Thursday, October 1, 2009


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.

Friday, September 25, 2009

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.

Saturday, August 1, 2009


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.

Friday, July 10, 2009

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.


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.

Monday, June 29, 2009

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.

Friday, June 26, 2009


Well, the Knex truck has been put on hold for now. I got tired of not being able to go very... off-road.

The motor I rewound was FAST. When it worked. My crappy solder-joints kept coming off and ruining everything. So I bought a stock Losi Mini-T motor ($15, GASP!) and all is good.

I've been meaning to get the Rustler back in operational condition, and so I said, what the heck, I'll go straight for the 10-cell setup I've been wanting to try for so long. 6-cell is standard.

There are a total of 14 cells in this pic! Because 12 volts is too much for the receiver to receive power from the ESC, I needed a separate battery-pack to power it. Luckily I had a 4-AA holder left over from my electrical engineering course.
For the main battery pack, basically I just wired a cheap 6-cell 1500 stick pack with a 4-cell 1500 stick pack. The 4-cell is a chopped-up 6-cell, and that was the only soldering I had to do for the entire thing :D

I use Duratrax/Andersen Powerpole connectors, which have a low resistance compared to the typical "tamiya" connector, but they're very unpopular nowadays compared to deans and traxxas connectors. However, you can't do this with deans or traxxas:

I just turned two battery packs into one! And its reversible! This is made possible because the Powerpole plug is modular, and more importantly, has no gender (or is it hermaphroditic? who cares). I don't know about the current carrying characteristics (o.o alliteration) when comparing the three types of plugs, because the Traxxas one is relatively new and I've seen the contact plates, they're pretty big, but for my brushed-motor, NiCd application the 'poles are super. I'm glad I switched so many years ago.

How did it run? Extremely poorly D: My comm has breathed its last breath, as I had overworn it, and the NiCd's haven't been run in years, so it's understandable they were slower than my 6-cell-matched NiMH packs.
The badly worn comm. It's hard to see but much of the copper is missing.

For the battery packs, I read around about zapping them with a high voltage to revive them and loosen the internal crystals killing their performance, but a tip from a guy at my local electronics shop made me reconsider. He told me to beat the packs. It made sense! However, now, after a few charge/discharge cycles it doesn't seem to help that much. I haven't tried it in the truck yet, and because of the comm's condition, it looks like it will be quite a while before I get to see 10-cells and 13-turns come alive.

Speaking of batteries, I finally made a discharger so I could perform battery maintenance better. The local electronics shop had the standard automotive 1157 bulbs for $1 for two. I bought out their 6, and made a 6-bulb, 12-amp discharger. The closest automotive parts store wanted $2 each, so I didn't opt for the full, standard 10-bulb discharger. So the total cost was pretty much the $3.50 for the 6 bulbs, since I had some old 12-gauge laying around, and I have a bunch of the powerpole plugs.
The finished discharger.
The discharger in action (it got a LOT brighter with my 6-cell sidexside NiMHs, saying a lot about the performance of shotgun-style construction, which is shown in the picture).

The bulbs get blindingly-bright (with the NiMHs) and really hot. Each one draws 2 amps at 7 volts! This seems terribly inefficient, I've seen LEDs on lots of the newer cars (for everything but headlights) but why don't they put them on all cars now? I wonder if the prius and other hybrids use more efficient lamps.

Hmmm... What else was there? Oh yeah. I spotted a 9.6 volt battery charger and battery on clearance at Radioshack the other day for $4. Those batteries for crappy RC cars are pretty much 8 AA batteries, like my transmitter, and I already had 8 NiMH AAs for my transmitter, and a plug that would work with my 18R transmitter (it doesn't matter I can still take out the AAs and use them with my traxxas TQ), so now I have an easy solution for charging my transmitter batteries (previously I would have to charge 4 at a time).

As for the Rustler, I've had the 20-turn armature from my Stinger motor for quite a while now just sitting in my toolbox, with its comm in relatively good condition. I went out to my local park with my NiMH packs, and while it was impressive for what it was (A "frankenstinger", a stinger armature from the old traxxas electric vehicle standard in my Reedy Flash BB can with stiff brush springs and quad magnets) the enjoyment I had from the raw power of the 13-turn was gone. It sounded underpowered. It did go pretty fast though, and I managed to completely screw over my ESC D:

The Stinger. Apparently they gave it a makeover in recent years

Since traxxas electrics were (and are) extremely popular RC vehicles, I wonder if this could be like the standard "small block" that everyone has and is familiar with. Nah, that's probably where competition stock motors would lie.

So I think I'm going to put away the RC for a while. I really miss my old small town, living in the city, I couldn't RC just anywhere. I've gone far and wide just searching for places to have this kind of fun. Looks like I'll have to start getting into microcontrollers finally...

Friday, June 19, 2009


While browsing Goodwill last week, I came upon a ridiculously cheap "New Bright" Hummer H3 rc truck, the kind you find in Wal-Mart. There was no controller, so it was marked at $2, $6 if it had the controller. It had a 9.6V battery inside, and seemed to be in order. I figured maybe I could have some fun with it, use the body for future vehicles, since I've been looking into a crawler, what with their immense rise in popularity in recent years, and my thirst for the scale looks (of some) and the solid axles. My Rustler and 18R both have independent suspension, which is good, but I wanted something new.

Upon closer inspection, there were some cool things I noticed. My experiences with cheap RC cars as a kid led me to think that they used irreversible assembly techniques, so I couldn't tamper with anything as I usually loved doing. This little truck was held together with mostly philips screws, and some parts that snapped together. The entire battery/electronics compartment had a nifty locking mechanism and came clear out (after unplugging the steering motor and drive motor) with two screws.

However, the overall impression was still typical. There was no front suspension, at all. The front steering knuckles were mounted on stationary arms. Interestingly enough, they had shocks! same as the rear, except they just didn't do anything but look pretty.

The rear end had about a micron of suspension travel (laugh here). See if you can tell which picture is compressed and which is relaxed!

There was about an Angstrom of available articulation.

I thought about some chassis/suspension modification. Installing my own electronics would be very easy. However, any modifications would be difficult and I would have to custom-fabricate parts with materials that would have been costly.

It occurred to me then, what I could do. I had all I needed for a hybrid RC K'nex/New Bright monster truck!!!!! I had been wanting to do this for a year (here's the post to prove it! That was a working rolling chassis), but with all genuine K'nex parts (wheels, gears, etc etc). However, as I had been tossing around the thought for a year, every part of it just seemed very hard to do properly, and wouldn't perform well or be strong at all. The gearbox would have very many gears for a good reduction ratio, or I would have to use the weak supplied K'nex 130-motor-driven gearbox. The suspension system would be very weak and prone to breakage, as well as the steering system. The large K'nex tires are very narrow, and would have to be stacked, but I didn't even have any. The only working universal joint design I could find was HUGE and couldn't be trusted without tape.

On the other hand, the New Bright rear axle was a complete solid-axle drive unit, with its own motor inside. I could easily detach it and use it separately without any complicated mechanical connection.

I quickly set to work on a prototype.

The front axle is missing because at this point all I had was a chassis and a rear axle, which was a given.

Even though the axle link system I used involved only two links, which were hard-fastened to the axle, the knex rods were flexible enough to allow some articulation. The rods conveniently stuck into holes right under the shocks (which were very stiff, there would have been still more articulation had the springs been softer. However, the goal of this project was to be as cheap as possible).
There was more overall suspension travel:

When it came to the front end, I tried making an "axle" out of knex. It turns out that the difference in size of the knuckle pins and knex rods were too great, there was a lot of slop and the toe-in varied by as much as ~40°. So, I ended up cutting the "axle" from the chassis itself.

A knex rod zip-tied to it aided mounting. This project has taught me the value of zip-ties.
At this point, I had a rolling chassis+transmission.

Silly truck, that isn't your body!
That round part in the front turned out to be the only thing preventing optimum servo mounting, so away it went. I used the stock steering link to link the two knuckles together, but can you guess what I used to link the servo to the knuckles?

Custom blue plastic tubing?

That's right, it's a ball-point pen. Fit the bill perfectly, and was free since I had one laying around. (I just remembered, the cap from this pen went towards a headphone recable I did in 2007).
I installed all the electronics, and it was, well, slow.
Here are some more shots.

I've since made it waterproof (all I had to do was bag the receiver and esc), installed the motor from my car (which was way too fast, kept spinning inside the pinion gear), and rewound the original motor. It was loads of fun with the 18R motor, but I wanted to drive my 18R again (also the 18R motor melted the plastic gearbox housing a little bit and it upset the gear mesh :/)

I've been drifting the 18R, all I had to do was tape the tires. It's loads of fun and makes me want to keep it again. I'll post a crappy vid soon.

As for the rewound motor, it went from 30 gauge (or maybe even thinner) and NINETY-FIVE turns to this cool green-enamel-coated 26 gauge I got from radioshack and twenty-nine turns. I think it's safe to say I have a nice hand-wound modified motor lol. Maybe not nice since it's now my number-one source of problems, but it's a good in-between the performance of its stock form and the 18R motor.

As for "crawling" ability, it sucks. It's not 4wd and the gear on the axle is so big! It gets in the way very often. Also the tires aren't the best for the task (hard compound with chevron+spikes). I wonder if I cut off the spikes will it be better? Boil the tires? hmmmm

Still it's fun to try.

All that water isn't good for the axle, but some WD-40 fixed the problem and prevented new ones

Shot of the motor armature before and after winding. Sorry for crappy image quality, still using the phone.
That green wire looks so cool, the picture doesn't do it justice.

FINALLY, that's it for now. Actually there's more to post but I feel I need to start a new one. Tomorrow.