DIY haptic input knob: BLDC motor + round LCD
Why Hacker News recommends it
HN people hold it up as a polished solo hardware project and the go-to example of haptic knobs, including in discussions of physical car controls.
What it is
A two-minute demo of SmartKnob View, an open-source input knob built from a brushless gimbal motor, magnetic encoder and round LCD. Closed-loop torque control gives software-defined detents and end stops.
Recommended by 2 HN commenters across 2 different months, 2023 to 2026.
What Hacker News said
Strong rec laurencei · 2024-07 · on “Reverse-engineering my speakers' API to get reasonable volume control”
Hey OP - if your thinking about a smart knob with haptic feedback etc - check this open source project out that you can build yourself - its amazing: [LINK] Video demo here: [this video]
Recommends rzzzt · 2025-06 · on “Ask HN: What Are You Working On? (June 2025)”
Vaguely related - two encoder wheel projects on YouTube that might interest you: - "Wireless High Resolution Scrolling is Amazing": [LINK] - "DIY haptic input knob: BLDC motor + round LCD": [this video]
Cites ly3xqhl8g9 · 2023-05 · on “Where have all the hackers gone?”
Two answers: (i) late stage capitalism: who cares about going through a 400 pages spec sheet to try and reverse engineer the ludicrous Chinglish [1] in which all non-mainstream manuals are written today (wanted to declare war on China by myself when parsing through a Xinje PLC manual recently) when you could be fired at any time, a health emergency can bankrupt you, you generally feel more and more powerless, from your daily life to the once-in-a-lifetime-but-happening-every-week events such as economic crises, pandemics, wars, automated labor, x-flation, climate change, and so on and so forth. (ii) product refinement: we no longer are interested in a few lines of assembly which barely show
Cites scottbez1 · 2023-08 · on “Ask HN: What's the coolest physical thing you've made?”
I made a rotary input device that provides software-defined "virtual" detents and end-stops, implemented using a BLDC gimbal motor. It can dynamically switch from completely smooth unbounded rotation, to having detents with configurable spacing and strength and "end-stops" that spring back if you try to rotate past them. [this video] It's got a round LCD on the front of the knob (wired and supported via the hollow shaft of the motor) and uses the flex of the PCB and strain gauge sensors (in the latest revision, simply SMD resistors whose resistance changes when stretched) to detect when the knob is pressed down. It's open source hardware and software - [LINK] HN folks might appreciate that it com
Cites yonatan8070 · 2023-11 · on “Tesla Normal Operating Sounds”
This reminded me of the SmartKnob View I saw on YT a while back, it's a knob built on a burshless motor that's controlled to provide the user with software defined feedback like tactile clicks and end stops [this video]
Cites crote · 2026-05 · on “Mercedes-Benz commits to bringing back physical buttons”
I'm not convinced it is that easy. Cars traditionally have very generic button clusters, like [0]. It is even very common to have dummy buttons in there. Combine that with today's cars where those buttons are hooked up to some MCU to send a CAN message instead of being hardwired to a function-specific cable in a giant loom, and it is suddenly quite easy to change button functionality quite late in the design process for basically zero cost: you just need a slightly different label print and a small firmware patch! Or, if you want to be 100% flexible, go with the ATM approach where physical buttons are placed next to an icon shown on a screen[1]. All of the flexibility and all of the tactile