Step 9: Build the Electronics
The cathodes of the LEDs hook up to the outputs of the multiplexer, with the left column of LEDs being column 0. The demultiplexer needs to sink the LEDs one at a time, such as the one in the attached data sheet.
The anodes of the LEDs are attached to a cluster of 3 transistors. This is so the 1st transistor has the power directly from the adapter attached to its collector pin, the corresponding anode pin(from the microcontroller) is attached to the gate. It also has the emitter going directly to the gate of the 2nd transistor, and using a 1kOhm resistor it is connected to the gate of the 3rd transistor. The 2nd transistor has its collector attached to the green pin (pin 1 on the arduino) and its emitter attached to the green(or your highest draw LED) row. The 3rd transistor then has its collector attached to the red pin (pin 0 on arduino) and its emitter attached to the corresponding LED row. It should be noted that I ordered the LED rows from 0 at the top to 4 at the bottom.
The radio power is attached to the speaker pin (pin 9 on arduino), so that when the alarm is sounded it turns on and automagically tunes the strongest station.
The controller pins (analog pins 0-5) all have a 200kOhm pull-up resistor. the pins from 0-5 (followed by the corresponding DB9 number) attach to the controller in the following order: up(1), down(2), left(3), right(4), button1(5 and 6), button2(9, also optional). pin 7 on the DB9 connector is +5V and pin 8 is ground.
See the pictures for some comments and pointers, but if something is unclear let me know in the comments and I will do my best to help.
For the ports and LED rows and columns, I suggest installing sockets so the parts can be easily removed or swapped.
Now attach the wire to the LEDs, power and controller and test. Before you insert any chips make sure the power they are receiving is the correct 5V, so they aren't destroyed.