Let there be light!

[pwdrive]

Not so much the chimney but the labyrinth for arsenic powder extraction, scroll down to an old picture here:

http://min-eng.blogspot.co.uk/2014_03_01_archive.html

When we used to drill through the stuff it had a garlic type of smell.

If you ever travel the road from St Ives to Penzance you'll see the remains of the engine house at Giew Mine, opposite that down in a valley slope you can see the chimney that was connected via a labyrinth to the Brunton calciner, I've been along that labyrinth, I used to live close by, it's an unusual one for Cornwall in that it's built with bricks and is square in section, the climbing irons are still in place inside it.

Here's an active 3D model showing the shafts, levels, raises and winzes for Devon Great Consols:

https://www.youtube.com/watch?v=9B5X-EXrgJQ

Here's some recent underground photo's taken in one section of that mine:

https://www.youtube.com/watch?v=t6YS0HhAWqA

Lawrence.

[Mark Hennessy]

We're gradually moving over to the LED panels at work, and so far we're impressed. Much better than the earlier LED replacement modules (that were too blue and too dim and poorly diffused). The control electronics has so-far been reliable, but as we know, the LEDs generally outlive the capacitors.

I'm tempted to buy one for the kitchen. I'm having to over-board the ceiling, so incorporating it into a flush design with some nice wooden trim would be quite easy, and it'll hopefully look like a diffused skylight. It's a north-facing room in a dark Victorian terrace, so will be used for large parts of the day as well as the evening. I'll get a 2 by 4 foot version, which will be positioned exactly over the small island (also 2 by 4 foot).

Even better, they are available in 1 foot widths. Just perfect for installation between the joists in my dark cellar with a very low ceiling. Light is a massive problem down there, but these seem like an excellent solution - far better than the custom slim (~40mm) fittings I've designed for T5 fluorescents - T5s are good, but LEDs are better today (not the case when I last investigated this, only 3-4 years back).

For now, I'm happy to procrastinate while the prices continue falling and the quality continues rising - meanwhile it makes sense to use up my existing stocks of lamps to some extent. Then those fittings can be moved to where they'll be used less frequently, like the garage and attic.

The only trouble is the switched-mode nature of the switchgear, but at least linear supplies (with big heat sinks!) can be built for task lighting while lining up radios, etc. Alternatively, a lot of lamps use capacitive dropper supplies with only minimal smoothing, so flicker terribly. Not everyone is bothered by this, but I am. When buying, it's not obvious which is which, and neither type is without problems. But the LEDs themselves? It's amazing how far we've come in such a short period of time.

[Refugee]

I am preparing to do the ceiling in the kitchen. It has the frame of a suspended ceiling previously made up like a shop or office.
My proposal is to replace the fiber tiles with laminate flooring bought as damaged packs from a DIY shack. The two foot square panels will just drop into the existing frame.
The toxic elements in LEDs are only present in trace amounts and are also encapsulated in silicon (glass) chips and will remain inert in land fill.
The chips are themselves encapsulated in plastic lenses. There should be no problem.

[pwdrive]

I hope those ceiling tiles aren't AIB.

Lawrence.

[Refugee]

The old ceiling tiles are long gone so they are no longer anything.

[pwdrive]

The old ceiling tiles are long gone so they are no longer anything.

That's good news, AIB can be nasty stuff if disturbed.

Lawrence.

[ppppenguin]

Unless you like cold light, always make sure you get warm white LEDs. Colour temperature typically 2700K to 3000K. 2700K is close to old filament bulbs, 3000K is close to halogens.

This morning I fitted a couple of trailing edge dimmers at a friend's house. They had bought a set of dimmable SES candle shaped LEDs for their living room light fittings. The previous bulbs were candle shape CFLs which took ages to warm up and weren't dimmable. They were delighted with the new LEDs. The dimming range was entirely adequate and no flicker at all. Another minor good thing about trailing edge dimmers is the absence of any audible buzz.

Tomorrow I'm fitting a couple of the Enlite low profile downlights in another friend's kitchen. They'll be in an alcove where there are currently a couple rather horrible little GU4 12V halogen fittings that suffer from bad contacts and bulb failures. I've got a 102mm holesaw which isn't quite big enugh so a little judicious work with a rasp is needed to accommodate the clips. They specify a 107mm hole which just isn't a standard size of holesaw. The next standard size, 111mm, would be a bit big.

I would like a LED solution for my own lounge lights. These are rather nice 1930s glass bowl fittings which I've fitted with 105W halogens. About 1900 lumens at full chat but they're on dimmers. I tried a dimmable 1520 lumen LED bulb but it's just not bright enough for some occasions. I suppose I could make up some brackets to fit a pair of 1050 lumen dimmable LEDs but it's quite a faff. Then change the dimmers to trailing edge types.

[Terry]

The toxic elements in LEDs are only present in trace amounts and are also encapsulated in silicon (glass) chips and will remain inert in land fill.

One way of disposing of low level radioactive waste which, in quantity, is still dangerous, is to embed small quantities in glass 'pebbles' to disperse the radiation to a safe level. The 'pebbles' are then used as hardcore in road building.

I believe that all the transistors that Clive Sinclair bought for all his various little radio kits were rejects otherwise going to be used for road building. I wouldn't suggest anyone that anyone divert a supply of the glass 'pebbles' for other purposes, though!

[Refugee]

The concentration of trace elements is 1 or 2 PPM. When I was in college in the 1970s it was drummed into us that it took a lot of work to get the silicon pure enough to be used in transistors and chips. There is likely to be enough in the impurities before the silicon is refined.
It all has to come out so that measured amounts can be added back in again. It is all taken for granted these days and if the press get hold of it they massively overrate the amount of the additives and start telling us we will all be poisoned.
There was a story of an event that took place in a tourist car park in the south west of England. An enthusiast took a radiation counter out and when he turned it on the pointer almost broke off. It was large lumps of natural local rock that had been rolled into position to stop cars being driven up a footpath. Whom on earth would test natural local stone when building a car park on a green field site?
They just test to find a location where the local radiation is below average and mix low level waste with whatever they can find including road stone.

[pwdrive]

It might have been Trenwith car park St. Ives, the old Trenwith mine is close by (Radium, M. Currie etc)

Lawrence.