On Thu, 25 Jun 2009 07:11:19 -0400, Spehro Pefhany
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.

That is aluminum clad? There are holes through it? Are they isolated?

The only holes are mechanical fixing holes, none go through the
copper.

To complete the prototype I'm removing the insulation layer around a
couple of holes to give bare aluminium on the top and creating an ac
ground with capacitors from 0V and +50V to solder tags secured by the
mounting srews.