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This teardown is not a repair guide. To repair your Nest Protect, use our service manual.

  1. Nest Protect Teardown, Nest Protect Teardown: step 1, image 1 of 2 Nest Protect Teardown, Nest Protect Teardown: step 1, image 2 of 2
    • Welcome to the world, Nest Protect. Perhaps you will vanquish the ear melting, banshee cry of the over-excited smoke detectors installed in every home we've ever cooked in. Let's see what you're packing:

    • Available with 6 AA Energizer Ultimate Lithium batteries or Wired for 120 V

    • Wi-Fi connectivity and wireless mesh networking with other Nest units

    • Photoelectric smoke sensor and carbon monoxide sensor

    • Heat and humidity sensors

    • Three activity sensors

    • Ambient light sensor

  2. Nest Protect Teardown: step 2, image 1 of 1
    • The Nest Protect comes with a choice of power supply: battery or 120 V powered model.

    • Our battery powered detector claims its six AA Energizer Ultimate Lithium batteries have juice for "multi-year operation."

    • We definitely like the choice to use standard, readily available batteries—even if they won't need replacing for years.

  3. Nest Protect Teardown: step 3, image 1 of 2 Nest Protect Teardown: step 3, image 2 of 2
    • First stop: pop the top off the Nest button, the combination input switch and multi-colored sweeping light.

    • An ambient light sensor sits in the center of the button, with lenses in the translucent cover to increase its viewing angle.

    • A ring of RGB LEDs surround the sensor to make up the Protect's indicator glow:

    • White for the automatic night light

    • Reassuring green to indicate all's clear

    • Yellow for an early warning

    • Red for a get-out-of-town emergency

  4. Nest Protect Teardown: step 4, image 1 of 1
    • We pull out the impressive-for-a-smoke-detector main board, and the optical smoke detector is front and center, safely under its baffled shield.

    • The sensor is comprised of an infrared LED and a photodiode (light detector), angled in such a way that they're not in direct line of sight with each other.

    • As smoke enters the baffled chamber above the sensor, infrared light from the LED is scattered and reflected down into the photodiode, triggering the alarm. This sort of arrangement is standard practice for smoke detectors.

    • But applying the Nest Labs touch means adding all sorts of extra features for handling the alarm, like sending a notification to your smartphone that your house is on fire. Neat.

  5. Nest Protect Teardown: step 5, image 1 of 2 Nest Protect Teardown: step 5, image 2 of 2
    • A little further into the device, and we find the CO detector, disguised as a capacitor in a tiny metal barn.

    • The Figaro TGS5342 electrochemical carbon monoxide detector works like a little fuel cell—the presence of carbon monoxide drives a chemical reaction that generates current proportional to the CO concentration in the air.

    • The detector's measuring circuitry is on the reverse side of the main board, encased in some clear adhesive—likely to protect it against shock and the atmosphere.

  6. Nest Protect Teardown: step 6, image 1 of 1
    • If a fire or CO leak is detected, an 85 dB horn raises the alarm while a separate speaker tells you to exit the building in the talking-bomb-countdown-timer voice.

    • Straight and angled motion sensors catch your waving arm when you want to silence a false alarm from cooking smoke or a steamy shower.

  7. Nest Protect Teardown: step 7, image 1 of 1
    • Down now to the heart of the brain (Just ponder that metaphor for a moment. Done? Wonderful, let’s move on). A quick look at the noteworthy integrated circuits running the Nest Protect:

    • Freescale SCK60DN512VLL10 custom Kinetis K60 low-power 100 MHz MCU

    • Silicon Labs EM357 Ember Zigbee SoC

    • Freescale SCKL16Z128V custom Kinetis KL1x general purpose MCU

    • Texas Instruments LM324A quadruple op-amp

    • Murata Type ZX 2.4 GHz Wi-Fi 802.11b/g/n module (with Broadcom BCM43362 chipset)

    • Texas Instruments TPS62737 Step-Down Buck Converter

  8. Nest Protect Teardown: step 8, image 1 of 1
    • The Nest Protect is straight-forward and easy to disassemble. Common screw types, user-accessible batteries, and a simple design make it a very solid, repairable product.

    • That said, we won't be assigning a repairability score, considering you probably shouldn't do anything more than replace the batteries in your Nest Protect.

    • Nest Protect is a piece of safety equipment, and attempting to repair or modify it could result in inadvertent damage. This is one case where we support the old adage, "don't try this at home."


Any clue to what the 3rd wire on the socket is for? They only provide a two wire harness. My guess is related to the alarm integration -- possibly able to be used as an interconnect to existing alarms (if a 9V signal), too?

Robert Wojciechowski - Reply

This is a nice clean product! I like it! : ) Thanks for the teardown iFixIt!

Jonathan - Reply

And uses ninety six batteries lol

Steve think super - Reply

Any idea what the 4pins beside the USB port are for? JTag connector converter, perhaps?

Ben - Reply

I would like to know also.

benjamin.j.simon -

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