Getting Lost

I love this feeling.

After some sweaty late night tennis, hop on the car, start the engine, knowing where I am and where I want to go (home), but nothing in-between.

There’s a compass.

I am terrible at directions.

So I just drive in the general direction of where I think home is (I can do that thanks to the compass), and hope I’ll eventually end up on one of the few roads I know, and I can get home from there.

I’ve done it a few times and I think I’ve taken a different route every single time. Oftentimes I don’t even know what direction I am driving without looking at the compass. When I reach intersections… well there’s a 2/3 chance of getting it right (assuming the target is in one of the 2 quadrants in front).

From South Arm to my house at Blundell @ Gilbert, I think I’ve even gone to Granville and back once (those are roads in Richmond btw).

The stars are beautiful, and there are very few cars on the roads. The silence is relaxing. I don’t mind driving a little longer.

Try it some time! (I can help you get lost if you want. I’m GOOD at it)

Make It Fly

Just sent my oscilloscope PCB for manufacturing, and it will take about a month, so I’m thinking about my next project now :D.

I’ve always wanted to build something that flies. That’s my childhood dream.

I think it’s about time.

Did quite a bit of reading over the weekend, end up deciding on a quadrocopter.

There are basically 3 types of flying machines –
1) Lighter-than-air (LTA) vehicles – things that use hot air or helium (or *gasp* explosive hydrogen) to float in air, and motors just for maneuvering. Like an airship.
2) Fixed wing aircrafts – airplanes. Aerodynamically stable (if engines fail, you can still glide it back home).
3) Rotary wing aircrafts – helicopters, tri-copters, quadrocopters. Aerodynamically unstable, and requires precise electronic control to maintain stability (if engines fail, it will enter free fall immediately… bloody!).

Airplanes would be too hard on the mechanical side, since I know nothing about aerodynamics.

I was debating between airship and rotary wings… airships are just not cool enough =P and they are heavily influenced by wind, which may suck.

And quadrocopter is apparently the easiest to build/control among all rotary wing crafts, so I’ll start with that.

In my dream, it has a range of about 1km, sends a live video feed, and allow remote control, as well as GPS based auto-pilot (auto return home and waypoints).

Major challenges –


For the thing to be stable, the rotors have to make sure there is no tilt on all 3 axises of rotation (roll, pitch, yaw). And to do that, it must know its own orientation, which is a lot more difficult than it sounds, requiring an inertial measurement unit (IMU), usually consisting of a 3 axis gyroscope and a 3 axis accelerometer, along with a few other things (GPS, magnetometer) to correct long term drift. This alone will cost >$100. Also very complicated algorithms and crazy math.


High frequency = high bandwidth and low range. Vice versa.
To stream video, I’ll need at least a few hundred kbit/s, which means it will probably have to be 2.4GHz.
That will limit my range to about 1km with line of sight, but I’m hoping that won’t be a problem…
Lower frequency radio can do a few kilometers, but at tiny fraction of the bandwidth.


I looked at some motors used by other people. They draw about 10A (yes! 10 AMPS!) each, for a total of ~40A.
That means I will probably have to ditch my favourite NiMH, and go lithium polymer. Both for the energy:weight ratio and output current.


They (the government) don’t want whatever you build to crash into a 747. Which sounds reasonable.

Transport Canada doesn’t seem to have any regulations for “model aircrafts” except it must be <35kg. I have already emailed them for clarification. I want this thing to be classified as a "model aircraft" because it's the only class that doesn't require any license/certification to fly. In the US, they also have a restriction of a maximum altitude of 100m. That would be fine with me, too. I'm not going to launch my chopper into low earth orbit or something =P. For comparison, commercial airliners fly at about 10km - 100 times higher. They also have a line of sight requirement, meaning you must be able to see the aircraft with naked eye at all times. And if it's autonomous, you must be able to do manual override to get it out of trouble any time. I'll get to work =D.

Ghetto Air Conditioning

There are 2 ways to do everything – there is the right way, and then there is my way.

This is my way.


3 big chunks of ice with a little bit of water added to increase surface area.

I think the effect is more placebo than real lol. But still!

Experimenting with freezing point depression now. Theoretically, 10% NaCl by weight will give me a freezing point of -5C. We’ll see…

In an ideal world, I can reuse the salt too!

Deja Vu

Just picked up my lovely (shiny) saxophone today, after not even seeing it for the past 3 years.

The sound was nothing short of remarkable, depending on how you look at it – a perfect reproduction of constipation noise, interleaved with hyper-modern randomly-variable rate uncontrolled vibrato.


The victim. No photoshopping! It IS shiny :).

I think I deserted it right after I did my last RCM exam (there was a time when I thought paying someone to tell me how good I am is a terribly awesome idea).

Sharing the love!

Toy Story – Just Cute and Stuff


Warning: This post may contain spoilers for Toy Story 3. I’ll try my best not to tho. If you think you’ll ever want to watch it, proceed cautiously. If you haven’t and don’t think you will, think again =P.

hypocrite hypocrite hypocrite hypocrite hypocrite hypocrite hypocrite hypocrite hypocrite hypocrite

I’m the biggest hypocrite in the world.

After writing a whole blog post about how silly this 3D thing is, I just went to watch Toy Story 3, in 3D =P.

Some things are worth dying for.

Toy Story is worth living for.

I’m not sure if it’s the nostalgia or Rex (the dinosaur learning how to rawr), but I feel so kiddo again.

It’s one of those films that you don’t have to think about deeper meanings, or try to decipher some hidden message, or facts of life, or whatever.

It’s just toys. So little yet so much (no, this is not an attempt to sound profound). It’s all in the details. The character development is crazy for just chunks of plastic. And then their interactions and the lol moments take it to infinity and beyond.

The 3D is quite well done, too. There is no “dragons and demons ripping mortals apart”, but it makes the film so much more vivid. And it’s not grossly over-exaggerated like some other 3D films that just want to show off the technology.

Well worth the extra $4.

You’ll never be the same again! Well, not for a few hours at least.