First, place the components to make sure the pads line up.The recommended technique is to use solder paste in a fine-tipped syringe and a hotplate or toaster-oven. While it is possible to solder these puppies on with a traditional soldering iron and spool of solder, it's super hard and you might get pretty frustrated. Now that you've got a board, it's time to add the surface-mount LEDs and resistors. Using a bigger battery will increase the life of the necklace while keeping the LEDs bright but will require you to alter the clasp board to accommodate a different battery holder. For instance, using 150-ohm resistors would make the necklace last for nearly 3 hours, but keep in mind that the LEDs will be much dimmer too. If you want longer life out of your necklace, use bigger resistors or add a bigger battery. Thankfully these batteries are pretty cheap! Unfortunately, with a CR1025 battery, this necklace will only last for about an hour. Therefore, the whole necklace draws about 40mA. This necklace uses 43-ohm resistors, so with a voltage drop of ~2.5 volts across the LEDs and a 3-volt battery, that breaks down to ~10mA drawn from each LED. Then we laid out the traces on the board (shown here) and added large pads on the head and wingtip to attach the mounting hardware for the chain/cord that will eventually complete the necklace and the circuit. For a more detailed description of parallel and series circuits, check out this page.
HUMMINGBIRD NECKLACE FULL
This allowed for each LED to have the full 3-volt drop across it, and it also means that the other LEDs keep working if one burns out. To make our file, we made a simple schematic of 4 surface-mount (SMD) resistors and LEDs in parallel rather than in series. That board file is attached, though, so you don't have to!
HUMMINGBIRD NECKLACE HOW TO
If you don't know how to use EAGLE or need a refresher, check out our tutorial on designing circuits with EAGLE.ĮAGLE makes it hard to trace or replicate outlines from images, so we ended up freehanding the humming bird outline. We've provided design files for you to use, but of course you could also design your own! You could start by finding an image to use as concept art, like the hummingbird picture from this site, and then head over to EAGLE.
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