1.2 kW RC Battery Charger

Submitted by Matt on Sat, 05/09/2015 - 11:00

My drone has a flight time of 15-20 minutes, but nevertheless goes through batteries at a tremendous rate. I can have extras standing by, but after a while it gets to be a bit ridiculous with the amount of batteries (lose track of which ones are dead/alive, have to carry them all around, etc).

Lithium Ion/Poly battery chargers are fairly expensive, and for the most part very very slow. Also consumer level models designed with lots of generalities, not taking advantage of special aspects of a given battery role, so they tend to charge conservatively. And even then they can only charge one "battery" at a time, even though the battery may consist of one or more cells.

I wanted to bypass all of this and use my electrical knowledge and design a super fast charger. My first challenge I had to solve was I needed a high power DC source. You can buy expensive lab versions of these, but a computer PSU works just fine! So I acquired an old 1.2 kW server power supply for the task at minimum expense off of ebay. The power supply indicates that it supplies a rail voltage of +12. My batteries are 3 cell lithium ion batteries have a terminal voltage fully charged of around that. Great! I might not even need to convert DC-DC.

If any of you have ever worked with computer/server power supplies before, you know that you have to get the power supply to turn "on" before you can start pulling power from it. So I had to find the signal pins on the PSU, and make a switch to enable it to turn on at will. After some short searching online, I found the method with little issue. After measuring the terminal voltage of the supply, I came out with 12.4 V. This is almost ideal! The 3 cell batteries have a fully charged voltage of 12.6. So what this means if you are looking at the charge curve of a lithium battery cell, I will be able to charge each cell to about 90%.

Multi Headed Hypervisor Server

Submitted by Matt on Tue, 04/14/2015 - 20:36

So, being in the server tech business I have access to special high performance hardware. This gives me a special opportunity to fool around with enterprise level software and solutions.

Some cool things I have been playing with:

  • Virtualization (SR-IOV, VT-D, VT-X)
  • Hardware RAID

These capabilities have been around for a while but mainly with servers. And they now arent even necessarily limited to servers since some high end desktops are now hitting 6-8 cores.

My Initial Problem:

Because I like to tinker around with a lot of different things, I pretty much needed a computer to fill each individual specialized task. This began to get pretty rediculous after a while. So many power cables, network cables, monitors, spare parts lying around everywhere. It became very unsightly. And not even to mention that each computer could consume somewhere between 20-100W idle. There had to be a better way!

Sure enough there is. It is called VMware ESXi, and it is awesome. I really wish I would have found it earlier. Vmware ESXi (Do they call it Vsphere now) is a bare metal Virtual Machine Hypervisor. It allows you to take a system''s hardware and divide its hardware resources up among one or more "virtual" machines. There are other products that do similar things, such as VMWare workstation and Virtualbox, but these are not bare metal hypervisors. They run on top of a given OS and tend to not be as flexible or efficient (but still very useful in certain circumstances).

So my server is HP ProLiant DL380 Gen9 with two processors with tens of gigabytes of RAM. I have multiple virtual machines set up off all different kinds of OSs depending on its purpose. Most are headless (I VNC/RDP into them) bit 2 are "headed".

Server Hypervisor

Table Project

Submitted by Matt on Tue, 12/23/2014 - 15:39

I have just finished a project where my Wife and I built a dining room table. All for about $120 in supplies, and another $100 in tools that I did not already have. 

Text CAD

Inspiration for the project came from an article on this site:


I modified the design a little bit to better suit our needs. I utilized Sketchup for the CAD design of the top.  The results were pretty amazing.  I still need to do chairs and a bench. But the bulk of the work is done.

Table Top View

Table Side View

And finally, some action shots

Katherine with materials

Burn Finish

Another CAD output




Submitted by Matt on Sat, 12/06/2014 - 15:20

A few years ago I started working on a little game I have come to call SpaceAge.

Space Age Screenshot
It was meant to be an amalgam of what I perceived to be the best elements of Eve Online, X2 The Threat, Freelancer and Dwarf Fortress. I wanted to create a massive and immersive world that was capable of showing the capabilities of cool AI stuff using the really powerful CPUs we have today.

I wanted:
- An artificial economy that truly was self-sustaining and that the user could influence. NPCs would be smart enough to exploit trade routes, setup new stations, colonize new worlds, and innovate spaceship production
- A procedurally generated universe the size of at least our local star cluster.
- Dynamic factions/races and changing political landscapes.
- Realism in as many ways as possible, based on humanity’s current and anticipated space exploration
- Detail on some level down to at least 0.2 AU

I chose to write it in C# due to my familiarity with it and the ease it is to singlehandedly implement large ideas quickly. I wanted to make the universe as realistic as possible, so I did some research to find out what the theoretical concentration of stars/systems is in our galaxy. I also researched economic models and aspects of theoretical physics and orbital mechanics. For the first few weeks the implementation got pretty far and was fairly pleased with the inner workings. But outwardly felt like you were playing with Excel.

XBee Wireless Switch

Submitted by Matt on Sun, 05/06/2012 - 15:39

When I lived at home for a summer, I needed a way to open our new gate because I did not have a clicker.

XBee Remote Tranceiver
XBee Tranceiver Switch

My solution was to use an Atmel ATMega 328p, some BJTs, a Xbee module to solve the problem.

Picture above is not the finished product, just the breadboard layout. I will try and add a picture of my proto board next time I see it.

The xbee connected to the home wifi. A very simple Androud app would sent a TCP packet to either open or close the gate. The signal would be relayed from the xbee over a 9600 baud serial line to the AVR, and then fire the BJT to complete the switch circuit.

As you may know BJTs are current controlled devices. I used them like switches here and it worked just fine. You just saturate the base with a voltage and the collector emitter current opens up. Fortunately a 5V GPIO from the AVR worked well enough to complete the gate switch circuit and open the gate.

Source is attached

Senior Design Project (UGSV)

Submitted by Matt on Thu, 12/01/2011 - 15:27

Attached is a document detailing our final report on the Unmanned Ground Surveillance Vehicle (UGSV).

Breadboard Senior Design
Breadboard version of our senior design project

I was the group leader of this project.
If you would like more info, please contact me. I am trying to find the original source code,  it is on a backup somewhere in my stack of drives. I will post it here once I find it.

See it in action in our corny youtube video here: