Halogen lamp dies young

[timbuck2]

My bathroom 150w/230v Double Ended Linear Halogen Lamp has a very short working life with the constant on/off operations, thermal shock. I’m seeking an electronic dimmer circuit that automatically increases the loading from ‘0’ to full power to my lamp, within milliseconds every time it is switched on. If there is an advantage to reduce the loading slowly when switching off, I would like that to be also included. All contributions welcomed.

 

[MikeMl]

I use **broken link removed**. I dunno if they make them for 240V

 

[Tails]

Actually, what shortens the life of the lamp is the startup (each time you start your lamp, while the filament is still cold, a current overload occurs, as a cold filament is more conductive). The dimmer could be the solution, but do not dim the lamp too much because the lamp needs a certain temperature to maintain its halogen cycle (which regenerates the filament).

 

[Sceadwian]

What you need is a starter, a motor starter might be something you could use if it allows for soft start. Turn off time is irrelevant so it being abrupt shouldn't matter.

 

[PatM]

Make sure you don't touch the lamp with your bare fingers.
The oil on your skin will cause premature failure of any halogen lamp.

 

[Sceadwian]

So would condensation (bathroom)

 

[Diver300]

You should add one of these (or similar) in series with the lamp.
EPCOS|B57236S800M|THERMISTOR, NTC, 80R, 1.6A | Farnell United Kingdom

That is a thermistor. It's resistance is 80 Ω at room temperature. Your lamp has a resistance of around 350 Ω when hot, but it could be as low as 50 Ω when cold. That gives a huge surge current, so the 80 Ω in series will cut the start-up power a lot.

As the thermistor heats up, its resistance drops massively so you will only get 5 V drop or so in normal running.