Friday, February 22, 2013

T67 and T91/ Glimpse LED Lights Dimmer Video

This week I received twelve T91 LED lights, found in listing at ebay. At a price of $24.95 each and with free shipping, I was willing to take a chance on these "surplus" lights, not in original packaging, origin not explained. The ebay listing by New Life Electronics is regularly renewed, with seemingly an unlimited supply. In the box there were six of the original  T91/ Glimpse design, and six of the current, improved design.

With these lights, and with six T67s in addition, I am able to expand understanding of how LED disk/ plate lights behave when operated on a dimmer.

Here is a video of the operation of sixteen LED disk lights in parallel, controlled by one Cooper Wiring Devices D106P dimmer, Sixteen In Parallel.MP4  

Here is a back-side comparison of original and current T91/ 6" Glimpse lights:

Here are some conclusions from this testing:

  • The number of lights that may be operated from one dimmer is limited by the wattage rating of the dimmer. A 600 watt dimmer can operate forty 15 watt luminaires, carrying five amps.
  • The original T91/ Glimpse with two clunky power blocks is unacceptable on a dimmer, if there is more than one light. If you buy via the ebay link and intend to dim, demand newer version in communication with the seller. I think I got as many of the older version, as the seller thought I might tolerate.
  • One of the six older T91s failed in minutes of testing, never to fire again. This is the second failure of this kind I have seen. This is another reason to refuse buying the older version. I doubt I have recourse now, with the seller. I will want to break apart and examine one of the failed lights. I wish failures and fixes were freely discussed by manufacturers and their major distributors.
  • I had claimed the newer T91/ Glimpse has been cured of humming in a dimmer circuit. Not so! I have just never been able to hear the hum from any distance.
  • Seven T67s I have tested now on dimmers, have identical and objectionable hum, in  a dimmer circuit. It isn't a simple problem. LSGC did not in fact find a cure for Glimpse. Some smart person could figure out why the Glimpse lights make less noise. It may be a subtlety of mounting provisions and structure natural frequencies, vs. the AC power at 60 Hz.

I suggest there has been only one change of the 6" Glimpse/ T91 design. Please see my post, where I comment on visible differences. I call the two versions 6A and 6B.

Sunday, February 3, 2013

Attic Ladder Innovation

I am pushing harder than ever to influence design of residential attic ladders, where my interest is entirely in wood ladders, whether with an ordinary insulated door, or a fire-rated door. Here is an example of what I am after, in a wished-for ladder from prominent supplier Fakro.

Apply the same principles in a ladder for more-ordinary ceiling height:

Our homes and our needs are so varied. I am able to, and do, customize a ladder for each situation. The first freedom taken, is in lengths of intermediate sections. The second is in setting the ladder angle as I choose, as shallow as possible down to about 60°. I think the ordinary ladder has four sections, of lengths to suit our peculiar needs, with full attention to individual comfort and safety. I have three respected suppliers for USA installation of products FakroCalvert USA, and MidMade. All of these suppliers offer out-of-the-box ladders of three sections, of equal or nearly-equal length, and with wood ladders set a fixed angle. They despair of serving the specific need of any end-user.

Landing to the floor within space available and avoiding obstacles, is the complex need.  If you have begun and find a surprise, there must be a solution. If you could land the ladder more favorably at a steeper or shallower angle, you will want to. I speak mainly of an "unlucky bottom step", too close to the floor. Hit of a door header is another common unpleasant surprise. And, what if the bottom just doesn't quite reach the floor? With a hole in your ceiling, you must safely fulfill your commitment. There are supportive needs that will never be met by a big-box store or online seller, whether the product be that unique ladder, or bicycle.

I think attic ladders are similar in consumer demand, to bicycles. One size or flavor does not suit all. Besides facing unique needs, ladders are like bicycles in their fragility in shipment. Many manufacturers, and there are very many, serve only a local market. A manufacturer embracing bicycle-shop-like distribution, with safer and less-expensive shipping, could expand its market.

I have much more to say on this subject. Some of it is in the form of an open letter to manufacturers, as a page at my r5portals web site