Typically, when we want to build something with a DC motor, we might grab a bunch of AAs, or a single lithium cell at the very least. Electric toothbrushes often run on more humble power sources, like a single NiMH battery. They’re designed to get useful motion out of just 1.2V, and [Marian Hryntsiv] has taken a look at what makes them tick.
The article focuses on an electric toothbrush built around the Low Voltage GreenPAK SLG47513 chip. It’s designed to work at voltages from just 1 to 1.65 V. To make the most of the limited power available, the toothbrush stays in sleep mode most of the time when it’s not working in oral health.
[Marian] steps through the various parts of the circuit, and also explains the unique functionality baked into the brush. Of particular interest are the timer routines that guide the user through brushing each section of the mouth in turn, before a notification that tells them that 2 minutes of brushing time has elapsed. There’s also a useful explanation of the inductive charging method used.
Electric toothbrushes may be mundane home items today, but they’re an example of a product that has largely already been optimized to the nth degree. Until laser-based plaque removal or enamel regeneration technology gets off the ground, this is as good as it gets. We can dream, though!
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