On 06/01/15 06:10, John Robertson wrote:

As usual, heat is the enemy. Reading the technical specs for caps is
enlightening. They are rated usually at something like 2,000 to 5,000
hours at their rated temperature. So an 80C cap will die after something
like 2000 hrs at 80C or 4000 hours at 50C and 10000 hours at 40C (not
looking it up!), whereas a 105C cap will last 10000 hours at 85C, etc.
So, the better the grade of cap the longer it will last in warm to hot
environments. And there is the equivalent resistance and inductance to
consider as well. Some caps are much more tolerant of 50/60hz and others
are better at 20,000hz. Selecting those takes time and the cost
accountants slip in at some point...

Just out of interest, do any mains LEDs use simple reactive droppers, eg
capacitor or inductor, then bridge rectifier and smoothing capacitor?

And do 12V LEDs have driver circuits which are less stressed than their
mains equivalents? ie are 12V formats more likely to last longer?