Light Up Bracelet – Dead-bug style

Who doesn’t like blinking LED’s – especially when you link them to some sensory input such as Sound, for example. My maker friend Sohil Patel dished out a sound activated LED bracelet in time for Navratri, our nine day festival of Dance. He put up an instructable showing how he used a couple of simple parts to rig it all up – read about it here :

I thought it was something Samata would enjoy since she loves to dance, particularly during Navratri. Sohil’s diagram didn’t look alright – the LED anodes and the [+] of the battery are shown conected to GND, and when Q2 turns On, the LED’s get connected to GND on both sides (anode and cathode). Just the excuse I needed to crank up my favourite EDA program – KiCad – and churn out a corrected circuit.

schematic of sound activated LED Bracelet

But why would I want to make a PCB for a circuit that uses just a handful of parts. No Sir, I decided to ditch using any kind of PCB, and make it “Dead-bug” style. Dead-bugging is an art by itself. See below some examples of functional and non-functional deadbug sculptures.

I soldered all the parts (2 transistors, 1 resistor, 1 trimpot, and the Mic) directly to each other, and then carefully wrapped the whole thing is a bit of kapton tape I had lying around (there’s only so much you can use for a 3D printer heated bed). I fashioned the eight 10mm blue LED’s in a long, parallel chain and hooked them to the “dead-bug” with short lengths of flex wire. Sohil originally used coin cells for his bracelet, but I had none lying around. Digging in to my part’s box, I came up with a LiPo cell rated for 8 Wh – enough to last a really long time. Here’s a video of the braclet on my ugly arms. [NOTE : Although I added a 10nF capacitor at the base of Q1 in the schematic, I didn’t finally use it in order to use one less part].

Deadbugging can be fun, and with some patience, you can create really nice, functional circuits or electronic art too.