Bluetooth Audio Glasses
Introduction: Bluetooth Audio Glasses
This project was inspired by bose's audio sunglasses, (link) which usually cost around 200USD, and meant as a gift to a close friend of mine. I wanted to experiment and see if I could replicate a model at a cheaper cost.
There were no previous Instructables or tutorials I could really find on audio glasses so this project was quite challenging to navigate. But in the end, the design turned out quite nice, the circuit was relatively simple, and it works very well.
As for the actual project, to summarise it briefly, it is a pair of glasses with a hollowed-out frame in which the circuitry for Bluetooth earphones fit into. Therefore you can listen to music wirelessly while wearing the glasses.
Rough cost of the project: 10-12 USD
Time taken: 3-4 days
Complexity: 3/5
Supplies
There are a lot of parts required for this project however they are relatively accessible.
1) 1 x Male to Male Jumper Cable 40pcs. (link)
2) 1 x Old/unused earphones lying around the house. Aeroplane earphones will also work.
3) 2 x 150-ohm resistors (link)
4) 1 x 3.3k ohm resistor (link)
5) 1 x PAM8403 Audio amplifier board (link)
6) 1 x Bluetooth audio module. I used this (link), however afterwards I found out that this is a cheaper and newer alternative (link).
7) 1 x TP4056 charging module with protection. The model you buy should have over-discharge protection (link)
8) 1 x 300mAh small Li-po battery. I used this (link), but a thinner battery like this would be better (link)
9) 1 x Small Slider switch. I got mine from an old RC car. The width of the switch has to be 6mm or less
10) 10cm x 1.5mmHeat shrink tube (link)
11) 1 x Male berg strip 40pcs (link)
Tools and Equipment:
1) Soldering Iron + Soldering wire
2) Desoldering pump
3) Pliers
4) Wire cutters + Wire Strippers
5) 3D printer or access to a 3D printing service provider
Step 1: Supplies Photos
Step 2: Understanding the Circuit
There are only main parts to this circuit: Audio amplifier circuit, Bluetooth module, and charging module.
1) Charging module:
The TP4056 acts as the charging module, and it is connected to the rechargeable battery through B+ and B-. 485
The output pins on the charging module (OUT+ and OUT-) are connected to the Vcc and ground pins of the Bluetooth and audio amplifier module. This is how the circuit is powered.
Since the glasses are cordless, they will have to have a rechargeable battery in them, and hence, an appropriate circuit to charge and discharge the battery safely is also required, which is what the TP4056 does.
The board then changes the current and voltage to optimize charging up the battery. There is also a protection feature in the TP4056 board that prevents the rechargeable battery's voltage from becoming too high or too low.
Here is a good video explanation: link.
2) Bluetooth Audio module:
The Bluetooth module allows your device (phone/laptop/tablet) to connect wirelessly to the glasses through Bluetooth.
It has a Vcc and ground pin for power and 3 output pins corresponding to the left earphone, right earphone, and ground. These three pins are connected to the audio amplifier for the signal to be amplified and usable for earphones.
Once the Bluetooth audio module is powered up, it should appear on your phone's Bluetooth scanner as 3.0 BT or VIRE BT.
3) Audio amplifier:
The PAM8403 board is perhaps the cheapest and most effective audio amplifier board out there. It has three input pins that are connected to the Bluetoothmodule's three output pins. It also has 4 output pins, two for each speaker/earphone corresponding to the left and right side.
The output from the Bluetooth module is at a relatively high impedance while the speakers have a relatively low impedance. Therefore you were to connect the Bluetooth module directly to the earphones, without an audio amplifier, it would spoil the Bluetooth module's internal circuitry.
The earphones will try and draw way too much current from the Bluetooth module and there won't be enough voltage to power the speaker. That is why we need an audio amplifier. To provide the right intensity of current to the speaker.
The audio amplifier also has Vcc and GND pins to connect to a power source. It draws current from this to power the Speakers. Good website for explanation: https://www.headphonezone. 485