LEDs again

[Steve Firth]

I was impressed by the R50 LED bulbs I tried recently so I decided to order some more. I spotted some bulbs that use 21 SMD LEDs rated at 3.5 watts. The interesting feature with these us that SMDs give a much wider angle of illumination than the standard LED. The bulbs are rated as 120° field of illumination. I also ordered some GU14 bulbs of the same wattage to try out.

Very impressed with both types, the R50s give a good strong white light (they are rated as "warm 3200K" but the light is on the blue side compared to tungsten or the old CFLs). Replacing one GU14 halogen 35W with an LED bulb gave an interesting comparison. The LED is much brighter when seen side by side. I can almost believe the makers claim that they are equivalent to 50W halogen.

The light is also more even than the halogens. I'll need to rewire the kitchen and remove two of the transformers to convert to all LED I think but that will be done sometime soon. I'm particularly keen to change to LED because I don't like how hot the halogens get.

The supplier was "Peritus" bought via Amazon. Extremely fast delivery. Ordered yesterday, on my desk this morning no postal charges.

[MaRKg123]

Hi, have you got the specific product link?

[Steve Firth]

MaRKg123 wrote: [snip]

This for the R50:

for the MR16

I said GU14 earlier - remembering bulb numbers isn't one of my skills.

For some reason Amazon are now charging postage. The same company also trades as "IvyShop" on eBay (seller mam4ap).

[Andrew Gabriel]

Tungsten and CFLs are 2700K. White LEDs at 2700K are, unfortunatelty, still comparatively inefficient (due to Stokes Shift), and given the manufacturers compete on efficiency, they don't want to produce 2700K parts. You can get 3000K if you search, but even that difference will be noticable in comparison to 2700K lighting. The efficient 2700K LED lights use an additional red LED to lower the colour temperature, but these have to hide the LEDs behind a diffuser to mix the colours, so they're no good as directional lighting, but work well as GLS retrofits. Obviously, higher colour temperatures can look natural, but they need much higher lighting levels (lux) to do so (lookup Kruithof Curve), which can be a challenge with LEDs, which is why installations often look blue-ish - the lux level is too low for the colour temperature.

Make sure you are comparing not by looking at the light, but by looking at what it is illuminating. Differences in beam angles can have an enormous impact, e.g. if a wider beam happens to hit a light coloured wall, versus a narrow beam only lighting a surface with low reflectivity (such as a carpet or floor, as commonly found with downlighters). Ideally, use a light meter on the working surface or object you are illuminating, and compare readings. For a kitchen where you do food preparation, also compare how food items appear under the lights. Raw meat can be difficult to light well enough to work on, with some higher colour temperature or discrete spectra (which was the original reason for pink fluorescent tubes in butchers).

[D.M.Chapman]

Interesting. Been pondering replacing the triple R50 spots in our kitchen with LED for a while, but not found anything anygood.

I assume

are the things?

Are they dimmer compatible? (I'm guessing not, but that would be a bonus).

Do they really compare well with a R50 bulb - similar spread etc?

Cheers,

Darren

[alan]

On 18/10/2012 22:26, Steve Firth wrote: I'm particularly keen to change to LED

In my experience the LEDs fail because the electronics in the base of the lamps get too hot. Before spending too much money operate the LEDs for a few months to see if they fail. One failure mechanism that I've seen is a dramatic dimming of one or more the LEDs in a multi LED cluster.

[Steve Firth]

,

Yes those are they. Also available on eBay same company different trading name.

No, says no dimmers on the pack. I don't have any dimmers.

To my eye yes. As Alan has said it seems a good idea to run some for a few months before I spend a lot on them. I'll report back on failures/dimming.