a place for bandits

Voltage Division with coarse and fine adjust

2011-04-30T09:42:00.000-07:00

In designing the Voltage source of the last post, I originally wanted to have 2 adjustment knobs, one coarse and one fine. I concidered designs using two linear potentiometers but the fine adjustment wasn't as I wanted it to be. I wanted it to always provide a uniform range +- around the coarse setting ( I call this +- range delta V). It didn't provide this, instead it would give a large delta V when the coarse was set at one extreme and zero delta V at the other. Circuits A and B below demonstrate this effect.
I then discovered that by using a standard linear pot for the coarse adjustment and a dual gang linear pot for the fine adjustment my desire could be accomplished as represented in Circuit C.

Equations for Vout/Vin for the three circuits and corresponding plots with R1=5k, R2=100k, R3=20k are shown below. I've introduced variables x and y to represent the fraction of R2 and R3 which are enabled by the pot knob and can take values from 0 to 1. The plots show the extremes of the fine pot (y=0, y=1) for all values of x. The size of delta V can be set primarily with the value of R3. I do like this design but didn't end up using it because I was impatient and didn't have immediate acces to 5k dual gang pot. Maybe next time!

Variable DC Voltage Source

2011-04-19T04:25:00.000-07:00

I wanted to have a DC voltage source for home projects and I decided to make one. I cheated and used a "wall wart" transformer which I picked up at the Goodwill. This takes care of AC step down transformer and rectification, I ended up adding a number of components though to protect from voltage spikes, smooth out the voltage, reduce noise and buffer the output so the load impedance has minimal effect on the voltage setting. The 100k pot sets the voltage output but there is a switch which can select between a 0 to 20V output range and a 0 to 10V output range which gives a little more control in the lower voltages.

I breadboarded most of the circuit before soldering to perf board, it seems to be working well so far but I am waiting for the analog panel meter (one of those old ones with a needle indicator) and I still need to find a nice little box to enclose it in.

This is a low current supply, I may build another one very similar but with a heavy duty 25V transformer that I have sitting around. We'll see how this Goodwill special holds up.

Preliminary Experiments With BJTs

2011-03-29T11:02:00.000-07:00

I've just begun to experiment with bipolar transistor amplifier configurations powered by a 9V battery and this circuit gave an interesting clipped sound. I also made one that gave a clean boost but that's not as interesting to listen to. The output of the circuit was fed into a Roland keyboard amplifier. Interestingly (and a little sadly) when I got out the guitar to test this it was the first time I had touched it in months. The next circuit I tried had high current through one branch and it fried a pnp device in about ten seconds! I'll have to put my experiments aside for a while because of a heavy school load, lots of boring school assignments to finish this week.

Setting Up Shop

2011-03-26T00:02:00.000-07:00

These are my new lab partners: Sophie, Shazer, Shule and Sally.
They are helping me set up an electronics lab at the house. My only piece of test equipment is a handheld digital multimeter but I've started designing a simple DC Voltage source which I've been collecting some components for. After building that I will make a preamp for a ribbon mic I have.

I just got way too busy to keep up with the circuit of the day postings, in place of that I'll start updating how my projects are going. School has been busy, I've found out that layout can be very time consuming but also I've been distracted by planning my own side projects, which I'm getting very interested in. Here's to playing safely with electricity!

Day 9: ESD Protection Diodes

2011-02-28T17:20:00.000-08:00

I took the weekend off but we're back today. My schedule may prevent me from posting daily but I'll keep putting things up when I have time. Today I look at something that I've seen quite a bit as an intern in the protection division at ON Semi.

Day 8: Ideal Op-Amp with Negative Feedback

2011-02-26T01:09:00.000-08:00

For stability and to avoid riding the rails (clipping at the op-amp +-Vcc), the feedback path impedance must not be allowed to become too large.

Day 7: PMOS Current Mirror

2011-02-25T07:31:00.000-08:00

Day 6: Wheatstone Bridge

2011-02-23T20:13:00.000-08:00

This question was asked in a written test in a job interview last week.

Day 5: Diode Bridge Rectifier

2011-02-22T21:28:00.000-08:00

I love how simple yet so genius this configuration is. So many things we plug into the wall have this in it; there must be zillions of these out there.

Day 4: Damping, 2nd Order Systems

2011-02-21T22:27:00.000-08:00

Continuation of yesterday's circuit.

Day 3: Series RLC filter, Band Pass

2011-02-20T14:07:00.000-08:00

Day 2: RC LPF #2

2011-02-19T00:13:00.000-08:00

Adding a shunt resistor parallel with the cap in the RC LPF reduces gain but increases bandwidth.

Day 1: A Circuit a Day. RC LPF #1

2011-02-18T23:10:00.000-08:00

I don't expect to keep this up long. Way too busy for that, but I've been trying to refresh my knowledge from old courses due to recent job interviews and the upcoming FE exam. Sorry to be so esoteric for all you non-circuit types (most people). It has been nice this semester to get back into circuits; I don't see myself extensively studying semiconductor physics any further. I've been wrong before though!

Musical Note Frequencies

2010-08-23T23:28:00.000-07:00

I was thinking about how doubling the frequency of a note gives you a note one octave higher. Case in point: A 220Hz--> A440Hz, contrast this with the next octave A 440Hz --> A 880Hz and we see that the span (in Hz) of each successive octave is greater than the previous. The frequency of ascending notes has an exponential relationship that goes like 2^x. I was specifically thinking about this because the only musical note and corresponding frequency I knew was A440Hz and I wanted to know the frequency of any note I could think of. Knowing this single reference frequency and the fact stated in the first sentence of this post I found a formula that will tell the frequency of any note, I figured I would reference the formula to the 88 keys of the piano for convenience where n=1 is the lowest note and n=88 is the highest.

This graph of the above formula shows the exponential curve nicely and I've added the piano keyboard as the x-axis which corresponds to the domain of the function, integers 1 through 88. I have no immediate use for this information but I just feel better knowing that I now have an easy way to know the frequency of all the notes in western music. The formula actually works for n values less than 1 and above 88 but those probably won't get used too much.

One last thing I wanted to incorporate before I could rest was the phenomenon familiar to piano tuners called "stretch". It so happens that there is inharmonicity in pianos, especially in smaller scale and poorer made pianos but even to some extent in the finest pianos ever made. One result of this inharmonicity is that harmonics (overtones) will occur not perfectly at integer multiples of the fundamental frequency. This causes some notes to sound bad in the extreme ranges of the piano when the string is theoretically in tune to the frequencies in my little formula above. Stretching the notes sharp in the treble and flat in the bass is typically done to compensate. Additionally, I think we like to hear the high notes a little on top of the pitch anyway just to avoid the appearance of being flat. The amount of stretch depends on the piano and the mood of the piano tuner during the tuning. I have modified the formula to accommodate stretch. The .1 value can be increased or decreased for more or less stretch. All in all I think it's a decent model.

Many Changesfor Summer 2010

2010-06-01T12:08:00.000-07:00

We have moved, it's about a 5 mile drive south west of our old location. The new house offers more space, a garage, a backyard area, a friendly neighborhood with schools and a great park nearby. We are glad to be leaving the old apartment, I've lived there longer than anywhere else second to the Rosewood house. I think everyone in the family is taking to the new house quite well.

I also started working as an intern at ON Semiconductor in the protection group which handles parts designed to protect devices mostly from electro static discharge; you don't want to kill your cell phone or laptop because you rubbed your feet on the carpet a little too much. Within the protection group I will be working with Zener diodes and TVS arrays. I am very happy about this opportunity and I believe it should set me up to be more employable come next summer when I will have graduated. This summer internship could extend into the fall semester, we will have to wait and see.

Now the bad news, we had a transmission failure in our van! I guess the '98-'01 model Odyssey doesn't have the best transmission. It will be out of the shop Wednesday and will be paid for with the help from some insurance money from our burglary incident which happened 4 weeks ago for those who hadn't heard.

All in all, things are going along pretty well I suppose. I'm sure pictures of summer activities with the kids will follow.

Digital Frequency, Sampling a Sinusoid

2010-03-22T18:00:00.000-07:00

I am preparing for an exam in DSP (EEE 404 at ASU) and I've been confused about digital frequency. It seems like a simple enough concept but I've been getting it mixed up. So as I sort it out I decided to blog it for my benefit and because I can't seem to find many examples. If I can post a decent blog about it then I figure I'm at a point where I understand it so here it goes.
Initially I learned to use a lowercase omega for angular frequency and a lowercase f for frequency (Hz). Then in this class they use capital omega for analog angular frequency, capital F for analog frequency, lowercase omega for digital angular frequency and lowercase f for digital frequency. This little symbol change has tripped me up. I wrote out the basics to help me keep it all straight:Note that n in the above example is restricted to integer values. Now that I have all that down it should be the easiest part of the test, but let's think about the meaning of digital frequency: I believe it can be thought of as the fraction of the continuous signal's cycle that is represented by a single sample. I say fraction because if you follow Nyquist's Sampling Theorem for signal recovery (simpler explanation of Nyquist theorem here), your sampling frequency should be at least twice the frequency of the signal frequency and noting that digital frequency is the ratio of frequency to sampling frequency it is evident that digital frequency will be less than 0.5. It is possible to neglect the sampling theorem and doing so shines the light upon an important difference between discrete samples of sinusoids and their continuous counterparts: For a sampled signal with f greater than 0.5 there exists a signal with f less than 0.5 which is the same!
In the next example I have sampled a continuous signal at two different frequencies, the first with f greater than 0.5 and the second with f less than 0.5. The continuous signal is with light dashed lines and the discrete samples are bold impulses, they share the same plot (the horizontal axis thus represents both t and n). Notice that the first set of discrete points suggests a sinusoid of a lower frequency (namely 1/4th of the original frequency) and therein lies the danger in having your sampling frequency too small.I think I've got a pretty good handle on this, now I need to study all the other stuff that may be on this exam.

a few items of interest

2010-01-21T15:52:00.000-08:00

What a great deal. Century Gateway 12 really came through for me on this one. I'm not a big movie-goer, when I go I like it to be really good and not just mildly entertaining. This movie was really good.

in other news:
I have 2 songs I have been working on recording, they are in fact mostly finished. They have drum, bass, guitar and other instrumental and even backup vocal tracks done but they both lack the lead vocals. I hope I can finish them before school starts to get busy. There's not a lot riding on it I know but if I can finish these recordings off soon I think I would be able to wholly focus on school and be a good student.

People have gotten colds and coughs at our house, Shule went in a few days ago for some shots, I've been doing more dishes by hand lately because I'm dissatisfied with the work our machine has been producing. Our little girls have been growing and doing active little kid things that make it hard to keep the house in order, but we've been doing our best to keep up. I have been applying for internships and looking more seriously into post school options.

That's what's going on and I'm not really inspired to put it all into a flowing blog post with clever anecdotes, but for what it's worth, I just wanted to get it down anyway.

Towards Mid-Junior Year

2009-11-16T16:42:00.000-08:00

The end of the semester is in sight. Unfortunately the Thanksgiving holiday is right in the middle of some major lab assignments so I have to see that I get those mostly completed this week even though they aren't due till after holiday.

A brief overview of this semester's studies:
The circuits class has consisted of op-amps, diodes, and MOSFETs. Still to come is a section on BJTs. The lecture is great but the lab has been a huge amount of work. We still have 2 more lab assignments to do and they are very involved.

This semester's signals class was not so enlightening as last semester's but still good. Topics included sampling, modulation and transmission (mostly AM), feedback systems and root locus analysis. The LabView assignments aren't particularly exciting for me but hopefully I'm learning something.

My affection for VHDL seems to oscillate between positive and negative. I have been excited about it and hated it but right now I'm feeling pretty good about it. I like working with VHDL more than with software programming languages.

Random Signal Analysis, hasn't had much to do with signals at all yet. It's an introduction to discrete and continuous random variables regarding probablility, expectation and variance.

As I go into my last 3 semesters I plan on taking 3 more circuits courses, digital signal processing along with another signals course on filter design or some such, and properties of electronic materials. Oh yeah, next semester I have to take economics too, maybe it will be enlightening.

jellybeans

2009-09-28T17:16:00.001-07:00

I've been stumped on this problem all weekend:

A candy factory has an endless supply of red, orange, yellow, green, blue, and violet jelly beans. The factory packages the jelly beans into jars of 100 jelly beans each. One possible color distribution, for example, is a jar of 58 red, 22 yellow, and 20 green jelly beans. As a marketing gimmick, the factory guarantees that no two jars have the same color distribution. What is the maximum number of jars the factory can produce? (Hint: Think of lining up the jelly beans, by first placing the red ones, then the orange ones, etc. You also place 5 dividers to indicate where one color ends and another starts. Note that two dividers can be adjacent if there are no jelly beans of some color.)

What do you think?

The Story of a Trombone (the wonders of steel wool)

2009-08-25T23:20:00.000-07:00

Twelve years ago my sister-in-law Brenda, knowing that I was very interested in musical instruments of all sorts, gave me a trombone that she had played in high school. This trombone was in a fire and had suffered major cosmetic damage in addition to the case being destroyed and the mouthpiece lost; the thing was ugly.

In an attempt to make it more presentable, I put it in the bathtub and tried to scrub the scum off; soap and water did nothing. After giving up on making it look better, I turned my focus to how it sounds. I got a mouthpiece for it and I even lucked out by getting a free case. The case, while a little bit used and shabby, looked like a dream compared to what it protected. After just a little bit of maintenance the instrument worked just fine and I proceeded to learn how to play it for a few months as a curiosity.

After a little while, it got tucked away in a corner and there it waited for many years until this year because Shule has decided to join the middle school band. Over the summer, Shule and his band director decided that he would start on the trombone. Marisa overruled my idea to send him off to school with something that looked like it was just pulled out of a landfill. She's totally right too, I fell in line quickly because in those awkward times of middle school, it may be best to not create extra opportunities for ridicule.

There was talk of renting or buying an instrument but I was developing an idea to avoid that if possible. When I came home with steel wool and a smile on my face Marisa gave me a look as if to say: "I'll humor you for a little while, but if this doesn't work we're going back to the original plan".

The finish on that trombone was cooked and in many places it was charred not just on the surface but deep into it. I worked on it for 3 days and my hands ended up sore and discolored but it worked. While I was at it I smoothed out some of the dings.

This shot was taken halfway through the process for comparison. Notice how good the bell looks next to the unfinished slide.

I can't say it looks new, but it looks like an instrument that's been used and cared for. This definitely beats buying or renting one, most rentals probably don't look this good. Since I've invested some toil, I've developed a new attachment to it and Shule is even happy to announce: "my trombone has survived a fire!".

A car trip

2009-06-27T09:18:00.000-07:00

but Shule stayed awake.

Renaissance Festival

2009-04-14T19:55:00.000-07:00

Shazer won some tickets to the renaissance festival a few months ago. We finally used them Saturday March 28th. I took Shule and Shazer, it was the first time for all of us. We walked around a lot and saw a lot of shows, including: pipers and drums, humorous clowns, jugglers, a whip cracker, a large fowl show (falcons, owls and vultures), and jousting. Along with the numerous shows there was ample opportunity to spend a lot of money on all manner of crafts, clothing and food. We just window shopped as we walked around the park in between shows. A few things that stand out from wandering around the market were the ladies spinning wool into yarn, weaving fancy tapestries and the blacksmith with a very impressive bellows stoking a very hot fire. The boys had a good time, Shazer especially is interested in the sword fighting element so he was excited to see the dramatic jousting presentations (see video below). Shule liked the jokes that the jugglers told. He got tired but I convinced him we should stay longer and we would get to see some interesting things that we wouldn't see anywhere else. He stuck it out. Please view the full web photo album.

light is a bandit

2009-03-30T17:18:00.000-07:00

I've started learning about special relativity in school. I've heard a little about relativity in the past and had previously developed a sort of blind trust that space and time are relative to frame of reference, or something like that. I knew that if you go really fast then time doesn't pass at the same rate, I had no clue how. Recently when working with optics I read that light travels away from the source at a constant speed and even if you were moving away from the source, as far as you are concerned, the light still approaches you at the same speed. This concept totally blew my mind because as you all know: when someone throws a ball at you and you run away, it then appears to you that the ball is coming at you slower than if you just stood still. If the ball behaved as light does then as soon as you start running it would speed up to its initial speed plus your speed. So how is light an exception to the laws of mechanics? Maybe it has something to do with light being a wave of energy stored in electric and magnetic fields, also light has no mass like a ball does. It turns out that this curious behavior of light is Einstein's second postulate of special relativity and because of it, crazy things happen. Things I don't yet understand so I won't try to explain.

I do however want to share what I think is an interesting example of current in a wire from 2 different inertial frames of reference. We have observer 1 who is stationary with respect to the current and observer 2 who is moving with the same direction and velocity as the current.

Observer 1 experiences a magnetic field (it can be calculated by Biot-Savart, or Ampere's Law).

If we imagine the current as individual positively charged particles then to observer 2 the so-called current becomes an electrostatic line of charge.

Observer 2 would experience an electric field due to these charges (we find this by Coulomb's or Gauss' Law). This might lead to a nasty disagreement between the two observers as observer 1 would insist that there was a magnetic field and observer 2 would be quite certain that it was actually an electric field and they both would be right. I must give credit to Gary Adams who showed that to me (and 170 other people in the room) last semester and is a really great physics professor.

Radio in my Head

2009-03-11T23:40:00.000-07:00

Introductory note: If you are not a very big Radiohead fan I don't expect you to explore all the links in this post but please if you do anything, go here! (I'll remind you again at the end.)

I'm interested in how bands form, I like to read about how groups got started. It's an interesting thing that when I want to find out about a band, the first place I go is Wikipedia. I find that you get a good summary of historical information on groups whereas if you go to the artists official website you usually just get the latest news and things that don't interest me as much. I'm interested in the humble beginnings, the ugly past, the trials and failures gone through before the big break. Wikipedia will usually give you a good start but if you want to know more you have to search for in-depth interviews or maybe someone's put out a book on the band. I've been getting more into Radiohead lately and they have the most confusing official webpage of any band I've seen. None of it really makes sense to me and I can appreciate that maybe the band just wants to express themselves a certain way, they are entitled to it, I just don't get anything from visiting. Since their site left me unfulfilled I searched for content elsewhere and found it.

On youtube there are some videos of the band doing a sort of house concert videocast performance. Actually it looks like they did one on Nov 9 2007 and another Dec 31 2007. The former was entitled "Thumbs Down" and the latter "Scotch Mist". In fact, "Scotch Mist" is a 52 minute video available on youtube including performances of all the songs from their new album. These are live performances but the band is just set up in a house somewhere and the audience is on the other side of the podcast. I totally love it. The Thumbs Down session included them doing covers including The Smiths "Headmaster Ritual" and Joy Division "Ceremony" among others. So maybe you don't want to devote a few hours watching these videos, I understand that. You can also view individual tracks, Radiohead actually has a good youtube profile with some of the songs listed separately. (I just want to squeeze in another link the song there there, a really good video from a live concert).

Portishead also did a similar videocast just before the release of their newest album. The video is called "Portishead in Portishead" I believe. It was available till the release of the album but I've found that if you go to their official site you can register your email with them and they will allow you access to the video. This one was also captivating to me, I loved watching their New York live video, some musicians are just fascinating to watch. They do such interesting things with vintage keyboards and old tape echo effects.

I've been walking around with "Jigsaw Falling Into Place" in my head. It's on Radiohead's latest "In Rainbows" album. I learned the guitar part and fooled around with working the song up myself but I have the problem that my voice is not high enough. Makes me a little frustrated but I've encountered this frequently so I have a procedure: I consider falsetto, I consider transposing, I consider whether it just wasn't meant to be, I try harder to extend my range. The first 3 options have been successful enough to keep me content in the past but the last one still hasn't ever come through for me as well as I want it to. If I end up working it out I'll post a video and you can witness for yourself me trying to fake my way through it.

So in writing this post I have come across yet another set of wonderful performance videos for VH1 Live From The Basement. Much like the other videos mentioned but a little smoother around the edges and with a few different songs. I highly reccomend Where I End and You Begin, this is the link I mentioned at the top and you can see Jonny Greenwood playing the unique instrument the Ondes Martenot, you can play it similarly to a theremin. I've overloaded this post with links and I realize I've gotten out of hand so I'd better end it now. I hope there is music out there that gets you as excited as this gets me.

Pinewood Derby happy conclusion

2009-01-28T19:35:00.000-08:00

Just after submitting a school assignment that had been giving me anxiety for the past week, I rushed to put the wheels on the two cars and get to the race in time. I always think that the next year I will be ahead of schedule but I always end up finishing right before the race.

Shule ended up winning the race with his toad car driven by a pokemon! This is great because this is his last year so he went out with a bang. I was surprised to find that although Shazer's car didn't do too bad, it was not as close as I thought it would be to Shule's. I inspected it after the race and it turns out that there was a problem with one of Shazer's wheels, there was some glue involved in the final preparations and some got on the wheel. When we left the house I checked that the wheel was spinning freely but I guess the glue wasn't totally dry and in transit some must have seeped where it shouldn't have been. Considering this handicap, it did well and Shazer still has 2 more Derbies to look forward to. His sleek design won the "Most Dynamic" award.
You can see here that before painting, I masked the car around where the wheels go. I smooth this area and apply graphite because the back of the wheel rubs here.
Last night I put the weights in and smoothed out the wheels. I didn't have a scale so I used Shule's first car as a standard and I pieced together a balance with a ruler and a jar of paint.
This simple balance turned out to be quite accurate! When we got to the race the cars were right on and no adjustments were made. The race went quickly; there were only 11 cars this year. All the fuss has paid off and Shule will get a trophy next month at the Blue and Gold banquet.
This is a video of the winning race, look at the left side of the screen at the very end of the video, Shule and Shazer give each other a high five. That's the best part and I nearly missed it.

Physics of the Derby Bonus

2009-01-22T13:38:00.000-08:00

Here is a bonus post on my thoughts on the physics of a pinewood derby car rolling down the track.

There is really only one thing that makes the car move-gravity.
I drew a simplified diagram of the situation. I simplified the car to just a point mass. There are 3 forces on the car: mg- the force from the gravity of the earth, N- the normal force from contact with the track, and f- the frictional forces acting opposite the direction of travel.

The car only accelerates in the downhill direction of the track, I have designated this direction as the +x direction, which makes the normal force in the +y direction. The only force with a component in the direction of acceleration is mg, we can break it into x and y components to get a better look at what's going on.

Since the car doesn't move in the y direction we know that the magnitude of mg in the -y direction is equal to the magnitude of the normal force in the +y direction and those forces cancel.

We are now left with only x forces:

We want to sum these forces and set it equal to ma, or mass times acceleration by Newton's famous F=ma. So we watch our angles carefully and discover that the magnitude of mg in the x direction is mgsin theta.

The rolling frictional force from the wheels on the axle and wheels on the track can be represented with a constant k multiplied by the magnitude of the normal force which is the same as the y component of mg. If we assume that the race will take place in a vacuum then this is the only friction that we need to consider. This gives us an interesting result:

The acceleration of the car and thus how fast it will go down the track does not depend on the mass of the car! Reducing the friction of the wheels is the only thing you need to do to build a fast car. So why does everyone say that if you add weights to your car it will help you go fast?
Well, it might be that I have neglected important factors in my simplifications. I should put the race back in an air filled environment so the spectators don't have to bring their own oxygen. This will introduce another frictional force from the air but from what I've seen so far in my classes, this force has little effect in many cases and often times is neglected. Either we have in vain been putting weights on our cars for years or conventional wisdom is correct and air drag makes enough difference for us to bother with attaching weights.
It all depends on what the coefficient of friction is, which I believe involves the density of air and the shape and density of the car. This can be found experimentally. With that term added our expression now looks like this:

The force of the drag is proportional to velocity. This makes me very curious now and I want to get that track and do a bunch of tests with varying weights and other things to find out how much effect this really has.
The placement of the weight may have something to do with the stability of the car also, to figure all these things out I'd have to do a more complicated analysis and look at the car as something more than just a point mass. I'm not going to do this, and now that I think of it, the urge to do a bunch of tests is leaving me too. I'm feeling content enough to just get those wheels turning smoothly, put weights on the cars till they are 5 ounces and enjoy the race.
I would like your input on the matter though. If you happen to have any insight on these things please let me know, I'm sure I've missed something.

Pinewood Derby part 2, axles and wheels

2009-01-20T12:08:00.000-08:00

The nails that make the axles have a few bumps on them out of the box. To smooth them out I mount the pointed side of the nail in the end of a power drill leaving the whole surface that will contact the wheel exposed.

I spin the nail and first use a small file to get the bumps out.

That's just not going to be smooth enough for me though so I will then start using sandpaper, keep doing it over and over with a small strip of increasingly fine sandpaper.

If you look in the paint section of the hardware store you will find some pretty fine sandpaper. What I have is 600 grit wet sandpaper. I've heard of finer sandpaper but Home Depot didn't have any. This will give you a pretty smooth nail. I also like to make sure that the underside of the nail head is smooth, that area will also contact the wheel.

There is a theory that if less area of the axle comes in contact with the wheel it will spin faster so some people make grooves in the nail, reducing the area of the wheel in contact with the nail. I'm not convinced this does anything because friction depends on the mass of the car and the coeffecient of friction of the materials which are rubbing and it does not depend on the ammount of area in contact. If you reduce the area in contact, you also increase the load per unit area so it all evens out. Another "myth" that I've seen searching the internet and heard a few fathers talking about last year is that if you raise one wheel up so it doesn't touch the track it will make your car faster. By the same reasoning I say this is false and while I've witnessed fast cars that only have 3 wheels touching, I think it could make your car a little more shaky. So I'm going to stick with what I've learned from Newton.

After getting super smooth axles you should think about the back part of the wheel that will rub against the car, smooth this out and apply graphite here. Also put graphite on the part of the car that touches the wheel here. One more thing that I just thought of this year is the rubbing of the inside of the wheel on the raised part of the track that keeps the car in the lane. I'm going to make sure that part is smooth as well.

Wow, do I sound obsessed or what?
Hope this is helpful to someone out there.

Pinewood Derby 1 of 4

2009-01-15T06:16:00.000-08:00

The pinewood derby is a model car race for scouts age 8-10. It's a simple wooden car with plastic wheels held on with nails as axles. They roll down a sloped track accelerated only by the force of gravity. The key is to make the wheel movement on the axles as frictionless as possible by smoothing out all surfaces that the wheels may rub against.
This will be my third pinewood derby as a scout leader. The race is two weeks away and the last two years my son Shule has been in the program so we made cars together. The first year he made the "Mammal Mobile".
He decided to make it brown and green camouflage with yellow eyes in front. The pink sticker is just for identification purposes during the race and wasn't part of the design. It wasn't a bad car but we got to the race as it was starting and didn't have time to apply any graphite. This was a disastrous move and I'm pretty sure his was the slowest car that year. Each time it went down the track you could hear the squeaking of the un-lubricated wheels. His was the only car that sounded like that! I felt so awful but he won the "best paint job" award and went home not totally devastated.

With lesson learned about how important graphite on the wheels is the next year was much better. He made the "Titan" which was to resemble a ship. He placed 4th out of about 18 and it was really very close. This is his car on the right just coming in short of the second place winner in red. You can imagine how close he was to the third place car.

The derby is the biggest and potentially the funnest event of the whole Cub Scout year, it doesn't come without stress though. The biggest issue I have with the race is that building a suitable car is not a job that most 8-10 year olds can practically do. It is almost totally necessary to have help from family and scout leaders which is fine but because of the competitive aspect (trophies are awarded to top 3 places) it just gets a little weird knowing that the boys don't all get equal ammounts of adult help. In order to combat the potential injustice, our troop devotes 3 January meetings to working on the cars together so kids without access to tools and help at home can have a chance for adult leaders to help. Seems like a good idea but what we can do is still limited and we mostly just get the cars shaped and sanded which has a neglidgible effect on how fast the car is. Getting the wheels straight, spinning smoothly and the cars weighted up to 5 ounces is what makes most of the difference and these are the last things you do.

When I was a kid I remember participating in 2 derbys, I vaguely remember a red car and a blue car. I remember working on my back porch with the block of pine and a hand saw. I made a cut that looked fine from my angle but it turns out that it was croocked and the cut on the other end of the block went partway through where the axle was supposed to go. I was very upset and felt that I ruined my car. Tears were shed. Later I did get help to salvage it and we were able to make it so the wheel would stay on and I could race it, but I never had one of the fast cars. It was ok that I never placed, I would have liked to but looking back on it I'm glad I even knew how to use a saw by myself even if I couldn't cut straight. My boys aren't good with a saw, I think most 8 year olds who aren't raised on a farm or in a woodshop or something won't have the muscle to properly use a hand saw and heaven knows we won't let them get their hands on power tools. I don't even know how to use a power saw.

So I let my boys design the car, I cut it with the hand saw and they help with sanding and painting. I have them help a little as I spin the nails in a drill and smooth and polish them. I try to explain about reducing friction and why we do these things but until the race is actually happening, they pretty much only care about making their car look cool.

This will be Shule's 3rd and final race, but I now have Shazer in the program so we are doing 2 cars this year and we have brother against brother which adds a whole new level of competetion. So far we have the cars cut and have started to do some sanding. Shule's toad car is to the right and Shazer's rocket style car to the left (facing away from the camera to show off the fancy rear).I will do 3 more posts about the derby, one next week all about getting the wheels and axles ready for speed, I'll post some photos and share what tips I know. Then I'll do a short post just before the race to show how the cars turned out and another just after the race with the results of course.

50 State Quarters

2008-12-30T17:45:00.000-08:00

We started collecting the commemorative state quarters quite a while ago and just before Christmas I got the last one we were waiting for, Alaska. When Arizona's was introduced this past summer we took the family to the state capitol building where Janet Napolitano spoke and then representatives from the mint passed out shiny new AZ quarters to all the kids. Then they gave out free mint ice cream drumsticks for everybody. We then walked through the free museum that is a permanent fixture of the capitol building, it was a good activity.

So here is our collection (worth at least $12.50)

Clare and the Reasons

2008-12-18T15:24:00.000-08:00

Went to a show with Jon Stone over Thanksgiving and while I really enjoyed the headliner: My Brightest Diamond, for their inventive music I'm a real sucker for a poppy song so I also really liked Clare and the Reasons, the openers. Found this video posted on their myspace site and thought some of you would appreciate this classic 80's cover.

Pythagorean Theorem

2008-12-10T09:35:00.000-08:00

For ASU students today is reading day, a day between the last day of class and the first day of finals. At UofA I think they call it dead day, maybe because you're dead if you haven't studied for finals yet. It turns out that I'm going to school anyway for a test review session but before I get myself lost in cramming I wanted to write out the Pythagorean Theorem proof I promised. This one will be much more coherent than my last post.

I did it in two parts, part 2 is the only part that is necessary but I wrote out part 1 anyway in case you wanted to follow my whole train of thought as I was on the bus trying to prove to myself that 'c' squared really does equal 'a' squared plus 'b' squared.

You might also notice that the distance formula d = sqrt[(y_2-y_1)^2+(x_2-x_1)^2] is essentially the same thing as the Pythagorean Theorem. It comes up again and again, the 3D version is d = sqrt[(y_2-y_1)^2+(x_2-x_1)^2+(z_2-z_1)^2]

We sometimes speak of magnitutes of vectors and really it's the Pythagorean Theorem again.
Useful stuff.
Now I've got to get back to Laplace transformations, which are also very useful however I won't be giving you a proof any time soon! If you need help with math you should check out Paul's Online Math Notes, a very good resource for Algebra, Trig, Calculus and Differential Equations.

So Quadradical Dude!

2008-11-11T14:48:00.000-08:00

Lorin seems to think that I'm some kind of math whiz because I've been getting good grades in Calculus, while in reality it's a real struggle for me to understand all of the amazing math that other people have figured out. Through all the formulas and proofs I first try to understand why it works, sometimes I can and sometimes it's beyond me so in those cases I just try to understand how to use it properly so I can get the right answers!

One basic formula that I first learned before I cared about "why it works" is the quadratic formula. I just accepted it at the time and have used it since then. Now that I'm thinking more deeply about such things, I feel a little guilty every time I use it, like I'm copying someone else's homework. Well today I put a stop to the guilt, I decided to derive it without looking at a proof.

I know most of you probably don't care too much about this but Lorin was asking if my blog is about math, no it's not a math blog but I'll do this one post for him. So here it is Lorin, an old favorite and a standard of elementary Algebra: The Quadratic Formula. Use it to impress people at parties!

First factor out the coefficient of the x^2 term, you can immediately eliminate it by dividing both sides by it (for some reason I kept it around till the next step in my work). Then you must do the dreaded "complete the square" technique, I was feeling a little bold today so I did a few steps in my head on this one. Then it's just a matter of isolating x, get rid of the square by taking the square root of both sides (don't forget your plus/minus) and simplify. My circuits teacher recently used the quadratic equation in a different form as noted in the figure, the reason why he likes it is because of the repeated b/2a term. I had never seen it like that before but now I see where it comes from.

going back in time

2008-11-09T22:52:00.001-08:00

Jon Stone spearheaded a memorial for Only Anything in the form of a new blog with added mp3 downloads and photo albums. He set it up the framework and then opened it up to the group (band members and close friends) to add content at our liberty. The whole premise is that we just can't let go of the good old days so we are going to relive them by sharing our memories with each other (and whoever else will listen). It came together as planned and is still growing.

Shortly after its conception, a new spark was ignited as Jon Stone saw an upcoming Thanksgiving trip to Arizona as an opportunity to have not only a digital memorial but an actual flesh and blood Only Anything revival. It is not a total flashback as it won't be the original 5 together again with guitars in hand, we have some substitutes lined up. In fact, Jon and I will be the only original members participating but we are doing it in the spirit of old times. Any input from the other members is appreciated.

The events include playing a lot of music (old and new) and getting some recordings of it. In trying to decide what to play we have both picked some old songs and agreed to finish an old song idea and come up with a completely new one. The problem for me is that I have many new song ideas that are promising but all incomplete and time is ticking away. When I told Jon that I was planning on pitching 4 or 5 snippets of song ideas to him he got pretty excited and suggested that we instead raise the bar to do a whole new Only Anything album. Clearly this would be a long term project as we are both doused in schoolwork.

We quickly dismissed this idea as impractical and reverted our focus back to the few songs that we want to do this Thanksgiving. We really try to keep our feet on the ground but as an example of our stubbornness let's look at the new blog and call it what it really is: evidence of our inability to let things go. So, I wouldn't be surprised if in some time down the road there is an announcement of the new Only Anything album (limited release).

Don't hold me to that but feel free to browse www.onlyanything.com to experience music, photos, artwork and other artifacts from the greatest band that ever was. Some of those old songs are better than others, we just put it all out there though. Good or bad, it's history. Eventually we will get some better video up there, I know it exists.

little kid media rocks!

2008-10-10T23:59:00.001-07:00

Generally, I don't really like going to the movies. There's a lot out there that I'm not interested in. I find myself enjoying books and movies geared towards a younger audience. I tried reading Love in the time of Cholera because we got it from the library and some people have recommended it, but I hated it and after forcing myself to get half way, I realized I was wasting my time.
I now recommend to you 3 movies that aren't so "mature"; I have watched each one twice and I count none of that time as wasted. So here it goes, 3 movies that you should watch for a good time!

Son of Rambow - Totally liked it. Especially how Will says "Lee Carter". Watch it and you'll see.

Little Manhattan - A 10 year old in love, but it resonates with this 31 year old.

Millions - Good movie, Strange at parts but still refreshingly different. (the band Muse in soundtrack!)

We are complete

2008-09-27T17:25:00.000-07:00

It turns out that when I said in the last post "it may have been a dress rehearsal, a week before.." I was pretty much dead on. We were back at the hospital exactly a week later and Sophie came shortly after that!

shuffle

2008-09-27T17:13:00.000-07:00

I got a surprise package in the mail, an ipod shuffle. Apparently my friends love me a lot. Jon, John and Mat all went in on it. It is a must have for every cool college student. An ipod wasn't on my wishlist but, as I was setting it up I couldn't get over how something so small could play so many songs. It's my first mp3 player and I can say already that it's going to get a lot of use.
Thanks guys.

the limit of y as t approaches infinity

2008-09-10T21:14:00.000-07:00

This time she's not so early, but we still have some time. She just may be a little early yet; not as early as her previous babies but at least we got another ultrasound out of our false alarm trip to the hospital. Baby was probably not much more than 6 pounds as of Friday Sept 5. Contractions every five minutes for about 5 hours doesn't necessarily mean you're in labor. Who knew? It may have been a dress rehearsal a week before the actual debut. As we get closer to the due date, my classes have been getting harder. Physics is attempting to take over my world. The first exams are coming up next week.

school days for all

2008-08-28T16:22:00.000-07:00

School is in full swing and I think I should be able to keep up with it. I just keep thinking that at any moment now the baby may decide it's time to come, then we will experience what it's like for the kids to outnumber the adults 2:1 in this household. The kids may revolt and take over! I'm not really worried about that actually. Every afternoon we have the boys do homework at the table, sometimes there are struggles but it always gets done. I do most of my homework later in the night and some in-between classes at school. I've only gone to school for 4 days of course but I'm already making habits.

The boys on the first day of school

Sally fingerpainting
I now have my drums set up reasonably well with improved hi-hats. I don't play them with a baby inside though.

If you want more interesting blog stuff to read you can see the Only Anything Imaginary Band group blog that I have made some contributions to recently, it has been growing with lots of historical content from my teenage years. Oh nostalgia!

getting down to the rudiments

2008-08-20T02:03:00.000-07:00

On craigslist I met a Mr. Smith who lives in Maricopa and needed to sell his drums because his dog cries and complains every time he tries to play them. He doesn't like strangers coming into his house so he met me in the parking lot of a school and we did the transaction. I went to shake his hand upon greeting him and he pulled away putting his hands together in praying position and did a little bow while saying "please don't take offense". None was taken but Mr. Smith was turning out to be a real character. He sold me his drums for an extremely cheap price, that's the only way I'd be getting drums. I don't go on craigslist often but I'd been looking specifically for drums this summer and as soon as this ad was posted I jumped on it because I knew it wouldn't last 24 hours. The drums are of decent quality, Premier brand but the cymbals it came with are indistinguishable from scrap metal. Marisa had no problem with me bringing these into the house, we are hoping one of our kids will want to learn eventually and we can have a family band. For now, I'm the one who plays them and I'll get some tension out between school assignments by banging on them a bit.
Soon I will record them and add some drums to a song I'm working on. The song is called "Lonely Eyes" and it's turning out really well. Tonight I just recorded an electric guitar solo for the song and I think it's one of my best solos yet. The main part of the song is very moody and minimalistic, when the guitar comes in it's a very strong and dynamic moment.
I haven't recorded the vocals yet but a funny thing happened when I was recording just a rough vocal take to get make sure everything was fitting together. Marisa was watching TV at the time and some of the sound from it was getting picked up by the microphone, just as the last note is playing you can distinctly hear the phrase "nobody wants to die Bobby" loud and clear. I don't even know what show it was from but it sounds really cool and I think I'm going to leave it in the mix. Something for you all to look forward to!

bienvenidos bandits

2008-08-18T14:35:00.000-07:00

Jon Stone may be making some progress with me, if this ever sees the light of day, and I suppose it will, rss will see to that. There will be no twittering or tweeting and minimal texting; texting will be a last resort, will be sounding alarms, will be getting out the fine china. The world and its trends aside, this could be a great value if only for the sake of record keeping. So may this be the time it sticks, and with good fortune this blog will not be found among the company of my previous abandoned blogs. For this blog I have no expectations and it will have no theme except for my life, anything about my life is fair game. I will let it change as I change and I hope this will be its saving grace.
Soon Marisa and I will have child #4, I will start my second year at ASU and I will stop working as an all-night airport taxi van driver. All these things should happen in the next month. The boys are already back to school, 5th and 3rd grade. Next year Shule will be in middle school, an undeniable example of just how much life really does change.
That crazy job I've been doing this summer has had ups and downs, I can't imagine taking that job as a long term career but people do it. I work from 5pm to 5am four or five shifts a week. Too much wasted time. The good days aren't quite good enough to make up for the bad days. You may remember Chris Farley from SNL "living in a van down by the river!", well I've been spending my summer "living in a van down by the airport!". That's what it feels like. I'm nervous about getting lost in the technical studies again because that takes a lot of focus and a lot of time too but I'm thinking it's better than living in a van down by the airport for the rest of my life.
I did get to see the whole Phoenix metro area which was interesting; I know my way around pretty well now.
Modern Differential Equations, Circuits I, Computer Assembly Language, Physics II electricity and magnetism
That is my course schedule, it's only 4 classes but it's going to be a lot for me, the novice electrical engineer. There are some significant labs in there. I will probably be tutoring College Algebra again for about 5 hours a week. I want to tune pianos on Saturdays and I'm really getting the urge to play some music in a band setting again. The memory of Radiohead on stage at Grant Park has the opposite effect of discouraging these urges. Thanks to a gift from Kelby, the Line 6 Toneport, I have new home recording capabilities. I've started a few songs but it will be weeks before I finish because I only work on it one or two hours a week. I got a very good deal on a drumset and learning to play it is a long term goal, separate post on drums coming soon.