Making my own radio

Written on July 6, 2009

While I am thinkering with stuff, I like to listen to the radio - more precisely to Studio Brussels. But sometimes I prefer to listen to one of my own CD's. Until now I've used the radio that I have received for my Solemn Communion about 10 years ago. This AM/FM radio is capable of playing audio cassettes and CD's. But I was growing tired of burning new compilations of about 20 songs or 80 minutes - the normal storage capacity of a 700 MB audio CD. This article will describe how I made myself a nice looking radio. But don't be fooled, I won't cover the internal electronics. Instead of starting from scratch, I built this radio from my previous car radio. So basically all I had to do was connecting the appropriate wires with 2 speakers and generating a voltage of 12 Volts. This radio would be a significant improvement because it has many other features and it's also capable of playing MP3 CD's, USB flash drives and SD/MMC cards.

Preparation

For starters you need some wooden plates and slats to build the casing. You also need a car radio, 2 simple speakers and a short stereo cable. Because normally a car radio is powered by a 12 Volts car battery, you should get yourself an AC/DC converter. The picture below displays my Axxion AR-501CD. You can observe an instruction manual, 2 connectors, the radio itself and the frontpanel.

Contents of the Axxion AR-501CD
Contents of the Axxion AR-501CD

Building the casing

This part takes the most time, depending on your sawing and nailing skills. Personally it took me about 6 hours without any sofisticated tools: a regular buzz saw, a drill, a hammer and some small nails. The following picture shows how I made the speaker holes - a 95 mm saw that can be mounted on any drill does the trick.

Hole saw
Hole saw

The dimensions of this casing can be chosen freely. Just take into account that all parts fit in. The dimensions I chose are 50x20x20 cm (width x length x height). It's quite a wide casing because my car radio was about 18 cm wide and both speakers were approximately 12 cm round.

Powering up

As stated before, a car radio should be powered by a 12 Volts power supply. First I tried to connect a 12 Volts power supply of an old scanner. Unfortunately this only outputs a current of 1.25 Amps. And as you all know from physics: power (in Watts) = voltage (in Volts) x current (in Amps). So a current of 1.25 Amps gives a power of 15 Watts, which is not enough to produce a decent sound. And too few Watts can also fry your power supply when playing loud sounds. To solve this problem I bought myself an AC/DC converter (see below). This converter outputs 5 Amps which is much better.

AC/DC convertor
AC/DC convertor

Connecting all parts

After mounting both speakers in the casing and fitting the radio into place, it's now time to connect all parts together. A normal car radio has 2 connectors, one for power concerns and one for the speakers. The instruction manual contains the necessary information about these connectors (see picture below).

Manual concerning installation
Manual concerning installation

You have to connect the left and right front speakers with the ones in the casing. The other speaker pins can later be used to connect 2 rear speakers. The power plug of this car radio has 4 wires. You have to connect both the memory and ignition key wire with the positive pole, and the ground wire with the negative pole. The fourth wire can be used for an antenna. I've used a 12 Volts universal connector that can easily be plugged into the AC/DC converter. The following picture displays such a connector.

12 Volts universal connector
12 Volts universal connector

Connecting the wires can be done several ways, just make sure you have a proper conduction. I've used a soldering iron to bind both adjoining copper parts securely together. The solder was pure tin. The picture below shows my soldering iron.

My soldering iron
My soldering iron

End result

To conclude this article, I'd like to share some photographs of the end result.

Frontal view with an open casing
Frontal view with an open casing

Top view
Top view

Close-up of connected wires
Close-up of connected wires

Rear view with a 12 Volts universal connector
Rear view with a 12 Volts universal connector

Frontal view with a closed casing
Frontal view with a closed casing

I've installed this radio in my basement, and I've also connected 2 rear speakers. However I'm still undecided whether to paint it or not. Perhaps in silver or black? Any suggestions are welcome. Anyway, I'm hoping this article might inspire others!