Piezoelectric sensors are great for monitoring mechanical impacts with a microcontroller. Whether you’re monitoring knocks on a door or watching a heartbeat, they are a cheap way to get the job done. They do have their downsides, though, so when [Jeremy] wanted to build an electronic drum set, he decided to use more expensive accelerometers to measure the percussive impacts instead.
Even though piezo sensors are cheap, they require a lot of work to get them working properly. The ADXL377 3-axis accelerometer that [Jeremy] found requires much less work, plus provides more reliable data due to a 1kHz low-pass filter at the output. In his setup, a Raspberry Pi handles all of the heavy lifting. An ADC on each drum sends data about each impact of the drum, and the Raspberry Pi outputs sound via the native Alsa driver and a USB sound card.
This project goes a long way to show how much simpler a project like this is once you find the right hardware for the job. [Jeremy]’s new electronic drums are very well documented as well if you are curious about using accelerometers on your newest project rather than piezo sensors. And, if you’re into drums be sure to see how you can have drums anywhere, or how you can build your own logic drums.
Continue reading “RaspiDrums Uses Expensive Sensors”
[Ivan] is fed up with all this rampant virtualization. When his company took away his physical desk phone in favor of using MS Lync, he was driven to build a USB rotary phone. His coworkers loved it and one of them asked [Ivan] to build another. The build log focuses on converting his coworker’s vintage brass and copper number that must weigh a ton.
He had to do a bit more work with this one because it had rusted out inside and a few of the contacts were bent. The good news is that the speaker and microphone were in working order and he was able to use them both. After restoring the stock functionality, he added a USB sound card and created a USB keyboard using a PIC32MX440F256H.
The rotary phone’s dial works using two switches, one that’s open and one that’s closed when no one is dialing. Once dialing is detected, the open switch closes and the closed switch clicks according to the dialed digit (ten clicks for 0). [Ivan] also reads the switch hook state and has added debouncing. This gave him some trouble because of the quick response expected by the PC bus, but he made use of interrupts and was allowed to keep his seat.
Please stay on the line. [Ivan]’s videos will be with you shortly.
Continue reading “USB Rotary Phone: A Lync to the Past”
A Remote Sphero-Control Trackball
Sphero is a cool little ball that can roll around under the control of a smartphone. Although super-cool by itself, in this application it’s been hacked into a sort of trackball to drive a remote control car!
Arduino Voice Control
[Sebastian] Wrote in to tell us about this article about using the Arduino EasyVR shield to add voice control to your project. Worth a look if it your application calls for voice-control.
OpenBeam Tiny 80/20-Like Extrusion
Openbeam is a Kickstarter project designed to produce an aluminium extrusion for building stuff. Although we’ve seen lots of this kind of thing, the small 15mm profile is quite interesting, and it’s designed to use off-the-shelf hardware, which should save on costs!
Hexapod + iPad = Fun for All
There’s not a lot of information on this hack, and the price or this hexapod device isn’t even listed, so we’ll assume it’s quite expensive. On the other hand, it’s got a cool video of it being controlled by an iPad, so maybe it will give you some hacking inspiration!
USB Sound Card Write-Up
[George] wrote in to tell us about his USB sound card write-up. Before you think that this is a dupe of this post, he freely admits to building it nearly identically to the one previously posted. Imitation may be the sincerest form of flattery, but [George] is also requesting some feedback on his blog and the aforementioned post. feel free to let him know what you think in the comments. Please be polite!