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Wearable Raspberry Pi SMPS Modifications

SMPS Mods
SMPS Mods

A few modifications were required to the SMPS modules to make the power rails stable enough to run the Pi & it’s monitor. Without these the rails were so noisy that instability was being caused.

I have replaced the 100µF output capacitors & replaced them with 35v 4700µF caps. This provides a much lower output ripple.

There are also heatsinks attached to the converter ICs to help spread the heat.

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Wearable Raspberry Pi Part 2 – Power Supply

All Fitted
All Fitted

Progress is finally starting on the power supply unit for the Pi, fitted into the same case style as the Pi itself, this is an 8Ah Li-Poly battery pack with built in voltage regulation.

Regulator Boards
Regulator Boards

Here are the regulators, fixed to the top of the enclosure. These provide the 12v & 5v power rails for the Pi unit, at a max 3A per rail.

Battery Pack
Battery Pack

In the main body of the case the battery pack is fitted. This is made up of 4 3-cell Li-Poly RC battery packs, rated at 2Ah each. All wired in parallel this will provide a total of 8Ah at 12.6v when fully charged.

Powered Up
Powered Up

Here the regulators are powered up from a 13v supply for testing. I have discovered at full load these modules have very bad ripple, so I will be adding extra smoothing capacitors to the power rails to compensate for this.

I/O
I/O

Here are the connectors on the top of the unit, outputting the two power rails to the Pi & the DC barrel jack that will be used to charge the pack.

 

 

 

 

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Wearable Raspberry Pi Part 1

Overview
Overview

Here is the project I’m currently working on. A completely wearable computing platform based on the Raspberry Pi & the WiFi Pineapple.

Above can be seen the general overview of the current unit.

On the left:

  • Alfa AWUS036NHA USB High Power WiFi Network Interface
  • 512MB Model B Raspberry Pi, 16GB SD card, running Raspbian & LXDE Desktop. Overclocked to 1GHz.

On the right:

  • WiFi Pineapple router board
  • USB 3G card.

The WiFi, Pineapple & 3G all have external antenna connections for a better signal & the whole unit locks onto the belt with a pair of clips.
The Raspberry Pi is using the composite video output to the 7″ LCD I am using, running at a resolution of 640×480. This gives a decent amount of desktop space while retaining readability of the display.

The case itself is a Pelican 1050 hard case, with it’s rubber lining removed. The belt clips are also a custom addition.

Connections
Connections

Here are the connections to the main unit, on the left is the main power connector, supplying +5v & +12v DC. The plug on the right is an 8-pin connection that carries two channels of video, mono audio & +12v power to the display.
Currently the only antenna fitted is the 3G.

Connectors
Connectors

Closeup of the connections for power, audio & video. The toggle switch is redundant & will soon be replaced with a 3.5mm stereo jack for headphones, as an alternative to the mono audio built into the display.

Test Run
Test Run

Current state of test. Here the unit is running, provided with an internet connection through the Pineapple’s 3G radio, funneled into the Pi via it’s ethernet connection.

Pi Goodness!
Pi Goodness!

Running on a car reversing camera monitor at 640×480 resolution. This works fairly well for the size of the monitor & the text is still large enough to be readable.

 

Stay tuned for Part 2 where I will build the power supply unit.