You like listening to radio and your favourite stations use Internet broadcasting? Or you’re sick of commercials between songs or the radio man spoiling the song with some announcement? Here is an award worthy project for you. With this wifi radio you have wireless connectivity to the Internet so you have a huge variety of radio stations to tune in, mp3 decoding, 44.1kHz 16 bit stereo audio, 4W amplifier with two 4 inch speakers, LCD display all this in a very nice vintage looking compact case. Total cost under 100$.
Asus WL-520GU was the choice for the wireless router. For under 50$ it’s a good platform for an embedded Linux system, its only shortcoming would be that it lacks built-in audio. This problem was solved with an USB audio adapter SYBA SD-CM-UAUD for 8$. Notice however the Asus router only supports USB 1.1 which is enough for audio, WL-500GP v2 can be used for USB 2.0. The router has a Broadcom BCM5354KFBG SoC CPU running at 200Mhz, 4MB flash and 16MB SRAM.
The most important part of the project is hacking the WL-520GU. Since it is just a router you will need to write new firmware to turn in into a wifi radio. This is done on the serial port which is pretty easy to access. The chosen open source Linux distribution that supports this router was OpenWRT. In the link you will find a precompiled image, thanks to the designer and builder of this project.
The LCD interface communicates with the WL-520GU by serial using ATmega168 microcontroller. On one of the analog inputs of the Atmel a potentiometer is connected and rotating the pot will make the radio jump to next station.
This is really an advanced project and i just love how it turned out. Lots of information on how to build one yourself is available in the link and I’m sure if you decide to go for it you will not regret it.
DIY Wifi Radio: [Link]
This project presents an audio synthesizer but not only that, it gives some ideas on how to interface other synths to a keyboard. The keyboard decoder uses the 74HC154 IC and the PIC18F1220. The 4 bits binary input of the 74HC154 is connected to the PIC which will cycle from 0 to 11, representing the twelve semitones. This in turn will cycle the outputs but with low logic level.
The octave is determined directly by the PIC. When a key is pressed it will make the corresponding octave line connect with the corresponding semitone output of the 74HC154 and thus turning the octave line from high to low level. When this is sensed by the PIC, it will check at which semitone the cycle was and output the musical note and the envelope trigger.
After that the PIC oscillators output are sent into separate wave shapers where you can select three types of waveforms. The waveforms are then summed and go into the VCF which can be controlled manually, by the envelope generator or modulated by oscillator 1. After VCF comes the VCA formed with a differential pair, with the control voltage modifying the emitter current.
Newer software has features like arpeggiator or portamento. With this way of interfacing the keyboard there will be some limitations to its usage. For example only the high note will be played if two notes are pressed the same time. All the instructions needed to build this are given however the code for the microcontroller is not but there is enough information to write it yourself.
Analog Synthesizer using PIC: [Link] – [Via]
If you like electro music and buttons here is something very good for you. A synthesizer that has 15 control knobs, 4 switches and 2 LEDs and still you can hold it in the palm of your hand. It allows you to shape all kinds of weird sounds and despite its big number of controls it is not a difficult project.
The sounds coming from this synthesizer are from four oscillators, usual inverters with an integrator in feedback. . You can control their rate of oscillation and modulate the pitch or volume, adjust the cut and resonance of low pass filters and feed the signal into a fuzz stage. By linking two dividers to the output of a LFO some interesting rhythms can be achieved.
Because we are dealing with oscillators you must be careful of how you wire and solder the electronic components or you will have to deal with stability problems. Also put the potentiometers’ shield to ground, easily done if your using a metal case. A 9V battery can power this synth for a a pretty long time.
The Drone Lab can give you more than awesome sounds by using the dividers’ outputs as gate outputs to some other devices. This way you can use the rhythmic modulator with other sound generators. Happy soldering.
Drone Lab Synthesizer: [Link] – [Via]
Nowadays the LCD and plasma technologies have become pretty cheap and big screen TV’s are more affordable. But your movie experience isn’t complete without good sound. DIY is a very good solution for a home theater speaker setup and subwoofers are the easiest component to build. Once you found a good speaker driver and made a cabinet according to it’s parameters all you need to do is give it a place in the whole system.
Active filters are the best solution to integrate the subwoofer in the HT. This way you add more control, flexibility and you eliminate negative influences of passive filters. The above circuit offers a very simple but effective solution. Using only a handful of electronic components cost is very low. The filter, as it is presented, has two main stages. The first stage, using half of the TL072 IC, sums the “left” and “right” channel into a single channel. By varying R3 you can adjust the gain.
The next stage forms the filter itself. It is a second order filter with 12db/octave slope. The corner frequency is set by the values of R5&7 between approximately 20Hz and 100Hz. You will need to set this frequency to match the other speakers, room and placement. If you don’t have any measuring equipment than trial and error is the way to go. Now there is one more thing you can do to make it really good. If you look at the first stage you will see that the signal will be 180 degrees shifted in phase. This may or may not affect your sound, it really depends on your room and speaker placement. However it would be good to add one simple inverter stage before the filter with gain set to 1 and with a bypass switch. This way you can select 0 or 180 degrees phase shift.
Subwoofer Active Filter: [Link]
A cool project for all those into the electro music. Here is something that even Jean Michel Jarre would want… an infrared Theremin-like musical instrument! Notes are vibrating from speakers just by moving your hands in thin air. One hand controls the note played and the other hand controls the octave. The difference is that the sensors are not antennas but two IR devices from Sharp, the GP2D120.
Notes are predefined, so unlike a Theremin, it’s pretty easy to play it. The instrument, named Squaremin, can only produce flat notes from the C major scale, so only C,D,E,F,G,A,B within 7 octaves. However you can change these notes to your desired scale, all you need to do is to define new notes by changing the period of the pulse in the source code. The microcontroller used is the ATmega168.
The operation of the instrument is given by the two IR sensors. These sensors can determine how close an object is to them by using triangulation. A pulse of IR light is emitted and if an object is in the way it reflects the light back to the sensor. A CCD array within the sensor receives the reflected light and determines the angle of this reflection. If the angle is wide it means the object is far and if the angle is narrow it means the object is close.
Therefore depending on the distance your hand is from the sensors, you change the notes and the octaves. The Squaremin has an internal audio amplifier with a small speaker but you can easily add a line out connector so you can hook the instrument to a mixer for example. Also it provides a little light show as it changes color with every note you play, again reminding of the awesome J.M. Jarre concerts.
All in all, although the spectral composition of each note is not that rich, this principle can be applied into a real instrument project that instead of microcontroller generated sounds plays real samples.
Infrared Theremin Musical Instrument: [Link] – [Via]
