Nathan Stratton’s Homepage

Portable 3 Watt 3G Video Phone and HotSpot

by on Jun.02, 2009, under Hardware

I love my BlinkMind Video Phone service, but one problem has been being able to make calls when I am camping. I started by looking for a 3G access point that was already supported by OpenWRT, a Linux distribution for embedded devices. Since I run the Linksys WRT54G at home, the WRT54G3G was a logical choice.

Get Linux Running

Getting Linux Running on the WRT54G3G can be a pain since it’s PCMCI implementation does not work on the 2.6 kernel series. To make matters worse, Sierra Wireless only wrote and supports drivers for the 2.6 kernel. You can grab a copy of OpenWRT White Russian here for the BCM47xx chip set, next grab a hex editor (I used shed on Fedora) and change the 4 bytes to W3GA, once that is done you should be able to fire up the unit and upgrade the firmware with the edited image. If your lazy you can just download this.

Add a LCD

I selected a 4 line X 20 Character LCD display that could be used to show the IP address, upload / download speed, and signal strength. Modern Device made a nice little serial to LCD board that makes it VERY easy to connect a LCD to any service device.

lcd117

Modern Device LCD117 Board

RT204-1 20x4 LCD

RT204-1 20x4 LCD

Download PDF Instructions

The WRT45G3G does not have an external serial port, but internally it does have pads for a 3.3V serial. If you wanted to drive a computer serial port you would need a level converter such as MAX232. However, the Modern Device board is able to accept 3.3V without a problem. The only catch was finding the right pin. I broke out a logic probe and send some data out the port in pulses to eventually find the pin.

Receive and Transmist pads

Receive and Transmist pads

Power

I wanted the system to be able to run off batter for at least a few hours so I decided to go with two 6V 6.5AH batteries in series rather then a single 12 volt battery. The size allowed them to lay down on the bottom of my case. The LCD runs off 5 Volts, the easiest way to make this work with parts on hand was to use a +5 Volt regulator that fit nicely on one of the 4 mounting screwed for the router. Current draw is low enough that no heat sink is needed. I also added a 12 volt LCD voltage meter to the mix so I could tell when my batteries were running low.

Two 6 Volt 6.5 AH Batteries

Two 6 Volt 6.5 AH Batteries

3G Wireless

3G is via Sierra Wireless 881 PCMCI 3G card with AT&T service. I quickly realized that the default signal strength was not going to cut it and an amplifier would be needed. After some digging I selected Wilson Electronics 801101 3 watt cellular amp with in conjunction with a ARC Wireless Solutions ARC-FR0803R30 antenna. With the antenna I was able to buy a cable to connect to the Sierra card, but it required a 6 foot FME Female – FME Female cable that I replaced with a 1 inch FME Female coupler.

Putting Parts Together

imgp1549

Portable 3 Watt 3G Video Phone and HotSpot

Back of router board

Back of router board

Closeup of status display and voltate meter

Closeup of status display and voltate meter

Software

I wanted the display to show some useful, current script runs at startup and displays IP address, upload and download avg bandwdith in kb/s, and Signal strength in dBm.

Download Script

imgp1546-2

Leave a Comment :, more...


Home Automation – Pool Fill

by on May.25, 2009, under Projects

I now can fill my pool without wasting water!

http://www.robotics.net/projects/home-automation/pool-fill

-Nathan

Leave a Comment : more...

Fun with PVC pipe

by on May.22, 2009, under Family

When I was a young I got a bag full of 3/4 PVC pipe cut to different lengths with a bunch of fittings for my birthday. It was such a cool gift! As a dad, I could not wait until I was able to do the same for my son. It only cost about $30 to get 20 feet of pipe, pack of 90^, pack of 45^, pack of Ts, 3 sprinkler heads, 2 3/4 valves, and a few other bits.

Joshua called it “Sprinkler Machine”

imgp1530

imgp1524

imgp1526

imgp1527

imgp1529

3 Comments :, , , more...

US LATA Map

by on May.22, 2009, under Telephony

Several people asked me to put back up my US LATA Map. This was made a long time ago, back when there were 7 RBOCs. 🙂

US LATA Map

US LATA Map

Leave a Comment :, more...

Mounting a 2.5″ hard drive in slim floppy bay

by on May.08, 2009, under Hardware

I have been looking for a way to move to removable 2.5″ boot/root disks on our servers. I am using all of the 3.5″ removable trays for storage leaving only a slim floppy bay in the case.

Supermicro 836S2-R800V

Supermicro 836S2-R800V

After much searching I found Thermaltake ST0002Z, a dual 2.5″ hot swap enclosure that mounts in a standard 3.5 inch floppy bay.

Thermaltake ST0002Z

Thermaltake ST0002Z

The two hot swap bays are actually 2 units that are bolted together making it very easy to take this apart and get yourself a nice 2.5 inch SATA bay that will fit in a slim floppy bay.

1 Comment :, more...

Looking for something?

Use the form below to search the site:

Cool Links!

A few highly recommended links...