We just had some t-shirts printed with the Octopart logo on the front and the gear on the back. They are really comfortable and we try each one of them on before giving them away. If you want a (free) t-shirt just email me and I'll send you one. Check for prices and availability by searching for "octopart t-shirt".

working on cool hardware? submit blogs to contact@octopart.com

There were two design requirements I started the project with:

1) Each listener needed an independent amplifier channel.

2) The whole thing had to fit in an Altoids tin.

It works like this: plug your ipod or DVD player into the jack on the left side of the case with a male-male 1/8" audio jack. Headphones go into either of the two output jacks in the front of the case. Each knob acts as a combined on-off switch and volume control.

The design is based on a non-inverting op-amp circuit inspired by Chu Moy's original Cmoy headphone amp. The op-amps are Burr-Brown OPA2134PA which sound GREAT. You might wonder, "Why not just use a headphone splitter?" Well, that halves the power delivered to each set of headphones and sounds lousy. Also, if the listeners prefer different volumes you're stuck. This amp can drive big fancy headphones REALLY loud with very little distortion.

Back when I started this project I thought I would get a bunch of PCBs printed and start a little business selling the built amplifiers online. I sold about 15 before I had enough of the solder fumes and got tired of eating altoids and called it quits. I still have the PCB schematics and few unused PCBs. I'm rebranding it as the Octopart Doublet Amplifier. I'll go into more depth about the design and part list in my next blog post. If anyone is interested in the leftover PCBs, let me know. When you buy the parts to stuff them, just let the distributors know that Octopart sent you.

Part 2: Schematic, Parts List and PCB

Like many particle physics experiments, ATLAS is a collection of several concentric cylinders, each cylinder being a different detector technology. At the center of all the cylinders two very high energy beams of protons are brought into collision; it's then the job of the different detectors to give some clue as to what just happened by measuring the trajectories of the particles that were produced. The inner cylinders can make very precise measurements of where a particle crosses it, but are also very expensive to build per unit area. The outer cylinders are cheaper per unit area to build, but not as precise. The pixel detector - what I work on - is the inner most layer. It's taken many hundreds of man years to get to where we are now, and all for an active area of less than 1 1/2 square meters. But the upshot is that it will be able to measure track vertices - meaning where the different particles were produced - with an accuracy of a hundred microns, or about the width of a human hair. And it can do that for thousands of tracks every 40 million times a second, all the while operating in an intense radiation field for years.

Here's how it works: each module (about size of a booklet of postage stamps; see the diagram) starts from a 15mm by 60mm piece of very high purity silicon. The silicon is divided into a grid of 48,000 little rectangles, each rectangle containing, among other things, a p/n junction diode. Then 16 integrated circuits are laid down underneath the sensor silicon. These ICs amplify and digitize the charge pulses that get created when a charged particle passes through one of the sensor diodes. Then, a 2nd type of integrated circuit - the MCC, for module control chip - collects all of the information coming from the 16 front end chips and communicates the results to 300 or so custom read-out drivers in the 'outside world'; meaning outside of the detector volume of the all the other subsystems.

The final detector is made up of almost 2000 modules, arranged on a graphite frame. Then the tricky part of snaking the low voltage cables, high voltage cables and cooling fluid pipes through the outer cylinders begins! And of course, this is to say nothing of how one actually makes sense of the data once it's on disk.

So where are we now? The final module design has been finalized for several years and the manufacturing and testing of the modules has been completed for almost a year. In that time, the modules have been loaded onto their mechanical frame and permanently connected to the first series of patch panels that provide service support for the system. In December, an attempt to run 10% of the system simultaneously was successfully completed. Final tests of the connections to the patch panels mentioned above were just completed about 1 week ago; the current plan is to lower and insert the detector inside the other layers before the end of this month. After that, it's still a lengthy road, but we hope to have the entire detector cabled and ready to read-out (still uncalibrated) by the end of year.

working on cool hardware? submit blogs to contact@octopart.com

Today we added an auto-suggest feature to the search on Octopart. I'm particularly proud of this one, not because I think it'll be particularly useful (you'll be the judge of that - e-mail me with comments and complaints), but because its the first piece of code I've written for Octopart while living a healthy balanced life.

Let me rewind a few months. While in grad school, I ran about five miles every other day and spent another three hours a week in the gym. Working out lets you achieve small measurable goals, something I craved after long, fruitless days in the lab. Plus, I took just about any excuse I could to get out of the basement for a little while. I was in the best shape of my life.

A few months before joining Octopart, I started working on a separate website. Since then, I've been a man obsessed. Coding became my way of relaxing and taking breaks from the lab. Joining Octopart full-time amounted to a ten year old being let loose in a toy store. My daily exercise regime dwindled down to the walk up the street every morning to get a coffee. Food quickly became the sole sensory pleasure in my life. In just five months I turned from someone with marathon-running aspirations to someone who prayed every day that he wouldn't have to buy a new pair of jeans to accomodate a burgeoning waistline.

I'm happy to say that I'm finally learning how to live a balanced life. Andres and I have been going on daily runs and cooking one meal a day - we even had leftovers the other day for lunch. I'm feeling sexier by the day.