Take the alarm clock apart

To access the FM signal, we need to touch the motherboard inside first.

First, take off the bottom

Remove the CD drive

This is how it looks with the CD drive

This is how it looks once the CD drive is removed

This is the motherboard, it is where we will do the modifications.

Find FM Signal Path

Since we have already seen the motherboard, now we are able to find the FM signal path.

Different devices have different setups, so try to find your own audio signal path that you want to hack.

In this picture, I have already marked all the components related. Because I am going to modify the FM only, I will focus more on that switch. If you would like disable all of its original functions, you could modify the amplifier directly.

From the switch, all signals are separated and then go directly to the amplifier and then to the speaker.

After testing, I found out that this pin is for FM only. When switched to FM, it will be connected to other pins, so I will put the audio signal through this pin only.

Modify the Sound Card

At this step, we start to do some soldering. If you don't know how to solder, please research proper safety procedures.

This sound card is simple:

On the left is the headphone jack, on the right is the microphone.The three prongs in the jack are (from bottom to top) left, right, and ground.

The audio signals are coming out from the left and right of the sound card. Now I connect a wire between the left and right, called the "audio wire". Next I connect another wire to the ground and call it the "ground wire". Then I solder the wires onto sound card.

This picture only shows the left wire soldered. The right wire was soldered shortly after.

Step 4: Hack FM Audio Signal

Solder the audio wire where the FM audio signals go into the switch. Then solder the ground wire onto alarm clock's ground wire.

Here is the switch.

This picture does not look exactly the same as the next one, as I said, I did some further soldering on the right.

Then cut the trace connecting FM and the pin, so that FM signals will not interface with Airplay audio signals.

Reassemble

Follow the previous steps in reverse order to put the alarm clock back together.

Finish

Drill or cut a small hole in the back for the USB cable.

We are done!

And that's it! This is how we put Omega Airplay into practice, now, you are able to play music through an alarm clock! Keep in mind that you still need to connect Omega to a power source outside.

This guide was taken from the onion wiki.