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Raspberry Pi Radio Project - Scrapbook - Updated 05/03/2014

March 03, 2014 Benjamin Gray

When embarking on a project I tend to make a scrapbook style document of favourite projects in the subject area, a master document containing all the links I'll be plundering for information later. It seemed like a great idea to blog the whole lot and as soon as I saw this fantastic picture from Florian Amrhein my mind was made up, I had to share these projects before attempting my own! (found by way of Matt Richardson at Make).

Florian inherited a Philips 836A, which is a simple plywood case with a beautiful veneer, it had already had the innards removed - so this was not sacrilege. To this he added:

  • (a) Volume control: A pot
  • (b) Tuner: Another pot. Allows switching between radio stations. Connected to the Raspberry Pi (using an ADC on the daughter board).
  • (c) Display: 320x240 resolution, connected to composite socket of the Raspberry Pi.
  • (d) Power switch: Connected to mains and the transformer; Temporary isolated using cardboard.
  • (e) USB sound card
  • (f) USB Wifi stick
  • (g) single board computer
  • (h) Daughter board: Has some resistors for the buttons, capacitors and an ADC for the potentiometer, plus some sockets.
  • (i) Amplifier: Gets 24 Volts center tapped directly from the transformer (via the relay board).
  • (k) Rectifier and capacitor: provides about 16 VDC.
  • (m) Relay board: Allows to switch the amplifier on and off; is controlled by the Raspberry Pi.
  • (n) Transformer
  • (o) 5 VDC distribution (for Raspberry Pi and Wifi stick): Gets the power from the voltage regulator
  • (p) 16 VDC distribution (for the display and the voltage regulator)
  • (q) Cable connecting the speaker

The good news is we have most of these bits in stock, and the other bits probably should be stocked! 

Software wise it's running on Raspbian with the Music Player Daemon (good set up guide here it seems). Florian wrote his own UI in C and SDL. It looks great in his kitchen and at least one of the two I plan to make is likely to end up at home and will need approval from the boss. So maybe I should set up watch search on eBay for a Philips 836A.

 Not being able to find one for now the next example might be more up my street and be more achievable with the tools on hand. In particular our laser cutter.

This stunner came by way of DanNixon on instructables

Dan's project attributes first the Pandora Box which was published back in December 2010 which in Pi terms might make it the Grandfather of Raspberry Pi radios. 

The Pandora box is a good hacky start. Using a bunch of components that again importantly we stock. Electrical hardware needed:

1) Solderless breadboard (and wire)
2) Serial LCD module (3.3V module from Sparkfun was used: www.sparkfun.com/products/9067)
3) Ethernet Cable
4) USB Keyboard and mouse (necessary for setup, not the final product)
5) Pushbuttons (6) -  "Normally Open" type with threaded mounts
6) 3.3V Regulator (LM1117T-3.3 from Texas Instruments in the TO-220 package type used here)
7) Resistors: (7) ~10kOhm, (6) 1 kOhm
8) Capacitors: (2) 10 uF tantalum (as recommended by TI for 3.3V regulator
9) Pi T-Cobbler from Adafruit (not necessary, but makes GPIO access much easier)
10) Auxiliary audio cable

This is probably where I'll start, it uses Pianobar software wise. 

That was a bit of an interesting aside from the more aesthetically pleasing Radio of DanNixon. Dan's project uses

  • Arduino IC (i.e. ATmega 328 with Arduino bootloader, we can use the ISP Shield to program this)
  • Raspberry Pi (512MB version Dan didn't test with a 256MB version, but it should still work <-- will test with the model A)
  • Digital potentiometers (logarithmic taper (we'll be using it to attenuate audio) & i2c (from the Pi), a DS1807 will do)
  • Amplifiers (Dan used pre-built modules but feel free to build your own if you feel up to it)
  • DC-DC converters (12v to 5v, 600mA output, isolated)
  • Rotary encoders (from font panel, cursor movement and volume)
  • An LCD (4 rows, 20 columns works for me, if you have songs with really long names maybe get a 40 column one)

This build uses a custom board, it's KiCad so I can easily modify it. The load out of speakers and amp are fairly beefy but to be honest I've never really done much with audio so this could be very exciting.

For tonight these three projects are enough for the scrapbook. Should more be added I'll repost the blog in the usual places but also please watch this space. If you know of any other good builds let me know and I'll add them. 

Ok ok one more by way of the Raspberry Pi community on G+

Love the styling of this one!

Another beauty in cardboard has just surfaced by way of Reddit, the components of this one are:

  • Raspberry Pi model B
  • ST7565 LCD
  • 2 Rotary encoders
  • 4 digit, 7 segment display and a MAX72165124 driver
  • analogue panel meter
  • USB powered speakers
  • wifi dongle
  • cheap USB sound ‘card’ — on board audio conflicts with PWM GPIO
  • cardboard box

There's a beautiful write up of the work too. Check out plingboot. This last one probably deserves a full blog on its own. Every part is beautifully done and it's elegant and simple. Only downside is that the cardboard wouldn't last 5 minutes in my kitchen and my artistic skills aren't quite up to the job.

 

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