I have done a similar project a few years back, but I didn't save photos to document that. Back then, the goal, which I achieved, was to build an energy-efficient night light.
Enough history... let's get started!
I started with a defective bulb. Remember the saying "a good start is half the success?" It's important to pick the right candidate for the project. Basic requirements are a moderately large base to house the electronics, a standard E27 screw base, and no visible damage.
The two candidates I got were Ikea-brand 7 Watt (Left) and Philips Genie 11 Watt (Right).
I started with the 7 W. Unfortunately, the glass enclosure which protects the fluorescent tubes cracked during the dismantling process. The 11 W opened up fine, thankfully. I used a pair of snip pliers to slowly and carefully cut at the groove that runs around the top end of the plastic body. Due to the hazardous contents inside the fluorescent tube, it is extremely important to cut slowly and carefully in order to avoid breakage of the tube.
The image above shows the empty base without the tubes and the electronic circuit inside it. The green wire is connected to the metal screw casing, while the white wire is connected to the bottom terminal.
On the right side of the image are two more items I used for this project. The black object is a [sanitized] plastic cap from a Listerine mouthwash. The yellow component is a 0.33 uF capacitor. It's X2-type and rated for use on 220V AC line voltage.
Before I continue, here is a friendly WARNING to any viewer who wishes to perform this project. Please read the disclaimer on this website. Do NOT attempt this unless you absolutely 100% understand what you are doing and what the risks are. This project involves line voltage that can serious hurt or kill you.
Speaking of capacitor, this project utilizes non-isolated capacitive power supply to power the LEDs. Such power supply concept is commonly found in places where the power requirement of the device is very low (like a smoke alarm connected to the AC line) and that a transformer or switch-mode power supply is too costly to implement.
The LEDs are from Nichia. Nichia is one of the best LED manufacturers. The four cool-white LED runs at approximately 10 mA constant-current, and outputs around 25000 mCd.
Because the circuit is non-isolated, the risk of electric shock is apparent. One way to deal with this risk is to eliminate the possibility of user contact to live components. In my case, the circuit is completely sealed inside the plastic casing. Components of the circuit, such as resistors and wires, are all set in place with hot glue. The two halves are permanently sealed together at the end.
The end product is bright, but nowhere as bright as the 11 Watt CFL. Still, it makes a nice night light and a great learning experience.
I will probably make a larger (and brighter) version of this in the future.
