There’s no doubting the wonders that micro-electromechanical systems (MEMS) technology have brought to the world. With MEMS chips, your phone can detect the slightest movement, turning it into a sensitive sensor platform that can almost anticipate what you’re going to do next. Actually, it’s kind of creepy when you think about it.
But before nano-scale MEMS inertial sensing came along, lots of products needed to know their ups from their downs, and many turned to products such as this vibrating piezoelectric gyroscope that [Kerry Wong] found in an old camcorder. The video below shows a teardown of the sensor, huge by MEMS standards but still a marvel of micro-engineering. The device is classified as a Coriolis vibratory gyroscope (CVG) which, as the name implies, uses the Coriolis effect to sense rotation. In this device, [Kerry] found that a long, narrow piezoelectric element spans the long axis of the sensor, suspended from what appears to be four flexible arms. [Kerry] probed the innards of the sensor while powered up and discovered a 22 kHz signal on the piezo element; this vibrates the bar in one plane so that when it rotates, it exerts a force on the support arms that can be detected. Indeed, [Kerry] hooked the output of the sensor to a wonderfully old-school VOM whose needle wiggled with the slightest movement of the sensor.
Sadly, MEMS made this kind of sensor obsolete, but we appreciate the look under the hood. And really, MEMS chips are using the same principle to detect motion, just on a much smaller scale. Want the MEMS basics? [Al] has you covered.
Continue reading “Piezoelectric Gyro Shows How They Rolled Back in the Day”
When we first saw [Mikeasaurus’] project to rotate his TV 90 degrees in case he wanted to lay down and channel surf we were ready to be unimpressed. But it grew on us as we read about how he fabricated his own gearing system to make a car seat motor rotate the TV.
The gearing system is made from plywood and the design was from geargenerator.com, a freebie design tool we’ve covered before. You’d think you’d need a laser cutter, but in this case, the gear forms were printed out, glued on the plywood and then cut out manually. Each gear is made of several laminated together.
Continue reading “Couch Potato Refined: Self-Rotating TV Uses Plywood Gears”
[Mal’oo] has one of those laptop computers whose screen swivels to turn it into a tablet. But the thing is a few years old and didn’t come with an orientation sensor that changes the screen between landscape and desktop, but also knows which side is up. His solution was to add a 12-axis sensor via the mini PCI express header.
The hardware comes in two pieces. The first is a mini-PCIe card to USB interface. This is handy if you want to add a Bluetooth dongle permanently to your computer. But he’s got other things in mind for it. After hacking the BIOS (which for some reason limits what you can plug into this slot) he moved onto the second part which is a USB 12-axis sensor. This picture shows the wires before they were soldered to the USB card. [Mal’oo] couldn’t just plug it in because the sensor wouldn’t have been oriented correctly in relation to the computer. The final product is quite response, as shown in the clip after the jump. Continue reading “12-axis sensor adds auto screen orientation to this older tablet PC”
[robomaniac] shows us how to modify a standard servo to allow continuous rotation. This is a classic robotics hack and has been around for a while, but we really like the way he put this together. Although you may need some soldering and desoldering tools to open the servo up, the hack is a physical one. All you really need to do is cut off a plastic tab on one of the gears. If you want to see an example of a bot you can build with one of these CR servos, he just posted this one motor walker.