In the past few years, I have disassembled many LED bulb "flavors": standard (see "Disassembly: What killed this LED bulb?"), Zigbee control (see "Disassembly: Zigbee controlled LED bulbs"), Wi-Fi enhanced version (see "Teardown: Wi-Fi LED bulbs") and Bluetooth enhanced version (see "Teardown: Bluetooth enhanced LED bulbs"). I even recently analyzed another non-incandescent lamp method: compact fluorescent (CFL) bulbs (see "Teardown: What causes these CFL bulbs to fail?")!

One thing that the above bulbs have in common is that they only output "white" light-the color temperature is different, please note, but it is still a very "monochromatic" technical view. This time I think I should change it and use an LED bulb "Kodachrome" (as Paul Simon might say), which is not only dimmable when controlled by an external application, but also multi-color. Get to know Sengled’s smart LED bulbs:

I recently picked some of them and bundled them with various Amazon "smart" devices. This most recent example was found through a promotion on Prime Membership Day in 2021; I got the current-generation Echo Dot (the spherical successor to the device I removed a few months ago) for $24.99 (see "Teardown : Amazon Echo Dot improves sound performance")) and the theme of this disassembly. Considering that the normal standalone price is US$49.99 (Echo Dot) and US$14.99 (Sengled LED bulb), totaling US$64.98 (plus taxes and shipping, of course), this is really a big deal.

Please note that, as highlighted on the packaging, these bulbs can only be controlled by the Amazon Echo ecosystem (voice command devices and smartphone and tablet apps):

Note that, like Zigbee's predecessor, these collections can collaborate to create an extended range Bluetooth mesh network:

Except for the bulb itself, the contents of the box are very scarce, and only a brief quick start guide is provided:

The star, of course, is our A19-shaped patient, accompanied as usual with a 0.75 inch (19.1 mm) diameter cent coin for size comparison:

Followed by a close-up of the bottom and side markings:

I don't know you, but whenever I see the MAC address label on the bulb, I still do it twice! Other notable specifications (IMHO) include 9W (according to the product page on the Amazon website; 8.7W to be precise) and the claimed 60W/800 flow to understand the incandescent lamp equivalent, and the bulb will not only output a series of user configurable The color, but also can adjust the "white" color temperature range from 2000K to 6500K.

It's time to dive in. As usual, based on past experience, I turned to my hacksaw, which loosened the grip of the spherical adhesive, and I could pry it open with a flat-head (and other name) screwdriver as a lever arm:

Although the interior of the earth (see above) is unsurprisingly unremarkable, on the other hand, the things that illuminate it are much more interesting:

Surrounding it are 16 standard "white" LEDs, which are the type we have seen in other bulbs before. Inside the outer lighting ring (unsurprisingly) is another one, including a smaller number (eight) of full RGB LED structures. Passive and two sets of connectors (probably connected to the power and control circuits deep in the chassis through pins) complete this picture. And, oh yes, speaking of things connected to the "deep" circuit, you can't miss the bluetooth antenna that goes through the metal plate and above the metal plate, right?

Historically, it has sometimes been difficult to remove that plate to see what's inside. This time it was not bad, actually; I scraped off the remaining adhesive that originally fixed the globe to the chassis, and then used a smaller flat-head screwdriver to pry the board apart:

This is how the board looks like independently:

As expected, it is made of metal and works with the metal chassis to protect the environment (including the Bluetooth antenna) from radio frequency radiation from the analog and power circuits in the chassis:

In order to go further, again based on past experience, I need to first unscrew the base with pliers:

This now exposes the tip of the PCB (you may be able to see from the now empty solder joints, the original position of the red via line still connected to the base):

Pushing the tip overcomes the paste that holds the PCB in the chassis:

If you look inside the case now, you can see the bracket that originally held the PCB in place:

Moreover, after removing the remaining glue, with the help of some isopropyl alcohol, this is the first time we have seen the "guts" of the LED bulb circuit:

The two ICs on the right side of the photo on the bottom of the PCB (shown at the top of the image) are a bit mysterious. One of them labeled "BP1638" is (I think) an LED on/off/dimmer switch from a company called Bright Power Semiconductor. I can't find a reference to another one labeled "BP5711" anywhere. My best guess is that it comes from the same supplier, and they jointly control the two concentric LED rings shown earlier. If anyone has a more sensible idea, welcome to put your thoughts in the comments!

The positions of these two specific ICs match the horizontal metal plate on the top. At first (in retrospect, it was unwise) I suspected it might be a Faraday cage. When trying to pry open the top of it without success (I think it is actually a solidly connected heat sink), I did find an unexpected surprise: this particular part of the component is located on a unique miniature PCB :

However, I did not completely deviate from the base. There is a Faraday cage in the design, connected to one side of the antenna board (check the previous PCB overview photo, you will see it):

Photography is not impeccable, I realize, so you have to believe me. The main IC below is Telink’s TLSR8253, a Bluetooth v5 controller that supports Bluetooth Low Energy (BLE) and BLE Mesh topology, and 2.4 -GHz proprietary protocol. As I suspected, the hardware implementation is traditional; the Amazon ecosystem "lock" of smart LED bulbs is instead strengthened by bulbs and system-side software.

At this point, having just finished reading 1,000 words, it is time to end this particular project. As always, welcome your thoughts in the comments!

— Brian Dipert is the editor-in-chief of Embedded Vision Alliance, a senior analyst at BDTI and the editor-in-chief of InsideDSP, the company's online newsletter.

Watch out for that 7mh inductor! The cause of the Cree floodlight failure was an open circuit of the 8mh inductor. The inductor uses a very hard epoxy (?) temperature cycle to cold work the thin copper wire, which leads to brittle failure of the wire. The inductor in this lamp is covered with a heat shrink tube, so it may not be packaged.

I like perspective photos of engineering drawings. However, it would be great if these numbers had numbers and titles for reference. XY, Richard

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