Project

# Title Team Members TA Documents Sponsor
53 Portable Bluetooth Amp for Home Speakers
Anthony Pham
Austin Palanca
Nicholas Jew
Zhen Qin other
proposal
Anthony Pham - anpham2
Nicholas Jew - njew2
Austin Palanca - palanca2

The Idea -
Our project looks to create a battery powered bluetooth amplifier for regular everyday home speakers. While there are bluetooth speakers out in the market, for those who have bookshelf speakers, or towers in their home setup, they can repurpose their speakers on the go by using this device. For speakers with banana plugs, you can easily unplug your speakers and connect this device to use on the go.

The Inspiration -
I thought of this idea when I was going to dance practice and we used a $80 bluetooth speaker, 2x10w woofers. Although it is small, the downside is that there is not a big enough cabinet to reproduce low end sound. Also, most bluetooth speakers I have listened to from Bose, JBL, and Harmon Kardon have very muddy mids or highs due to them not using tweeters.

“Portability” comes to mind when developing this idea. However, for this case, portability just entails that we can move the device without hassle and leave it in place once it is setup. For example, carrying the speaker to the gym, park, or dance practice room.

So I thought, my speakers at home are pretty nice, however I’d have to remove my receiver which requires my to disconnect my entire setup. So I thought about how easy it is to unplug and replug in banana plugs and thought it would be interesting to make a portable amp that supports these connections. Of course for older speakers without banana plugs, they can remove the banana plugs and connect the cable directly to the speaker clips.

Design -
The device consists of a bluetooth chip, amp/dac chip, charging controller, battery, charging port, banana plug female to pcb, and the chassis.

The bluetooth chip we are looking into is the CC2564MODN or the CC2564MODA from TI. The difference between the two is that one has an integrated chip antenna and the other allows us to use our own antenna, for example a pcb printed antenna. However, this selection requires more research depending on the chassis.

The amp/dac that we are looking for is one that can operate with 20~40w @8ohm mono with an i2S, Inter-IC Sound, bus to communicate with the bluetooth chip. We would use the bluetooth chip as the master clock, and send its clock to the dac as a slave. We are also looking at a Class D amplifier due to it having a better efficiency than AB amplifiers. Although this causes more distortion, it should be above frequency ranges above audible levels. We are looking to ask TI if we can get 5 evaluation modules for their next gen series chip as they currently are in pre-production, but in the meantime we will purchase something like a TAS5731PHP as we don't know the turnaround time/cost for a new chip.

The Battery -
The battery needs to have a decent capacity and maximum output power, while also not being too heavy to carry around. Small sealed lead acid batteries (SLA) typically found in uninterrupted power supplies (UPS) would work, although they are usually very heavy for their capacity. Instead, we would use lithium batteries, which have good energy density and output power while also being lightweight. We will also integrate charging of the battery into the device using a lithium charging circuit, like TI’s BQ24616 chip.

The Housing -
For the chassis, we are looking at having a plastic housing for the device to reduce capturing noise. However, we do notice that although class D amps are efficient, there is still heat that needs to be dissipated. Assuming 94% efficiency according to Texas Instruments’ TPA3244 Amp chip, we can expect about 2.4 watts of heat from the chip itself. If using the PCB as a heatsink is not sufficient with passive cooling (slits through the chassis), we can look at creating a metal chassis with an external bluetooth antenna, or have a low rpm fan to move airflow inside of the chassis.

Prosthetic Control Board

Caleb Albers, Daniel Lee

Prosthetic Control Board

Featured Project

Psyonic is a local start-up that has been working on a prosthetic arm with an impressive set of features as well as being affordable. The current iteration of the main hand board is functional, but has limitations in computational power as well as scalability. In lieu of this, Psyonic wishes to switch to a production-ready chip that is an improvement on the current micro controller by utilizing a more modern architecture. During this change a few new features would be added that would improve safety, allow for easier debugging, and fix some issues present in the current implementation. The board is also slated to communicate with several other boards found in the hand. Additionally we are looking at the possibility of improving the longevity of the product with methods such as conformal coating and potting.

Core Functionality:

Replace microcontroller, change connectors, and code software to send control signals to the motor drivers

Tier 1 functions:

Add additional communication interfaces (I2C), and add temperature sensor.

Tier 2 functions:

Setup framework for communication between other boards, and improve board longevity.

Overview of proposed changes by affected area:

Microcontroller/Architecture Change:

Teensy -> Production-ready chip (most likely ARM based, i.e. STM32 family of processors)

Board:

support new microcontroller, adding additional communication interfaces (I2C), change to more robust connector. (will need to design pcb for both main control as well as finger sensors)

Sensor:

Addition of a temperature sensor to provide temperature feedback to the microcontroller.

Software:

change from Arduino IDE to new toolchain. (ARM has various base libraries such as mbed and can be configured for use with eclipse to act as IDE) Lay out framework to allow communication from other boards found in other parts of the arm.