SPEAKER update

Here is the LM386 referred to in the last post, hastily hacked together

I think I will remount it, perhaps on the top? back?

And here is a sneak preview of the PORTRAIT OF A KROGAN my roommate painted in its incomplete form. Once I mount this badass speaker/portrait, and once my other roommate, the photographer, takes some good shots of it, I'll post the finished version.

I wish I had 4 more for a "hidden" 5.1 setup.

Mass Effect is so much fun. I simply must resist buying Mass Effect 2 until Spring Break, I MUST!

SPEAKERS!

WOW it's been quite a while. I suppose that's okay, last semester was pretty busy. No one reads this anyway.

Well, I recently picked up a Gakken "Learning for Adults" (or was it "Science for Adults"? I don't remember, it was in Japanese) magazine with a kit to build a 7 cm fullrange SPEAKER! I'm not talking about build a speaker box and throw in a driver, I actually assembled the driver! It was mostly gluing but there was some careful positioning involved too.

I had been wanting to get some fullrange drivers and try my hand at making some interesting speaker cabinets that help get the best sound from single drivers.

I was too excited to take pics during the build stage, so here are some pics of the finished product (courtesy of David). I built a total of three speaker enclosures out of CARDBOARD. It's uncanny how you can modify sound from enclosure design. (Box 1 omitted because it really was just cutting a hole in a box and throwing the driver in, these were built piece by piece).

Box 2
I've decided I don't like gum tape on speakers (not messy like this anyway).




Box 3 (Design taken from the magazine)

Look at that maze of a speaker! Really helped the bass.



Beautiful.


I also threw together an amp with an LM386 low-power speaker opamp I had laying around as well as other parts I also just had laying around. It's still in breadboard form if you can't tell from the pics. Sounds pretty good for cardboard and batteries!

On the note of sound quality; I thought I had been exposed to 90% of what Hi-Fi had to offer. I've listened to most of the top headphones from the top companies, and I've demoed a vinyl/tube amp/loudspeaker setup complete with actively-shielded cables at a Hi-Fi store that one could sell to buy a pretty nice car, we're talking baby supercar. The room was even set up with diffusers and bass traps, the works. Yet there's something about this single driver, especially in the MIDS on vocals, that is just brand new to my ears, like nothing I've heard before. I don't believe I've ever heard vocals so true.

Frequency response was a bit off, however. There seems to be a region in the spectrum missing from the speakers, somewhere in the low mids or high bass. This is probably a consequence of speaker design, material (CARDBOARD, I need to start working with MDF), the driver (<3", most fullrange cabinets I see are for 4" fullranges), etc.

I think I've stumbled upon the subject for my Spring project...

Oh and maybe an amp too, since there always has to be something electronic.

FORMULA SAE

So it's official, I've joined Cal's Formula SAE team! I only have a few days experience working with them, but so far I love it. The people are great and I cannot WAIT to see this year's car up and running (which won't happen until next year, probably). The pic is of me in the car from the last competition, blurry because my cameraman didn't take into account my cameraphone's delay when snapping it.

The new engine is supposed to be dyno tested this weekend, I wonder if I'll get to see it, or more importantly hear it.

Why haven't I done this sooner? I haven't really done much with any club at Cal but I can see myself spending 80% of my weekends helping out with this. I loved metal shop in high school (I took metal 2 twice, never learned TIG though, which is hurting me right now), I love modifying/driving my RC car crazily, and I drove my Corolla wagon a little too ridiculously in high school. The only bad thing is I really can't pull myself to do work after coming home from the shop on the weekends since I'm so tired (or maybe that's just an excuse).


If you haven't heard about the UCwide "walkout", well, here is a pic I took from what happened at UC Berkeley. It was so massive I could barely hear what was going on, but the chanting/shouting was kinda fun.

If I get time/energy this weekend, maybe I'll post pics of my laptop speaker repair (it hasn't happened yet by the way, and yes I teased at it during the last post). I took apart my laptop and took them out, and to my surprise, it still works great! However, I ended up with an extra screw, which was very unsettling. I spent an hour partially taking it apart and putting it back together to try to figure out where it went, in the end I guess it's nonessential. I'll have another chance to figure it out soon though, during the repair.

2nd Cardboard Shelf!

This has been done for a while, and I have been a bad blogger, I've neglected to update. I updated, but I updated on facebook. To be honest I don't think anyone visits this blog anymore; especially after nearly 2 months with no updates, the latest being about how I'm running every other day now (still am though!).

Here is the album on facebook. The link should work for everyone regardless of facebook membership status-at least that's what it tells me. Oh-I just found out this nulls any notion of anonymity on my part, but that's okay.

The gum tape REALLY brought out the front, it just looks GREAT, compared to the last shelf. The last shelf was "sealed" with strips of brown paper bag lined with wood glue.

I might be repairing my laptop speakers this weekend if any readers are interested in seeing an MSI Megabook S262 teardown; but it's just a simple cable replacement, nothing too noteworthy.

That's it for now.

C25K!!!!!!!!!

It's official, I've begun the Couch-to-5k running program! A friend of mine linked it to me, and the intro made perfect sense:

"Too many people have been turned off of running simply by trying to start off too fast. Their bodies rebel, and they wind up miserable, wondering why anyone would possibly want to do this to themselves."

The last time I tried taking up running was by treadmill at the school Recreational Sports Facility, Fall 2008. I really did wind up miserable, the only thing keeping me going was my persistence and the satisfaction of a mirror (and a girl, surprise surprise). I was doing okay, at 6 days/week (I lasted a couple of months as well! And this was with weightlifting too), but I was pushing myself to the extremes, exhausting myself and torturing the hell out of my lungs. I always dreaded it.

Now running is fun! The program calls for 3 runs/week, I've done 5 so far this week! Granted, I've only just finished the second week, but I think I'm making good progress as each transition feels smooth and easy.

Running outside around town, parks, and residential areas is so much fun! There's still a lot of places in this city I haven't seen :D

I bought this the first day:

Purchased at Tuesday Morning (yes I'm cheap), on a Tuesday Morning lol. I realized I didn't have any kind of digital watch, and the program requires a way to measure either running distance or time. Also, as you can see, the wristband is interchangeable. It was either this or a USC digital watch, which would have misrepresented me greatly lol.

The wristband reminds me of Keith Urban, who I had just seen the weekend before the Tuesday in concert with Sugarland. Coincidence? lol. I wonder why he always wears it, maybe his extreme shredding (yes he can shred, I bet he could do metal if he wanted to) causes his forearm and hand to sweat a lot.

Also, I bought some blue Sheaffer ink and a Sheaffer calligraphy fountain pen (which was ridiculously cheap at $6, no converter though D:).

Looking through my notebooks, I think I'm improving greatly (although I don't really write down anything meaningful, I practice by writing whatever I'm listening to at the moment). Credit for top stanza goes to Brad Paisley, the bottom line from Queen. The paper is a Clairefontaine notebook.

The ink is quite... thin. It's a perfect match for the gold-ish fountain I got for my birthday in this post, since it seems to have a bit of a problem in the flow department with my other inks (it was nearly impossible to get a good line with the included ink cartridge!). The flow is nice and even now, and more importantly: reliable. The calligraphy in that post is just hideous now that I look at it.

This calligraphy thing is so addicting! I need to learn a new font.

Waterproof and Water Damage

Well, I haven't RC'd for more than a week, but I will post some things that happened the last time.

Upon my latest run of the KNEX NEW BRIGHT HYBRID, I encountered a motor problem. It just died. This was unusual because it was the stock Losi Mini-T motor, I hadn't opened it up or modified it at all. I was expecting reliability! It turns out either the plastic washer, or armature lamination cover had melted and covered the commutator! I wonder if this ever happened to any Mini-T's.
The melted washer.
The armature. Note the melting at the edges of the white plastic rotor-caps at the upper left and right, and the entirely missing cap at the bottom. The comm has been partially cleaned in this picture.
The comm. This is after I began to peel away the plastic.

I can't help but wonder if this was catalyzed by the one incident from a previous run, in which my roommate was driving. He attempted to climb a steep grade, where he was mostly successful but got stuck and kept holding the throttle. If you continue to apply a current to a locked DC motor, it essentially becomes a short circuit. The current going through the coils is no longer AC (it is usually AC from the comm constantly repositioning itself with the brushes, go read something better explaining how DC motors work if you don't understand), and therefore the AC impedance of a coil is gone and the resistance basically drops to 0. This is almost as if the battery was short circuited.

After the incident, I did smell melted plastic, but I had inspected the gearbox and there was no signs of melting. I hadn't realized it then, but it was obviously something inside the motor.

However, on the run that the motor failure occurred, the truck was running on relatively flat ground (leaves, twigs, etc) and the failure was quite a surprise.

Waterproofing

In order to run the truck through the local creek, I had previously put the receiver and speed control into little baggies, and then zip-tied them shut. This worked okay, but then after one run I discovered water inside one of the baggies (the receiver one!). The servo held up well with no waterproofing whatsoever.

This time, however, I wanted to run the truck on the beach, and maybe try to tease the water a bit (it ended up almost floating out to sea!), so I needed something a little better.

Here was the idea:

And the execution:




The servo I opened up, and applied liberal amounts of grease to the seams. I neglected to take photos.

The moist beachy-area I had intended to run on was just water when I went, alas, it was high tide. I continued on to a rocky area, and it was either dry driving, or floating out to sea. Needless to say, it worked pretty well! I hadn't brought my camera, so sadly there's no good photos/footage of this event.

I think it would have made a decent raft if I could have sealed the air inside the tires somehow.

While the run was a success, I cannot say the same about the aftermath. Laziness has set in (I'm in class now though) and I neglected it for nearly a week before performing maintenance. This was made even worse because the water was not fresh, creek water, it was salt water which corrodes much faster.

I don't know if this happened during or after the run (probably mostly during), but some real general chem stuff happened.



This is the battery plug (and the receiving end on the speed control, and a part of the wire where stripping occurred). Note the blue deposit over only the positive contacts. I believe this is cuprous (cupric?) chloride: the contacts are probably made of copper, perhaps nickel-plated, and they were exposed to an aqueous solution of sodium chloride (the bay). The positively-charged electrode of the battery attracted the negatively-charged chloride anions, and formed the precipitate. I don't know if I'm right though, it's been years since I've taken general chemistry and I forget most things a month after classes anyway.

Also, the motor, which turned freely after the run, is now locked tight. I'm guessing some internal rusting caused it, but I don't really want to find out. The truck has been shelved since.

It's been fun, and completely worth it. I just wish somewhere in this city there was some MUD I could plow through.

Photo quality is back

... After just one more pic, I swear! I mean, this pic wouldn't be possible with anything other than my cell cam. It'll be obvious, don't worry.

Before, this blog has had a maximum of 2 confirmed (by comments) readers at any given time, with previous picture quality. There hasn't been a comment since the poor picture quality began. Anyone remember this failed attempt at fixing my good ol' Konica Minolta X50? Tried to charge using the external DC jack, but then realized it doesn't charge from that jack, then tried to power from that jack ~5 volts from USB. Then I found out the USB supply current was too low for the camera to actually operate on.

Now, I had this idea a few months ago, but then forgot about it until now. It's so simple.

Yep. Just 4 AA's, NiMH, rated at a total of 4.8 volts, while the dc jack on the camera is asking for 4.7 volts. Close enough, even alkalines worked, which provided nearly 6 volts. I measured current draw, and it was only a little over the USB 100 mA at 340 mA. Okay, it's more than three times as much, but its still very low.
I'll probably re-do it with a longer cable, as this will get cumbersome when I try to use a tripod, but it worked. Also, yes that is the 4-AA holder that I also used as a receiver pack on the last post.

10 Cells

On Saturday, after the old Ni-Cads had been cycled a few times with my discharger, I headed out to a nice little spot (in fact the only spot with flat dirt here in Berkeley) west of here to finally see what 10 cells could do-at least with my 20 turn Stinger/Flash hybrid.

It just so happened there were a bunch of guys running nitro RCs! As I was setting up for some fun and getting ready to challenge their Losi XXX-NT (I think) to a drag race, since I was feeling confident with the 10-cell setup, I pulled the trigger (throttle) ever so slightly, it moved a little and--death. It died right there. The ESC had died. It had run on 10 cells before.

I inspected it later that night, nothing seemed wrong, and it was rated for up to 10 cells. I went back on Sunday with the very old and weak (but dependable) Elektra, rated at 6 cells and only handling down to 20-turn motors.

It was still fun, but I felt it could have been a lot more fun. I still went and got it a bit dirty though :D Enjoy

That little red thing in the back is a ghetto (but effective) air intake to cool the motor.









Where the intake leads to


And another shot









My favorite shot








The Elektra, the purple heatsinks match the rear purple shocks lol.

The failed ESC - Duratrax Streak.
I don't know if you can blame it, I was pretty bad at soldering when I replaced the 14 gauge with 12 gauge. But it was working fine this entire time. Also, why on EARTH would you release an ESC rated up to 10 cells and down to 12 turns with 14 gauge wire, a tamiya plug and bullet connectors? Where are the solder posts? It was very cheap though, so I'm not too sad.

I kind of messed up that motor mount that I described a few posts ago, so it'll be a while before I get the time and money to work on it again, but I figured by then I might as well go brushless :D

Also, for when I get back into this, I picked up a disposable camera that can be used as a battery zapper, for the next time I decide to bring out the old NiCads. I think I'll document it and everything, recording down charge cycle statistics before and after the treatment, and I'll try on the entire pack, and per cell as well. Hopefully there will be graphs.

Funny story about how I got this also. So, all i really went to Walgreens for was a bag of chips, I had a 6" sub for lunch and was feeling a bit hungry again, and then I passed by the disposable cameras and remembered the whole zapping thing, although I had intended to focus more on school and not RC again for a while. Anyway, I ask the clerk if I can have one of their old disposables, she asks the manager, and I'm denied. Then, as a stroke of luck, some girl happened to be there, ready to develop, and offered me hers. This was all in front of the clerks and manager too. Okay, I'm sorry, that wasn't funny at all.