Pre story:

It all begun when the lamp in our bath started to blink like a disco lamp - blinking all the time. All of a sudden on the next day it did not have any signs of life ... it was dead.

We decided to simply replace it and went out to the store. Surprisingly the new replacement lamp was 10 pounds and we decided not to buy it from that shop :(

We went home sad ... and later that evening ... EUREKA !!! Why don't we use another lamp that I bought earlier this week just to have a spare one and it was only 30 pence, what a bargain I thought.

Not only it looks so cool, but it also works just perfect.

Step 1: Risk Evaluation

Reproducing the steps in this instructable may harm you.
Be careful when working with high voltage, take all possible safety actions.
You have to have appropriate knowledge and training.
Use the right tools.

Step 2: What? Why? How?

What? We will be replacing the square-like lamp with the other one. Firstly notice that the lamps have different connectors. One you screw in to the socket, one you simply push in to the socket. Not only the connectors, but also the characteristics of the electronic circuits!

Why? It has all to do with the construction of these lamps. They need special control circuit to limit the current through the tube, which would otherwise rise to destructive levels due to the tube's negative resistance characteristic [wikipedia]. (Read more in the links below)

How? The thing is that the fluorescent tube of our original lamp was separated from the starter and the ballast circuitry. On the other hand the new lamp had the starter and ballast circuitry attached to it, so it had to be separated.

Fluorescent lamps - read more
Starters for fluorescent lamps - read more
Ballast for fluorescent lamps - read more

Why was it not working? See the dark spot on the glass tube - this is the problem that caused the lamp to blink and then stop. This could be caused by a weak starter or ballast.

Step 3: Separate the Plastic Base

Extract the glass tubing from the lamp. It's not good to break it.

Remember how you cut the connections: one end of tube from left connections, other end of tube from the right connections.

We need the plastic base that has the connections on it.

Step 4: Separate the New Glass Tube

Extract the glass tubing from this lamp.

Unsolder the four wires that are soldered to the circuit.

Step 5: Soldering

Put 1-1.5cm long heat shrink tubes on the four cables.

Solder the cables of the new glass tubing to the old lamp's plastic holder.

Make sure you don't get the connections wrong. One end of tube to left connections, other end of tube to the right connections - just as before.

Step 6: Insulation

Heat to shrink the shrink tubes. This will insulate the soldered cables from each other.

Step 7: Ready

Put the plastic parts of the base together and we are ready!

It looks like a space ship now.

Step 8: Finishing Touches

I only added a wire to hold the front end not fall down.

Step 9: Climb Up to the Ceiling

Replace starter!
It's a matter of unscrewing the old one and screwing the new starter. Just make sure the wattage is OK. The new lamp we put was 11W, and the new starter can work with lamps in the range: 4-80W.

Now replace the new tubing to its place!