Echo Dot speaker intelligent control system solution

This project is able to control the speaker behavior. When a 3.5mm audio is plugged in, it disconnects the internal speaker.

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The $30 Echo Dot is a music streaming player that has a 3.5mm audio jack. The internal speaker is only good for things that respond to commands, I wouldn't use it to listen to music. The challenge is that when the 3.5mm jack is plugged in, it mutes the internal speaker. Unless you have an always-on amplifier, you'll end up missing out on Alexa responses. The typical use case I think of is an amplifier that's used for various inputs (music streaming, record player, but probably TV, CDs, etc.) and I switch to standby when not in use. So there's no guarantee that when you talk to Alexa, the amplifier will be on and connected to the right input at the same time; the internal speaker is always muted when the 3.5mm speaker is plugged in, and hearing the response I recognize should be a form of positive feedback.

Available functional options

Plug it into the 3.5mm jack when you listen to music, and unplug it when you're done. It's a simple, low-tech solution, but the convenience factor is zero.

If your amp supports it (or uses an external Bluetooth adapter), use Bluetooth. This is a little more convenient, as you can have Alexa connect to your Bluetooth device when you want to listen to music; definitely better than plugging/unplugging cables, but still an extra step. Also, your audio quality will be slightly lower depending on your device configuration (e.g. when using an external Bluetooth adapter), and Bluetooth may still be connected even when the amp is off, again routing the audio to nowhere.

The solution I came up with was when I gained control over the internal speaker behavior. This involves modifications to Alexa so may not be for everyone. But offers the most flexibility.

My Solution

The Echo Dot uses a 3.5mm connector, which breaks out two pairs of pins when the jack is plugged in. The solution is relatively simple: connect a cable to those pin pairs and decide when to activate the internal speaker. Depending on your configuration and complexity, there are several options:

Short the two pairs permanently. You can simplify the project and avoid any mechanical modifications to the device by shorting these pins directly on the PCB for this purpose. The downside is that the built-in speaker will always be on, so if you want to listen to music on a super hi-fi Hi-Fi device, for example, you will hear the annoying echo of the music coming from the Echo speaker.

If your amplifier has a 12V output trigger that can be configured to a specified input (so the voltage is only present when the amplifier is on and the specific input the Echo Dot is connected to is selected), then the simplest solution might be to buy a 2-channel 12V relay controlled via the amplifier output trigger. My amplifier does have an output trigger, but it can only be configured to turn the amplifier on/off as a whole, for any input. So in my case, I needed a different setup.

When I chose the input to which the Echo Dot was connected, the controller already knew that, so it was a simple matter of activating a pin on the Particle Photon which would direct a 2-channel relay to disconnect the internal speakers when the stereo was activated.

Disassembling the Echo Dot

Taking the Dot apart isn't that hard. But things will never be the same again; there's a sticky rubber pad that can be put back on, but it will show that it's been removed. There's also some drilling, soldering, and cutting involved. As I warned at the outset, this involves working with delicate electronics, so you run the risk of bricking the device.

Gently remove the rubber pad on the bottom. Just pry it off and it will peel off.

After removing the rubber pad, there is still a clear foil stuck to the bottom. To access the screws, I just drilled holes in that foil. Using a Torx screwdriver, remove the screws. Open the device carefully.

welding

Next comes the tricky part. The pins on the 3.5mm connector are very small, so be very careful. The cable needs to be soldered to the pins marked 1-4 in the picture above. If you short pins 1&2 and 3&4, the internal speaker will turn on even if the 3.5mm jack is plugged in. As I explained in the "My Solution" section, there are multiple options for how and when to turn the internal speaker on/off.

Same view as welding cable.

Mechanical work

In order to get the cables out, some modifications were required.

First, the inner skeleton looks like magnesium alloy (which, by the way, is pretty amazing for a device at this price point). It's necessary to remove a little below where the connector is to get the cable out. I used a Dremel, but it didn't work.

Next you need to cut openings in the plastic casing to allow the cables to come out.

Just to make sure the cable was secure, I applied a little glue and isolated it on the top

Finally, put it all together

Schematic diagram:

The connections are as follows (Relay -> Photon), please note that the jumper RY-VCC/VCC must be removed in this configuration:

VCC -> 3.3V

RY-VCC -> Vehicle Identification Number

IN1 -> GPIO D4

IN2 -> GPIO D4 (I switched from the same GPIO; if you want to be safe from overloading, you can switch from e.g. D5 and just program the pin to mirror D4)

Grounding - > Grounding

Then using Alexa connect what I marked 1&2 to J1 1&2 and 3&4 to J2 1&2 (these are normally closed so the internal speakers will be active even if powered off).

Additionally, I use a 12V trigger for the amplifier. This ensures that when the amplifier is manually turned off, it resets Alexa to the internal speaker.

Final Result: