Monthly Archives: September 2017

Free PCB coupon via Facebook to 2 random commenters

via Dangerous Prototypes

irtoyv3-600x369

Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. The coupon code usually go to Facebook ‘Other’ Messages Folder . More PCBs via Twitter on Tuesday and the blog every Sunday. Don’t forget there’s free PCBs three times every week:

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • We’ll contact you via Facebook with a coupon code for the PCB drawer.
  • Limit one PCB per address per month, please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.

Homemade 6 GHz FMCW radar

via Dangerous Prototypes

pfinished

Henrik Forstén has a nice build log on his newest version of this homemade 6 GHz FMCW radar:

Frequency Modulated Continuous Wave (FMCW) radar works by transmitting a chirp which frequency changes linearly with time. This chirp is then radiated with the antenna, reflected from the target and is received by the receiving antenna. On the reception side the received signal that was delayed and undelayed copy of the transmitted chirp are mixed (multiplied) together. The output of the mixer are two sine waves that have frequencies of sum and difference of the waveforms. The frequencies of the received signals are almost the same and the sum waveform has frequency of about two times of the original signal and is filtered out, but the difference waveform has frequency in kHz to few MHz range. The difference frequency is dependent on the delay of the received reflection signal making it possible to determine the delay of the reflected signal. The electromagnetic waves travel at speed of light which allows converting the delay to distance accurately. When there are several targets the output signal is sum of different frequencies and the distances to the targets can be recovered efficiently with Fourier transform.

See the full post on his blog. Project files are available at github.

Maker builds an Arduino-controlled, chess-playing robot

via Arduino Blog

While playing board games on a computer screen can be entertaining, this experience lacks a certain tangible aspect. YouTuber RoboAvatar decided to take things into the third dimension with a chess machine that uses an XYZ gantry system and gripper to move pieces as needed.

Instead of a vision system, RoboAvatar’s robotic device uses 64 reed switches (one for each square) to tell an Arduino Uno where the magnetized pieces reside. The project also features a Mux Shield and a pair of MCP23017 I/O expander chips, providing a total of 93 available pins.

While the Uno controls the physical motion and sensing of the board, a computer runs a Python program that does the chess game calculations and sends this information to it. You can see the machine demonstrated in the first video below. The second gives an overview of how it was made.

Want to build your own chess-playing robot? More details can be found over on Instructables.

How to build your own RS232 to TTL converter

via Dangerous Prototypes

pix4

A how-to on making a DIY RS232 to TTL converter by Jestine Yong:

As I read many pages on the internet I saw there is a sort of adapter so called “USB to TTL adapter” who can communicate through with the uC. I had not the time to order one but I give a try to make one for the COM port. Actually it is an RS232 to TTL converter which I found better from my opinion than that USB to TTL adapter.
Here is why I like more this RS232 to TTL adapter than the other one:

  • can be used on a real RS232 port
  • it is a stable voltage level converter
  • can be used on USB port too (through USB to RS232 converter)
  • there is no VCC ( somebody would say it’s a disadvantage but wait…) *
  • it is a real hardware stuff, no emulation etc. (if it is used through a real com port)
  • can be built really cheap and easy

More details at Electronics Repair site.

Aerial photography kite rig

via Pololu Blog

Pololu customer Yvon Hache made this 3D-printed aerial photography rig that he shared in a forum post. The rig, trailing 100 feet below the kite, automatically triggers a camera to take pictures at three tilt angles and sixteen pan angles. It incorporates an ARM Cortex-M4 microcontroller from Texas Instruments (32-bit, 80 MHz, TM4C123GH6PZ), an AltIMU-10 v5, Pololu voltage regulators, and a Zigbee module for wireless remote control. Yvon uses a pair of Pololu micro metal gearmotor extended brackets per motor—one mounts the motor to the frame and the other protects the encoder assembly.

More kite rig information and pictures can be found on Yvon’s website.

Algo-rhythmic PianoAI

via Raspberry Pi

It’s no secret that we love music projects at Pi Towers. On the contrary, we often shout it from the rooftops like we’re in Moulin Rouge! But the PianoAI project by Zack left us slack-jawed: he built an AI on a Raspberry Pi that listens to his piano playing, and then produces improvised, real-time accompaniment.

Jamming with PIanoAI (clip #1) (Version 1.0)

Another example of a short teaching and then jamming with piano with a version I’m more happy with. I have to play for the Pi for a little while before the Pi has enough data to make its own music.

The PianoAI

Inspired by a story about jazz musician Dan Tepfer, Zack set out to create an AI able to imitate his piano-playing style in real time. He began programming the AI in Python, before starting over in the open-source programming language Go.

The Go language gopher mascot with headphones and a MIDI keyboard

The Go mascot is a gopher. Why not?

Zack has published an excellent write-up of how he built PianoAI. It’s a very readable account of the progress he made and the obstacles he had to overcome while writing PianoAI, and it includes more example videos. It’s hard to add anything to Zack’s own words, so I shan’t try.

Paper notes for PianoAI algorithm

Some of Zack’s notes for his AI

If you just want to try out PianoAI, head over to his GitHub. He provides a detailed guide that talks you through how to implement and use it.

Music to our ears

The Raspberry Pi community never fails to amaze us with their wonderful builds, not least when it comes to musical ones. Check out this cool-looking synth by Toby Hendricks, this geometric instrument by David Sharples, and this pyrite-disc-reading music player by Dmitry Morozov. Aren’t they all splendid? And the list goes on and on

Which instrument do you play? The recorder? The ocarina? The jaw harp? Could you create an AI like Zack’s for it? Let us know in the comments below, and share your builds with us via social media.

The post Algo-rhythmic PianoAI appeared first on Raspberry Pi.