This $30 iPad stylus senses pressure via headphone jack
Stylus manufacturers have been working hard to replicate the sensation of writing and sketching on tablets over the years, hence the handful of styli that support pressure sensing and palm rejection these days. Unfortunately, these pens don't come cheap, with the Apple Pencil asking for $99 but is still only compatible with the iPad Pro series. Even the other good styli with greater iPad compatibility start at around $50. However, Hong Kong-based GreenBulb has come up with a cunning solution dubbed SonarPen that only costs $30, yet it supports both pressure sensing and palm rejection by making use of the headphone jack. No charging nor wireless connectivity required here, just plug it in and sketch away. Here's how the SonarPen works: as the name suggests, it relies on audio signal to relay touch and pressure data back to the tablet. And since there is also touch input on the touchscreen itself, the SonarPen supports palm rejection by matching signals from both sides. The ...