Rick Hughes wrote:
On 03/02/2014 23:39, fred wrote:


Note that if you go for 20mA then you will limit your pulse resistor
size to about a quarter of the sizes I suggested (power = I sqrd x R),
you will be limited to 1k or so make sure you test for durability of
your non spec'd leds at those pulse levels before building in quantity.




OK went and ordered some 0.22uF X2 caps ... so when they arrive will try
them out ... so with the aim to be at 20mA, am I following you correctly
to use 1k 1/4 resistors ?

The problem now is not the wattage, it's the voltage across the
resistor. You need to use 4 off 400V rated resistors to avoid the
coating breaking down when a transient hits the circuit. Check the
resistor voltage ratings. There are some special high voltage reistors
around, Philips used to make some, Multicomp do some 1W carbon film
resistors which will withstand 1KV but only down to 1K I believe. You'd
need two of those in series.