either side of the switch (leave the middle leg). Carefully cut the legs to about half of their original length and tin each leg with solder. 

Cut a few millimeters of heat shrink tubing and slide one onto each of the two wires from the LiPo backpack. Solder the two wires onto the two legs -- it doesn't matter which wire goes to which leg. Slide the tubing up and use the soldering iron to shrink it.

You should now have a completed circuit, and it should roughly look like the photo here! Take a moment to double check that the connections match the circuit diagram at the top of this page. A good way to check is to attach a battery to the LiPo backpack and flip the switch to see if any lights on the Trinket M0 turn on (the LED strip won't turn on yet).

Pause here, and marvel at your handywork so far. You're so close to creating a magical glowing crown! 

This guide was first published on Nov 10, 2021. It was last updated on 2021-11-10 13:47:15 -0500.

This page (Circuit Diagram and Assembly) was last updated on Nov 10, 2021.

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