Wednesday: more circuits

Though we are a little behind where I imagined we would be, we are ahead of where we have to be, so we'll spend the rest of the week learning how to build and analyze more complex circuits. We're almost far enough that I can let you design your own projects ...

Wednesday, we'll re-hash what we know of transistors and learn how to build a basic amplifier (on paper, for now) [slides I'll use]. We'll then focus our attention on comparators, a simple-yet-powerful device that compares two input voltages. This will serve as an introduction to feedback and basic logic circuits, which will let us build all sorts of neat things.  Such as a relaxation oscillator, which you will actually build in the lab [circuit]. We'll use it to make an LED blink periodically without any code at all. So far as circuits go, we only need to know about a few more components (inductors and op-amps primarily) before I'll just start turning you loose on projects.

Next week, we'll move on to magnetism and magnetic fields, which means back to more abstract things for a while. Lab-wise, next week we'll try to learn a bit more about coding for the Arduino. Once you have a bit of software knowledge to go with your hardware knowledge, we can do very neat things. You should start looking at some possible projects.

Today's slides

Here are the slides I used today [7Mb PDF], and a bunch I didn't use yet. Course information, contact info, and the vector stuff I talked about.

dc circuits slides / lab circuits

You can find all that stuff here:

http://faculty.mint.ua.edu/~pleclair/ph126/

Go to the "Media" directory for the circuits slides I've been using, and go into the "Labs" directory for images of the circuits we're building.

From time to time, other goodies will be deposited there as well. (I drew all the pictures and wrote all the text, so consider all this stuff to be freely distributable.)

Today's circuit slides / oral exam

Here's what I presented today, along with some stuff we'll get to next time. Powerpoint format, I'll try and make a PDF later today just in case.

Also: good work on the circuit today. I was very happy that everyone got it to work within the allotted time! Wednesday, we'll try to add an amplifier to the output stage (i.e., the voltage on the resistor you probed with the scope) to make the thing more sensitive.

Lastly, if you want to schedule an oral exam to improve your Exam I score, here are some time blocks that are good for me. I can meet you in Gallalee or Bevill, whichever is easier, but I'll list my preference.

Tues: 12-5 (Bevill preferred)
Wed: 1-2:30 (Gallalee preferred)
Thurs: 12-5 (Bevill preferred)
Fri: 10-11, 12-1 (Gallalee preferred)

If possible, I would like to do the oral exams this week, or this coming Monday at the latest.

Do not try this at home

Wow. Relax and get some sleep before the exam.

Feynman lectures & videos

In case you missed it, this comment is worth a read, from the editor of the Feynman Lectures on Physics. Yay internet!

Also, you should really check out the video lectures by Feynman himself, made available to the public by a very generous gift from Bill Gates. These are lectures from 1964 at Cornell, and were not really available to anyone until Mr. Gates took it upon himself to make it possible. Many of the lectures tie in to the Feynman Lectures textbook, and are well worth checking out.

No matter how you feel about his software, the man has done physics a solid ...

Equipotentials of a charged rod

Here are three of them, just for fun.

Slides from the first lecture / schedule

I've uploaded the slides [~6Mb PDF] that Prof. Harrell will be using for the first lecture, which is mainly a course overview and a math review.

Prof. Harrell will (probably) go through all of this material, I'll pick up where he left off on Monday 24 Aug and we'll go further into derivatives of vector fields. Wednesday 26 Aug, we'll go through integration over vector fields (line integrals) and start doing some actual E&M.

Don't worry too much if the math seems frightening during the first few lectures. After our brief tour of vector calculus, the math will get less scary again. The quick overview in the beginning is meant to give you an idea of what we'll need during the semester, and as these topics come up in real situations, we will review them in more detail at a slower pace. Any math that is not part of a prerequisite course I will cover in class, and I will try hard to bridge any gaps between our textbook and what is covered in, e.g., Cal II.