Fluorescent Tube Illumination




Introduction: Fluorescent Tube Illumination

About: I am a University of Edinburgh electronics engineering student.

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!

Step 10: Flip the Switch and Enjoy

Enjoy your new light!

As you can see - Party is in progress.

Thanks for watching and let me know your ideas and suggestions.

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    27 Discussions

    It has been my experience inthe states, to replace the socket tothe screw type fluorescent fixtures it make life so much easier rather than diagnosing bulb, ballast, starter since the screw type ones are one piece plug and play.

    11 replies

    We live in a throw away society.
    Long tube fluorescent has bean the most efficiency light source sins the 50's.
    They have steadily gotten better, always ahead of everything but HID (wich isn't well suited for homes).
    4ft T8 (1 inch diameter) build vs a CFL
    20,000 hours...................... 8,000 hours
    2850 Lumens.....................2850 Lumens
    15$ a year#.........................$36 a year#

    *: The 32w rating on these bulbs are what is needed on the input side of a magnetic ballast to achieve the rated output. Using a high efficiency electronic ballast it could be as low as 24w. Any light bought it the last few years will have an electronic ballast, expect the draw to be about 28w, and as a bonus they don't hum.

    #Using 28w for the T8 running 12 hours a day, including bulb replacement costs. I didn't include Ballast replacement as they typically last 20 years.
    When electronic ballasts first came out they had problems, but they are good now, and sins they don't suffer from the faults of the old magnetic ballasts (the old magnetic ones would kill themselves if left on with a bad bulb) and when they do go, they are only $15.

    I agree. add to that that they are dirt cheap. I get a 36 Watt tube, including fixture, everything for 5 euro and they give an ocean of light.

    There's a new LED retrofit option. http://butterflyenergyworks.com/site/index.php?option=com_content&id=79

    40" length rated for 1200 lumens directional, 14W. the T8 tube's 2850 lumens is for the total light about. at least half of that has to be reflected, and a lot of the light is absorbed. Estimated $32 in electricity cost per 20" strip per lifetime (20 years at 50 hours a week)

    I've recently installed some these under by kitchen cabinets. they're really pretty great, and easy to install since there's 1 power supply and the wiring runs are all 24V DC.

    The bulbs you linked to are 600lm per bulb, that is almost 1/5 what a florescent will do, if you take into account loss in reflection you'd need 3 LED bulbs to match the one florescent, so hear's the comparison.

    LED vs. 4ft T8 (1 inch diameter) build vs a CFL
    50,000............20,000 hours............ 8,000 hours
    1800...............2850 lm......................2850 lm
    $150...............$5................................$18 Cost for bulbs
    $24.................$15 a year#................$36 a year#
    11.4................4.6................................1.8 lifetime, years

    LEDs are the future, but it's not there yet, if it where you'd see them lighting Walmart.

    Oh, if you build your own it's a lot cheaper, using these modules (or similar):

    These modules are rated at 600lm at 700ma, so the following numbers assume 3 modules.

    50,000 hours
    18.9w 21w with power supply losses
    $12.40 a year
    $14 year lifetime

    A power supply is needed, but if built properly it should last a lifetime. A 750kv supply in the basement could run low voltage power for the house.

    I picked 5028K as I prefer a cooler light similar to daylight.

    So, commercial LED lights aren't worthwhile, but if you build your own it may be, not much cheaper then florescent, but better for the environment.

    the LED's I linked are unique in that they are more of a DIY retrofit. they are no where near "commercial" with fancy housings and decorative lenses that you don't need to pay for when installing them in existing fixtures. it's also a small privately owned company. I would have fully DIY'd it, but for the price I couldn't beat these strips.

    Well, as I pointed out in the post you replied to, if you actually whent the diy route it would be worthwhile. The strips from that "small privately owned company" are overpriced.

    Changed my mind, a transformer-less supply inside every fixture would be better, no need to re-wire the place.

    you're missing one thing: the 2850lm rating is per 360 degree output, the 1800lm for the LED is ~160 degree output. you're wasting nearly half the of the florescent tube output with reflection and light going sideways where you can't use it. the LED's are plenty bright enough. the lumens per watt is not a a comparable rating as you have it. also 40" worth of LED is only 14 watts. your math is off somewhere.

    Here's a photo in a dark-ish room with single 7W 20" led strip where you'd normally have a 18W tube. https://picasaweb.google.com/112618105968052365253/Oct202012?authkey=Gv1sRgCOno5Lrf7vuANw#5783640813471250530

    LED's give more usable light per watt, rated lumens aren't everything.

    Powered at 24V DC, each strip produces ~600 lumens of light while consuming only 7.2W of electricity.

    That is a direct copy and paste from the link you provided.

    A single 48" florescent tube is 2850lm, if you take into account the fact that not all the light shining up is reflected down you get about 1800lm (63%) that is 3 strips.
    That is 21.6w.

    LED is the future definitely! It may come expensive as an investment in the beginning, but in the long term ... cheaper.

    Very ingenious, but I dont see anybody repeating thisany time soon. Much easier, cheaper and safer to change the socket, or the entire bathroom lamp

    Nice work. To make it more useful to less knowledgable people like me, could you comment more on the ballast, starter etc.? How did you know the ballast in the socket would work as replacement for what you took out of the new bulb?

    1 reply

    Very very very rougly the tube bulb you put on should have the same physical volume as the one you take off - this will match the lamps' power ratings.

    Also, if you take the starter out and inspect it you will notice the power ratings written on its side - this shall be taken into account. Mostly I think these values are wide enough to allow replacement bulbs to fit the power requirements.

    Did anyone consider that it would be a hundred times easier / more useful to modify the fixture, rather than the bulb?

    With this instructable, each and every bulb needs to be modified to fit -- and one isn't sure that the original driving circuitry for the large square bulb is appropriate for the compact fluorescent.

    It would be much much easier -- and much much more permanent to add a screw socket inside the old fixture in parallel with the existing circuitry (run from live and neutral), so that in the future, one could replace the bulb with a new one easily.

    I think I would have replaced the socket in the fixture to one that was compatible with the CFL bulb. If there were a next time, it would be screw out, screw in. This would have probably cost $2 - 3 and taken about the same amount of time or less.

    1 reply

    I see your point here, and I agree with that idea.

    I would only not agree with the timing - that replacement I did could take me 20 minutes maximum (behind the desk) and two climbs up the ladder.