An Open Source Linear Capacitive Encoder
If you’ve ever pulled aside a set of digital calipers, you’ve in all probability marvelled on the capacitive encoder that does all of the measuring work. There’s nothing stopping you from utilizing the identical strategies your self, as [Nick] demonstrates with an open-source capacitive encoder of his own design.
The sensor PCB works by by having a grid of eight transmitting antennas, etched right into a PCB, beneath a bigger receiving antenna. The transmitting antennas pulse out a sample because the sensor PCB strikes, with the indicators bouncing again from the reflector PCB which is fastened in place. The various capacitance attributable to the place of the reflector components relative to the sensor PCB varies the power of the pulses hitting the receiving antenna. A microcontroller—on this case an STM32—can learn these pulses to find out the displacement of the sensor PCB relative to the reflector all the way down to a really positive diploma. In this case, to an accuracy of 40 micrometers. Not dangerous!
If you want ultra-fine linear monitoring for one thing you’re constructing, you would possibly discover this undertaking very helpful. Files can be found on Github for the curious, together with a terrific explainer on precisely how the capacitive coupling turns into a positional studying. You may research earlier teardowns we’ve featured on cheap digital calipers, simply to spherical out your training additional. If you’re working by yourself spectacular workshop tools, or subcomponents of such issues therein, don’t hesitate to tell us on the tipsline!
