OpenSonora Alpha is one of the very first products born at Cantiere Barca laboratory while researching around a topic that we might call reuse electronics. It’s in fact a bluetooth amplified speaker made out of recovered materials: the wooden case is made of pallets, the woofers come from an old, broken boombox and the electronics components joining the two boards (amplifier and bluetooth modules) come from other old-fashioned PCBs laying around in my room.
While designing OpenSonora i was asking myselft: what can I really reuse or recover in electronics? I could reuse the old-school TDA2009 found in the boombox, a stereo class AB amplifier IC, but is it worth it? I mean, TDA200* family average efficienty lies around 40%. I’ll consume 10W to obtain maybe 4W as output power (stereo, so 2W for each channel). What if later i’d like to go for a battery update? How many batteries i’ll consume (of course rechargeable ones) to power up that vintage IC?
For these reasons OpenSonora Alpha adopts a high-efficiency, low-voltage class D amplifier module, with a typical efficiency of 80%, able to deliver 3W per channel at 5V. The low supply voltage required allowed me to use an old 5V power-supply from a 4 ports/10Mbps network HUB, which is nowadays almost useless, but a simple microUSB charger is even a possible solution. Then, all this stuff met a Bluetooth 2.1 stereo module, bought in one of the big online distributors, to make it wireless.
OpenSonora Alpha can be produced everywhere: a minimal laboratory with a soldering station is all what you need. You don’t need huge buildings, neither a specific location. It an entirely new, innovative and open product. Tomorrow someone could set-up a lab to produce a small serie elsewhere, downloading the plans (sources) from Github. Someone else could instead help me to correctly-design the PCB, because it may contain mistakes – i’ll not deny it, or add more functions. This is the collaborative dimension of an open project.
Yes, there are plenty of things we should improve yet. I’m not sure that de-soldering discrete components or etch the PCB using iron chloride make sense, when there are similar components that make the trick with just two RCA cables and no-frills. In a micro-scale production logic, maybe it’s just enough to recover wood, woofers and power supply unit. Even in an educational and inclusive logic it may be better, because it makes everything much easier.
We’ll see that. For now, when I come back home, all what I need to do is to turn on bluetooth on my phone and press play: it works!