MR11 bulb specs

[seanrollins]

Has anybody experimented with MR11 halogen bulbs to find out what kind of pressures they'll take? The bulbs I'm curious about look like the typical mr16 with a reflector, except they also have a sealed lens across the front of them. I'm working on a canister light project and want to expose the mr11 bulb to water.

[Scoff]

Sean,

I have used all variations of the halogen diochroic bulbs (20 watt to 75 watt) open to FRESH water down to a depth of around 70metres (220ft) without any problems. But I would recommend covering the white 'paste' that holds the two pins in place with some 'superglue' before immersing in water, as the 'paste' softens & the pins come loose.

I prefer the bulbs without the front glass, and remove the glass if I cannot buy the former type (this requires some care with a pointy object to crack the glass then a pair of tweezers to remove it - all without breaking the reflector).

Plastic plumbing pipe adaptors make excellent bulb holders - though they can melt if used out of water for a few minutes.

I have no idea how long the bulbs would survive corrosion in saltwater...

Regards

Scoff
(Cave Diving Group Gt Britain)

[seanrollins]

Many thanks for the information Scoff. Is the bulb reflector still as effective if it is submerged? I suppose a light would still protect the bulbs from damage if banged etc.. I'll have to do some playing around.

Take care,

[Padipro]

The bulbs with the extra lens covers will flood if they are exposed to water and pressure.

When I was using the prototype light head for my DIY canister light the head flood once and the bulb filled up with water. The light still worked through out the dive but you could see the reflection off the water inside the bulb. If you could find a sealent that would stand up the heat you might be able to seal it and use it without any additional cover.

Scott

[seanrollins]

PADIPRO,

I'm going to go with your idea of using a mag lite. What a fantastic idea! I successfully machined out a light head on a cnc mill, and it turned out great, cept it takes far too long. I have to build a few of these things now cause friends are interested, so mag lite it is!

[Padipro]

Good luck, and please post some pics of your light on my site so we can all see how it turned out.

Scott

[seanrollins]

Will do. I'm currently waiting for my shipment from Sealco.

[Scoff]

Sean/ Scott

Nowadays the diochroics come with a flat glass front. I presume this is for safety reasons in normal usage. If you use them underwater without modification, water seeps in leaving a pool of water inside, which causes a 'wobbly' reflection in use, and then goes misty & diffuse with trapped water after. The old ones without a front glass were fine, and maintained the published beam pattern (I normally aim for 10 degree beam).

So you have two options - remove the glass entirely or drill holes in it to let water in then out againafter the dive.

Drilling two holes (top and bottom) about 3mm/ 1/8th inch will do the trick. However, tapping the front glass witha sharp point will break it, then pick out the bits of glass stuck/ glued to the edge. It may take you one or two tries to get the knack, but IMHO getting rid of the glass is the best way.

E-mail me direct (scoff_cavedivinggroup@hotmail.com) if you have further questions.

Cheers

Scoff

[j-valve]

One of my first home made light attempts was a little leaky and the bulb with the cover flooded. With a new bulb i epoxied the glass front on and went for another shot. Somehow the inside of the bulb had condensation on it. This is the only drawback I have found so far.

J