On 13/03/18 12:40, The Natural Philosopher wrote:
On 13/03/18 10:27, Scott wrote:
Very helpful.Â* Mind is in a globe (bathroom light) but it is quite a
big globe.Â* I won't go overboard with output..

Short engineering dissertaion on heat dissipation.

What kills incandescent lamps is "hours on".

What kills lampshades is peak temperature. That why they have lamp
wattage ratings. 90% of an inmcandescent is heat so to a first
approximation a '60W lampshade' can take 60W of heat in its middle
without going brown or catching fire..

What kills LEDs is the product of life and of temperature. The hotter
they run the shorter they run.

However most LED *CHIPS* will stand to run at 100C or more.

What this means is that *NO* LED is going to scorch that lampshade. To
get 60W ofÂ* heat you probably need 80W of LED, and that probably will
not fit in the lampshade. And would blind you!


And don't forget LED "filament" strings with no PSU - there you should
be limited only to the led operation temperature without any problems
with silicon or capacitors not liking the heat.

On an aside, the only issue I've had with "filament" LEDs is that
different batches can dim at different rates on an LED dimmer (ie full
on all looks the same, but right down at the "just glowing" stage, one
set can be literally "just" glowing and the other can be quite a bit
brighter.

But overall, they look pleasant and the simplicity seems to help - I
have had almost no failures compared to lots of failures of PSU based
lamps in a similar time frame (couple of years).

But to be fair, this problem seems to abate with larger lamps - my R63's
are going strong after 2-3 years with zero failures.