Dimmable LED bulbs in touch lamp

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Dimmable LED bulbs in touch lamp

Postby piphil » January 8th, 2018, 2:48 pm

I have been converting all the lights in our house to LED bulbs. This has gone fairly smoothly, as 90% of the bulbs in the house are in simple on/off sockets.

The two places I've had issues are 1) in the bathrooms, where some of the sockets are in a circuit with the extractor fans, which really don't like the low-load LED replacements,* and 2) in the pair of touch-lamps on our bedside tables.

The touch lamps are fairly generic, and were cheap when we bought them about a decade ago. They have a metal base, which can be touched to turn the light on, twice more to raise the light level, and once more to turn it off.

The LED bulbs I've bought are "dimmable", but it seems "dimmable" means "dimmable if you have LED-compatible dimming circuitry". The bulbs turn on fine in the lamps, quite bright in brightness mode one, and are brighter in brightness mode 2. However, the highest brightness setting causes the bulbs to flicker annoyingly.

This wouldn't have been a deal breaker, but the lamps also suffer from another common LED bulb compatibility issue - they don't fully turn off. They give off a glow when they're supposed to be switched off, which looks a little like they're fluorescing. It's annoying enough that we've removed them and stuck the original incandescents back in - they're the only heat-small-metal-wire-up-until-it-glows technology left in the house. Well, apart from the toaster.

So here's my question - is there anything I can do to save our touch lamps from a trip to the dump? I understand that the powered-off glow is due to a leakage current through the bulbs, and this can be fixed by connecting a dump resistor to the circuit, I'm assuming in series with the bulb?

However, would this cause the touch part of the lamp to cease functioning? Is the tiny leakage current used to monitor the touch part of the mechanism? I have no clue how touch lamps work, in case you didn't gather that from this question...

Furthermore, would the resistor fix also fix the flicking third brightness stage? Would it tone down the first two stages as well? Before I open them up, I wanted to ask for advice on here to see if such a fix is even likely to work.

Thanks very much for any pointers, even if the pointer is "buy some new lamps!". However, I'd like to try and avoid throwing away perfectly good hardware if all it requires is a little tweaking....

* I put LED bulbs in my downstairs toilet, with both bulbs obviously connected to a circuit controlling the extractor fan. They flashed on and off like a disco, so I replaced the original halogen bulbs. The fan still works, but the lights now take 2-3 seconds to now come on, so I'm assuming I've damaged the lighting circuit. Therefore, a bonus question: what the hell have I done to my poor bathroom lighting...?
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