Best Buy’s new LED light bulb Part 1: Dimming vs. a 60W incandescent

Prices for LED light bulbs are dropping. 12 months ago you could expect to pay $50 for the Philips 60W-replacement LED bulb capable of 800 lumens and also dimmable. This week you can go to your local Best Buy and by a 60W-replacment LED lightbulb, also capable of 800 lumens and also dimmable – but only pay $17 for Best Buy’s house brand light bulb, called “Insignia”.

The bulb’s physical dimensions are reassuringly familiar, with an outline almost identical to an incandescent bulb, but it also has three aluminum heat sinks that extend upwards from the base.

Insignia LED light bulb next to 60W incandescent

This is a clever way to get the heat out of the base of the bulb, which is pretty tight real estate, and up to the relatively larger bulb area. The bulb lens itself is plastic. Other than that, there’s not much to say about the exterior of the bulb, so on to the next bulb characteristic: Dimming.

One of the biggest challenges in designing a LED bulb for the US residential market is dimming. TRIAC dimmers work great with incandescent lights, but LED bulbs require a sophisticated internal power supply to interpret the dimming voltage and current and respond smoothly to it. This power supply circuitry adds cost, and it also has to fit into a tiny space – the base of a lightbulb. In addition, there is no standard for a TRIAC switch: There are hundreds of different manufacturers and they all seem to implement TRIAC dimming slightly different. As a result, those early dimmable LED bulbs had a spotty track record of handling dimming power.

So the first thing I wanted to do with my new Insignia bulb was do a side-by-side comparison with an incandescent bulb and a dimmer switch. Rather than relying on my own ability to consistently and smoothly raise and lower the power to the bulbs, I used Lutron Maestro switch because of its programmable dimming feature: You can turn the switch on and off conventionally, but you can also set it so that that it gradually fades power on and off gradually.

Lutron Maestro intelligent dimming lighting controller

By plugging both bulbs into an outlet thats controlled by the Maestro TRIAC dimmer you can see how the Insignia compares dimming-wise to an incandescent: Here’s a video of the comparison.

Keep in mind that this is how the light looks to a digital camera, so the camera light sensor saturates a bit as the lights come full on, and then the sensor compensates.

What we’re looking for is that the LED bulb comes on at about the same point as the incandescent does as the power is ramping up, and that it falls off at about the same point, too. So few people use their dimmer switches for dimming (as opposed to a set-and-forget on/off switch) that it’s good to remember that even incandescent bulbs don’t dim evenly over the complete range of dimming.

Even two years ago we weren’t seeing such a nice dimming job in the dimmable LED bulbs, so props to the Insignia bulb for dimming so nicely.

Next up: Tear down –What’s inside? (Hint: it uses Cree LEDs.)


  1. says

    “One of the biggest challenges in designing a LED bulb for the US residential market is the requirement of the EnergyStar program that the bulbs be dimmable by the installed based of TRIAC dimming switches.”

    This is not true. ENERGY STAR Lamps Draft 3 Version 1.0 Specification does NOT require dimming.