tag:blogger.com,1999:blog-789886813706673673.post3468893887595694076..comments2024-03-27T13:25:59.811+00:00Comments on Upper Thames Moths: 2020 so far; LED vs. actinic part 3Peter Hallhttp://www.blogger.com/profile/10828069795222628270noreply@blogger.comBlogger2125tag:blogger.com,1999:blog-789886813706673673.post-22356410020851703452020-07-03T00:33:37.668+01:002020-07-03T00:33:37.668+01:00Hi Dave, yes heat has to be taken into account. LE...Hi Dave, yes heat has to be taken into account. LEDs are (usually) far more efficient at converting electricity to light instead of heat than MV bulbs for example, but LEDs have their small size working against them in respect of being able to make the heat flow away.<br /><br />For example, the datasheet for my new ones gives Φe as 900mW with an electrical power input of a fraction below 2W. So that means about 1W of heat to dissipate, but the physical size of the substrate through which all that heat has to flow is only 3.5 mm square. Normally, that's not much of an issue because it can be dissipated by good contact with a heatsink: in fact, most low-power (domestic) LED lamps don't need a heatsink as such: they just use their metal fittings to conduct the heat away. My problem is that the best ways of making a good thermal contact usually involve permanent adhesive - and at the moment, I want to be able to take off one LED and substitute another as I tweak the design. That makes the thermal contact less effective, so the LED can't dissipate the heat as easily. Consequently, my heatsink is only at about 30°C when the LED itself is at 70°C.Tim Arnoldhttps://www.blogger.com/profile/15520211945274178431noreply@blogger.comtag:blogger.com,1999:blog-789886813706673673.post-41838915741645728032020-07-02T16:55:03.615+01:002020-07-02T16:55:03.615+01:00All very useful stuff, Tim, and it will be interes...All very useful stuff, Tim, and it will be interesting to see the results produced by a full year. I hadn't realised there was a problem with heat when using LEDs as a light source.Dave Wiltonhttps://www.blogger.com/profile/12533795070964851106noreply@blogger.com