back to index

Reverse engineering: EuroLite 15W CFL

EuroLite 15W CFL

A humble lightbulb is being ousted by a CFL. In addition to obvious drawbacks like warm-up period and crappy light color, there is a hidden benefit: recovery of parts after the bulb dies.

This one dead bulb was dissected and examined. The interesting feature of the bulb shape is that the bulb itself is made of opal glass, and hides a conventional bent-tube CFL.

To remove the bulb from the socket, the plastic edge was gently heated with hot air and even more gently pried away from the bulb while soft. It is easy to crack the glass bulb here (and it can be useful later), so appropriate patience and care is required. Just enough distance to disrupt the direct contact of the plastic with the glass is needed. It is also easy to overheat and burn the plastic; the image shows a mark of exactly that mishap when the material's characteristics were still unfamiliar.

This one CFL failed by burnout of one of the filaments in the tube.

The circuitboard contains several parts worth the effort of getting to them. In addition to common "dirt" like 1N4007 diodes and some capacitors, there is a small ferrite toroid (the transformer for control of the transistors), the choke (a fairly big double-E core made of ferrite that can be taken apart and rewound), a 32V diac (DB3 BL), and 2.7nF capacitor rated at 1000 volts.

The bulb housing could also have some uses; the glass bulb may be useful for arts or novelty objects, the base with the thread can house mains-connected circuits powered from a lightbulb socket.

Images


Outside view

inside, board bottom

Inside, board and tube bottom

Removed bulb, removed base, board top

Parts layout

Schematics

If you have any comments or questions about the topic, please let me know here:
Your name:
Your email:
Spambait
Leave this empty!
Only spambots enter stuff here.
Feedback: