I recently purchased a USB mug warmer off of ebay.  It was one of the $2 ones, with integrated 4 port USB hub.  It shipped in from Hong Kong.

At first, I found it fantastic.  It seemed a great use of USB to me.  I often consume warm beverages at my computer, but I usually don’t finish them before they get cold. Unfortunately, reality soon sunk in.  The warmer just didn’t keep things warm.  It barely got warm to the touch.

So, I dissasembled it.  Taking a look at it, it was nothing more then a simple hub with an added resistor circuit on a switch.  The resistors simply dissipated voltage when the switch was thrown.

So, the first “increase the heat” modification was to disable the USB hub that was robbing voltage from the heating element.  I cut a trace on the board by scratching it with a screwdriver.  No more hub voltage.  But alas, even without the drain of the 4 port hub, it scarecly got any warmer.

I set aside the “heatsync” (a 1/8th inch thick piece of aluminum about the size of the bottom of a coffee mug) and let the resistors heat up on their own.  After a 10 minute heatup…they got kinda warm.  So, I deduced the resistors weren’t making good enough contact with the heatplate.  I removed the globs of thermal paste, added a little back, and put a penny between each resistor and the plate.  EUREKA…heat….but only in two very small spots.  The resistors just didnt have the oomph to even begin to heat the plate up.

So, I decided to do some math.  Ohms law to the rescue.

I = V / R

I being current in Amps, V being voltage in volts, and R being resistance in Ohms.

and

P = V x R

P being power in watts, V being voltage in volts, and I be resistance in Ohms.

After scraping off all of the thermal paste, I discovered that the resistors were 17 ohms.  The two in series was 34 ohms of resistance.  After some math, I found out that they were dissipating .73 watts of power.  This is NOT a lot of heat.  So, it was time for a drastic redesign.

I came up with this circuit.

All of the resistors in that circuit are 1 ohm, 1 watt resistors.  The total resistance of that circuit is 10.5 ohms.  Using the above formulas, that circuit would dissipate 476 mA of energy, less then the 500 mA possible from a USB port.  It also would dissipate 2.38 watts of energy, producing a nice, toasty plate.

All of the parts have been ordered and are on the way.  I’ll soon be posting photos of the build process and an instructable.  I’ve already decided to use the housing from my current warmer, removing the built in circuit and adding to some mass to the warmer plate.

4 port usb hub, Amps, circuit, EUREKA, Hong Kong, R I, R P, resistor circuit, USB, V Hide

Sadly, my trusty laptop didn’t survive the most recent move in my life.  Well, she kinda did….kinda.  She had 3-5 dead pixels in the top right corner of her screen.  This didnt bother me that much, and I let it slide…hoping it wouldn’t ever get worse…I was wrong.  I opened her up recently….big nasty black patch in the upper right corner.  Laptop rendered unusable.  First though was repair her..but due to her tablet nature, no one sells screens.  Well, with over 2k into her, I cant just trash her…hrrm…

A dilema in my nerdhouse as of late has been power consumption.  My nerdmate and I both have fairl beefy computer setups, with multiple LCDs to boot.  We’re pulling A LOT of juice down leaving the monsters on.  Why are we leaving them on?  Well, I am running torrents (100% LEGAL ones FYI!) and she..well…I dunno, just likes burning down rainforests to leave her computer on.  So I needed a low power solution to run my LEGAL torrents, as well as a few other tasks that I typically leave my PC on for.  Hrrm, my laptop uses VERY little power…hrrm..

Enter…the zombie server!  The laptop has risen from the dead to serve her purpose as a server!

Why did I want a home server?  Well besides the afforementioned torrents, I want to run a home media jukebox as well as other various and sundry things.

So, a brief how’d-he-do-it for now, a more detailed how to later.

• Installed a new OS ->Tried Fedora 11…failed with the hardware.  Ubuntu 9.04 works a treat.
• Installed a LAMP suit – Thats Linux Apache MySql PHP for the uninitiated out there
• Setup a firewall – Iptables, good stuff
• Setup some port forwarding
• Setup Dyndns.

Portforwarding AND a firewall?  Ubuntu as a server? ACCK!  Yes…I hear and feel your complaints a brewing.  Do not fret, because…well…I dont really care cause it works for me and I feel all cool and safe and stuff.  Feel free to do it your way!

For those that are happy with my way, look out for a howto in the next couple of days that will make you all silly happy with homeserver joy.

Fedora, firewall iptables, I, laptop, server, trusty laptop Hide

The internet is full of silly photos and videos of cats.  Why shouldn’t my blog be as well?

I consider the above video the absolute best reason to have a cat.  Not companionship, not rodent removal..nope..their desire to jump into boxes way too small for them.  Over the course of my life, I have been owner of and lived with a multitude of felines in varying genders and breeds…every single one has performed this behavior.  Im no cat behaviorologist so I wont even begin to try to describe why it happens.  I will simply let you enjoy the video and realize it is even more hilarious in real life.

Ahh cats…nature’s comedic relief valve.  If you’ll excuse me, I’m off to put and empty soda box on the floor and watch my cat chase it around.

cat, empty soda, soda box, video Hide