On Fri, 26 Jun 2009 09:52:54 +0100, Raveninghorde
raveninghorde@invalid wrote:

On Thu, 25 Jun 2009 17:20:18 -0700, Capt. Cave Man
wrote:

On Thu, 25 Jun 2009 11:40:39 +0100, Raveninghorde raveninghorde@invalid
wrote:


Here is my new light bulb, minus reflector.

168 112 lumen leds in 14 strings.

The main problem is the aluminium of the pcb is not earthed causing
problems with current control presumably due to much higher stray
capacitance than we had on FR4. Just got to find a neat way of
earthing it.


Is there not a current limit resistor at each LED?

Capacitance has an effect? Improper design then.

Current limit resistors ARE the cheapest, most efficient "current
control".


No. Resistors are not efficient they dissipate and take board space,
they are not even particularly cheap at these power levels. The leds
take about 180 Watts.

You must be thinking of HPS luminaries and lamps. See ANSI standard
lamp codes S55 and S66.
LED power input for 19,000 lumens should be 30 watts or less.