What’s in a… Compact Fluourescent Lightbulb?


“It came apart in me ‘and, honest Guv!”

First, a quick “Hello!” to everyone and a quick “Sorry!” for not having written anything for a while. I’m not sure where the time goes but, since my last post, I have been doing ‘things’ which seem to include not finishing the first draft of my third novel or figuring out what to do with the bits from… well what follows. I did build a snow dog…


A Miniature Snowzer

… but that probably isn’t relevant here so forget I mentioned it.

Whilst playing with Sam, a real flesh-and-blood dog, a light bulb was mortally injured and had to be put down, well, removed from the light fitting. Basically, the toy that I was throwing hit the hallway light and knocked the bulb out onto the carpet, where against all expectations and possibly a few laws of physics, it shattered. The bulb, not the carpet.


Opening the case is a Saw Point

Having cleaned up the glass (nasty in itself because of the thin mercury coating on the inside), I turned my attention to taking the rest of the thing apart. Actually, this was something I was intending to do and have had an old defunct bulb on my workbench for about a year now. Clearly this was a message from the universe telling me to stop waiting!

I had to saw the case in half – apparently other makes can be persuaded to open much more easily. This one, a cheap IKEA bulb, was moulded closed, presumably because it is easier to manufacture that way.


How the tube is connected


The Board with the nifty bits on









The components in this bulb will be similar to those in every type of lamp like this – even the mini CFL things we briefly used (they heat up so much that the holders warp and then they don’t work – a design flaw if ever there was one!). I think there will be a few slightly different components in the LED bulb that I bought and doesn’t work properly (unfortunately, the company I bought it from have failed to reply to my requests for a replacement).


In answer to the “What’s in” question…

Surprisingly, most of the components are standard sized ones – only a few resistors are the surface-mount variety, which is good because they are virtually unusable for hobbyists such as myself (you need a specialist soldering iron to remove them and re-use them easily).

From the left, the two things with three legs are transistors, then there are some inductors (coils of wire), a big capacitor (stores electric charge), five diodes, 3 small capacitors (store tiny amounts of charge) and a diac (that small blue thing, but probably wasn’t the one Suzanne Vega sung about). Below that is the circuit board and three surface-mount resistors.


There is a similar haul of components in the small CFL

The daft thing is that these electronic bits could be built into a holder that screwed into the light fitting (or just built into new light fittings), removing the need to have to keep building them. The bulbs would be easier to recycle then – just separate the base from the glass, and process the bits accordingly. At least one company can remove the mercury coating to produce safe, re-usable glass (well, it says so on their website so it must be true). I believe business premises have this arrangement in some places. Why not for the majority of users? Old fluorescent tubes had replaceable starters, after all.

I was hoping to have designed and built something using just these components and perhaps a solar cell, but haven’t managed to make something that works – yet. Watch this space!


Categories: recycling, repair, Sustainable Stuff | Tags: , , , , , | 8 Comments

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8 thoughts on “What’s in a… Compact Fluourescent Lightbulb?

  1. pat2727

    Oh, my, light bulbs certainly have become complicated over the years! Thanks for the demo and the idea. I haven’t taken anything apart in ages. There must be something around here that’s not serving any real purpose. Looking forward to your new creations.

    Liked by 1 person

  2. I’ve always wondered what the insides were like – it’s nice of you to show us all 🙂
    Let’s hope you can re-use the bits for something practical, hey? 🙂

    Liked by 1 person

    • I am hoping to attach a solar cell to some of the components to make something… not sure it will be very practical but there we are! I think the bits are there for an a.m. radio receiver but in this age of DAB that isn’t very exciting!

      Liked by 1 person

  3. By the way, get on with the proof-reading – I want to read your next book! Lol

    Liked by 1 person

    • Thank you, things like this just spur me on! Actually, I am still at the draft writing stage – I have the story largely sorted out in my head but it doesn’t want to come out onto the page yet – but it will. 🙂

      Liked by 1 person

  4. Pingback: ScrapHappy October 2021: Exorcising a Ghost in the Machine with a Light Bulb | writinghouse

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