This TV-B-Gone uses a 9V battery to send its signal through a matrix of 20 IR LEDS. This extends the working range of the device to about 90ft (line of sight). Using this in a regular sized room you are pretty much guaranteed to kill the TV no matter where you point it.
Step 1: Get the Stuff
You wont need much to build this, here is a list of the materials:
1 2N3904 Transistor (experiment with what you have around, it will probably work)
1 9V battery
1 9V battery holder
20 IR LED's
As far as tools go here is what I used:
soldering Iron + solder
If you dont have the TV-B-Gone already you can get one at the Make Store: http://makezine.com/store/
Step 2: Modify the TV-B-Gone
Take apart the TV-B-Gone and examine the board, you will notice it uses two sets of batteries. The two 3V batteries on top drive the LED's and the bottom 3V battery powers everything else. To save a little space we moved the 3V battery to the top holder and connected the stuff that was connected to the 6V supply to the 9V battery.
To get rid of the lower battery holder you have to use a sharp cutting tool to break the connection on the right side of the top battery holder. Then on the left side solder a wire from the big pad through the hole that is right next to it. Now you can remove the lower battery holder and move the bigger 3v battery to the top holder.
Step 3: Add Wires
Remove the IR LED that is on the TV-B-Gone and replace it with a pair of wires. Then solder wires for gnd and +9V in the two places shown in the photos below.
Step 4: Make the LED Array
Start with two LED's and decide which direction you will stitch. Bend the inside lead towards the second LED and solder it then repeat until you have a string of four LED's. Then repeat the entire process five times.
Now bend the leads of one set to the side and attach another set between the two bent leads. Repeat this until you have filled out the entire grid.
Note: Always check the polarity of the LED's you are soldering. This configuration creates five parallel blocks of four LED's in series.
Step 5: Complete the circuit
If you are looking at the flat side of a 2N3904 with the pins down the pins are called Emitter, Base, and Collector from left to right. Attach the Collector and the LED- connection from the TV-B-Gone PCB to the negative side of the LED array. Then connect the Base to the LED+ wire. Next connect the emitter to ground on the circuit board.
Now wire the positive side of the LED array to the 9V supply. Finally connect the ground and 9V wires from the PCB to the 9v Battery clip. Attach the LED array and PCB to the battery clip. You can use anything from around, duct tape will work nicely. I had some double stick foam so I used that. The End.