Dimmer for 39mm 30w spots

[Invisible Man]

I have 3 of the above in an expensive display cabinet I do not want to mess about. They are downward facing and blow a bit too often. They run hot and are a little too bright anyway.

I did have an in-line dimmer but it got fried when one of them blew.

Anyone got any ideas on a robust dimmer or any other means of dimming them? They are plugged into a standard power socket.

I have still got a couple of soldering irons but got rid of all my ageing electronic components a few years back.

TIA for any ideas

[Tabby]

If all you want is to extend life, I'd try an inductor with shorting switch. Take 10 or 20v off the supply.

[Dave Plowman (News)]

I'm afraid there's not really a way of preventing this if a bulb shorts when it blows.

A suitable diode wired in series with them will reduce the output slightly but extend the life dramatically. Costs about 5p.

[Tabby]

It reduces power consumption of the lamp massively, and efficacy (read efficiancy) drops much faster than power does, so light output falls heavily. Add to that heavy flicker on a low wattage 240v filament and you've got an unhappy solution. It works much better in the US where

110v filaments are thicker, but still kills light output and energy efficiency badly.

NT

[Dave Plowman (News)]

I've never seen flicker on any tungsten filament bulb when using this trick. Although I've not tried it on a GLS type - why would you? But it works just fine on things like spots which are for effect rather than general lighting.