Stop CFL lights from flashing

Picture of Stop CFL lights from flashing
When a compact fluorescent light bulb is being controlled by an illuminated wall switch, sometimes the CFL bulb will flash when the switch is off. This flashing is very noticeable when it's dark (a bedroom at night for example).

If you have a CFL bulb installed in an illuminated wall switch (these are switches that are lit when in the off position), this instructable can help stop the flashing.

First, why does the CFL bulb flash? Many times this is due to the circuit inside the CFL charging up, even when the bulb is off. This happens many times when the CFL bulb is being controlled by an illuminated wall switch, because the wall switch uses the CFL bulb itself as neutral. When the wall switch is on, the CFL bulb gets full line voltage. When the wall switch is off, the CFL bulb is the neutral for the light of the wall switch, causing a tiny current to flow through the CFL bulb.

This tiny current charges up the capacitor in the CFL bulb, until it releases it's energy. This cycle can repeat once every few seconds.
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Step 1:

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Materials you will need are a high quality soldering iron, and high quality tweezers. Also, solder is needed, and two 0805 sized (or similarly sized) resistors. A dremel tool or similar tool is needed also. You should be familiar with soldering. Keep in mind that anytime you work with electricity, care needs to be taken! Though not required, if you do not have experience with electrical wiring, do not attempt this instructable. If in doubt, talk to an expert (for example, an electrician).

To solve this flashing, what you want to do is put a bleeder resistor inbetween the two contacts of the light bulb. What this resistor does is cause the tiny current to pass through it, when the wall switch (or whatever causes the tiny current) is off, instead of charging the capacitor of the CFL and causing it to flash. This only works if the current is really small. If the bulb is flashing every second, the current may be too large for this to work effectively. In my case, the CFL bulb was flashing every 16 seconds, and 240k Ohms of resistance solved the flashing.

eli52 months ago

I was experiencing this problem, but had to find a different solution because I would not be able to apply those proposed here (I'm not an electrician nor I wanted to pay one for this kind of job). I wanted my nice CFL but didn't care about the illuminated switch. So I opened the switch and had a look. Luckily, the LED was easily accessible, just in front of me, with its tiny connections in the open. I (safely) broke one. All is working fine now: the CFL is not flashing anymore, nor is the switch illuminated anymore.

rimar20002 years ago
Clever. I have two questions:

1) When you change the bulb, you lost your enhancement. Is it possible to make it on the lamp socket instead of on the lamp?
2) Does Increase appreciably the electric intake this improvement?
tonytieger (author)  rimar20002 years ago
Good idea, this would not work when you changed the bulb. You could probably adapt this to the socket itself. In which case you could probably use a physically bigger resistor, and also place it more easily anywhere in the light fixture that's convenient.

As for the increase in load, it would be something really small (basically can be ignored), assuming 110V and 240k ohms, it would cause an additional 0.4mA or so of current, which equates to a wasted 0.04 watts.
Thanks, very much.

I've noticed that most of the energy saving bulbs do not last as long as the manufacturers promise.

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