Echo Dot Activate trigger bracket

thingiverse

I wanted to find a way to get a trigger from the Dot as soon as the Activation word is spoken before the rest of any command. To accomplish this, I use a Light dependent resistor that picks up part of the Dot LED ring which lights up as soon as the activation word is said. This is fed into my Infra Red blaster which Alexa also controls. The LDR can be used to pull down a pin with a high value pull-up (e.g., 20K) or it can be passed through a single-stage FET buffer to give a more definite switch-over. For example, the LDR can go from 3.3V to gate, gate to 0V via 10K, source to 0V, drain to input pin and 4.7K load resistor to 3.3V. So Activation causes mute, command is spoken and system is unmuted at the completion of the command when light goes off. My esp8266 IR blaster code is available at https://github.com/roberttidey/IRBlasterWeb. The bracket here takes a GS55 LDR resistor to make it easier to put onto the Dot using a bit of tape to hold it in place. The LDR is over 300KOhm with LEDs off and goes down to about 6KOhm when LEDs come on. V2 bracket design has a slightly different shape with wider wings to cut down any stray light getting in and keeping dark current low.