Stupid mistakes

I’ve been quite non-existent the past couple weeks.  Undoubtedly because of two things.  (1)  I have no internet at home.  The person whose wifi I’ve been using must have left for the summer.  Hence, I have no signal at home.  With three months left in Michigan(!), I don’t care.  It’s obvious that I’ve become a product of the ‘information age.’  What did I do before the internet?  Ah yes.  Read.    (2)  Because I only have a couple months left, I’ve been working ridiculous hours, hoping to finish this experiment before leaving.  12+ hours for the past few weeks is not fun.  (sometimes, it’s 15 or 16 hours).  Additionally, Dan—the senior grad student on my project—just defended his thesis, and will be leaving the lab shortly.  That means I’ll be in charge of this project, and I don’t know what I’m doing.

And things are not peachy in the lab.  We have a new student on my project, and I have to explain everything all over again.  We have very little power in our Raman laser, and Yisa just chipped the BBO crystal today (which is extremely expensive).  He’s too cavalier with optics.  But I figured out why I was only getting ~90% qubit detection fidelity—apparently some idiot turned off the RF generator for the doppler cooling beam.  Thus, we weren’t cooling the ions.  Alas, the initialization beam got mis-aligned.  The fun never ends. 

It’s official: I’m an EE

A month ago, I inherited a stereo receiver/amplifier from Karyna. She got it from Craigslist, and it was starting to ‘go bad’—some crackling, and other non-niceties in the sound. She got a new amplifier from her parents, and decided to give me this one. As for what I’d do with it, I’m not too sure.

So I ordered a service manual from stereomanuals.com. Despite their horrendous website and slightly cryptic e-mails, I managed to get the right service manual. And it is beautiful. They do a bang-up job on reproducing the manual, and they are rather prompt in shipping. So, I highly recommend them—in spite of their horrible website.

Now, I’m looking at the circuit layout, the block diagram, and everything; thinking to myself: damn, that’s complicated, but I could make that! It’s obvious now that I’m ‘in love’ with circuits. I have a specific task that’s interesting to me, and I am thinking about how to build it.

Anyways, I need to spend some time with my receiver/amplifier and figure out what’s wrong. By looking at the block diagram, I’ve realized that I can cut out 90% of the circuit, as it is obvious it has nothing to do with what’s wrong.

Electronics!

Even though I was an Electrical Engineer, I never was one for electronics.  But since I’ve been in a lab, and needing it to run experiments, I’ve become a recent convert.  I blame Cornell’s ECE 210/215.  Those classes (when I took them) were more about “what’s the voltage here” and “the current there,” rather than developing electronics to do things.

For example, in this lab, I needed a PID controller for Laser frequency stabilization.  Basically, the frequency of the laser drifts, and we need to control it, using a feedback loop.  Basically, the PID controller adds a correction to the current in the laser diode (which determines the frequency of the laser) .  This correction is a sum of a proportional signal (i.e. what’s going on right now—are we too high? or too low?), an integral signal (in the long-term, what’s its tendency to do?), and a derivative signal (right now, are we drifting away from where want to be? or towards?).

This provides an actual purpose to the circuit.  Can I build a proportional signal?—yes, that’s just an amplifier with adjustable gain.  I can build an integrating circuit, and a differentiating circuit as well.  But before, I never had any reason to build them.  They were just simple circuits that did what they did, and that was that.

That’s what was missing in my intro circuits class.  I never felt that the circuits we made were to do things.  We made circuits, and tested to see how they behaved.  Which, quite frankly, didn’t interest me at all.