Inspired by this article (German), I decided to build a kitchen radio from my old cell phone and some car speaker last year. Here’s how it turned out, combined with an instruction.
What you need
Here’s what you need. In the brackets I’ve stated my product choice. Of course, you can choose different products and colors.
- Wood (plywood for the panels, MDF for the linkage)
- Double AC power sockets for wall installation
- Color varnish (I used kiwi and light blue)
- Amplifier (I used the Kemo M033N)
- A 250V toggle switch (this one)
- An old cell phone (I used the Nokia Lumia 820)
- A car speaker (Sony Xplod XS-FB 1330)
- A 10 kOhm potentiometer with logarithmic taper (this one)
- A volume knob (this one)
- Plastic foots
- An audio cable with a TRS connector for your phone’s headphone jack
- Two fitting power adapters for cell phone and amplifier (I used the original cell phone adapter and for the amplifier, I used this one)
- Tools: Glue, luster terminals, screw clamps, drilling machine, jigsaw, soldering iron
What to do
Make a plan
He who fails to plan, plans to fail. I don’t remember who said that, but it’s true. Make a plan of the front panel and plot positions of bore holes and distances. Here’s what mine looked like:
Prepare the wood
Find a hardware store that saws the wood according to your parameters. I used plywood with a thickness of 6 mm. In my case, the dimensions were
- 200 x 280mm (front and back)
- 100 x 292 mm (top and bottom)
- 100 x 200 mm (left and right).
Be sure to make the casing deep enough so that there’s enough room for all the parts, especially for speaker and sockets.
Mark the lines and spots to drill on the wood with a pencil.
Then cut the holes for phone and speaker with a jigsaw.
Bore holes for volume dial and power switch.
Bore a hole at the bottom of the back panel for the power cable.
Build the casing
Apply the linkage pieces to the back of the front panel. To keep the phone stable in its dedicated position, you may apply some stabilizers around the phone. Apply screw clamps and let the glue dry.
Glue the side panels to the linkages of the front panel and apply linkages to the side panels. Keep the linkages stable with clamps. You can use paper tissues between clamp and the wood to prevent imprinting the colored wood.
When all is done, it should look like this:
You may notice here, that the transitions at the edges are not perfectly tight and make the top and bottom panels 2 or 3 mm longer for that.
Put the speaker in the casing and fasten it with screws. Ideally, the screws are included with the speaker. Same with the phone. To prevent it from dropping out when you touch it, you should fix it. I used two metal rods for that (see photo).
Install the AC sockets. I attached them to the bottom, next to the phone.
Screw potentiometer and switch in tight.
With the amplifier comes a manual that shows you how to connect it to power, input and speaker. Since the amplifier has only one channel, I’m using only the left channel of the headphone jacket.
Unfortunately, the Windows Phone 8.1 operating system does not allow to switch the audio output to mono, so I currently can hear only the left channel. Maybe your phone is smarter. By the way, this feature isn’t solely useful when building a mono radio, but also for people with hearing impaired. So come on, Microsoft!
Solder everything together and finally, put the two plugs in their socket. Test the radio before you close the casing up with the back panel.
Finally, you can screw the knob to the poti. I had to shorten the poti a bit with a pincer so that the knob was flush with the panel.
Prepare the phone
Install a radio app. I used radio.de which allows to pin radio stations to the start screen of your Windows Phone. I have also installed Spotify. You should pull the volume of the phone up to 100% so that our own hardware volume knob can work effectively.
I know, the design is special. And if you’re a dyed-in-the-wool audiophile, you probably won’t become friends with the sound. Another bummer is that the update from Windows Phone 8.0 to 8.1 has made it impossible to invoke the phone’s volume control by apps. There are only two ways left to do this now. The first is by pushing the hardware buttons on the right side of the phone. These are inaccessible now, of course. The other one is pulling in or out the power adapter when the phone is in stand-by. Windows Phone then shows a status panel from which you can go to the volume control and change it. This is a problem, because the system does not remember my settings.
All this is rather inconvenient. I’m looking forward to seeing what Windows 10 Mobile will bring to the table.
Besides that, it works!