In the process of building Tasca, there has been numerous iterations, prototypes in metal and plastic, tests to failure, drop and impact tests, electrical and electronic tests, and lighting application tests. As we found what worked, and what didn’t, and collected tooling for components, like the heat sink, I build the first functional products, using production level components. The first one made was what we affectionately call the Mule. It has been lighted 24/7 for one year as of the end of March, or a total of 8,841 logged hours to date. In that time it has been tested under operating conditions, attached to the side of a milling machine head, sprayed with lubricating and cleaning fluids, dropped, dunked, draped with rags under high ambient conditions, and frozen. As shown in the images here, this head has had a few hoods and shields attached to test effectiveness, and the mounting adapter has been changed a couple of times as I’ve experimented with the machined attachment hardware. This head has a thermocouple lead installed, so at any time I can plug it in to see what the temperature of the LED is, while there has been numerous output tests to check lumen depreciation, which has been less than 1% to date, right on track with the LM80 data for the LED (Bridgelux ES array).
This fixture has also been used as a baseline for testing the finished product as it has evolved. For example, we found that black anodizing og the heat sink lowered the LED temperature under identical operating conditions by as much as 10°C. We have also evolved the use of spring washers in the hinge, made small adjustments in the use of fasteners, and added the disconnect power connection to replace the Heyco cord entry – all found from actively working with the product and improving every detail.
The Mule will remain lighted and monitored along with others now being used in similar fashion with the latest components. While I do a great deal of individual component tests, like the effort we have put into finding the right power supply and driver combination, there is no substitute for testing and refining in use for developing a robust product. For example, we’ve found that under extreme temperatures, the pressure created between the extrusion and the glass lens creates small chips at the edges of the glass. We’ve corrected this by increasing the pocket depth and width provided in the extrusion, which has proven to eliminate the problem. In past tests, leading up to the Mule itself, we tested 6 different drivers on a dozen power supplies. We chose the driver we found to create the least amount of additional heat into the lighting head, matched to a power supply that results in 87% total efficiency at the highest operating temperature.
For more on this latest 12 in 12 project: 12 in 12 for 2012 – March
Or, visit the Tasca web site for complete Tasca product line details and specifications.