4volt

Using Hobby RC parts in DIY projects

4volt — Sat, 05 Jun 2010 09:29:33 GMT

I’m always happy when I find a new kind of part that is cheap and easy to use with DIY electronics projects or robotics, the more standardized the better.

There’s a whole world of smart electronics and helper things in the hobby and remote control world that are great for robots and other things.

You probably already know that hobby servos are easy to control from any microcontroller like the arduino, but there are a bunch of other things that are just as easy to use. Generic motor controllers, battery systems are also equally as useful, but are sometimes hard to sort out the jargon and acronyms that R/C hobbyists use.

Some of the terms are pretty confusing, and a lot of acronyms and other R/C only rating systems are used. I’ve made this short reference to make it easer to sort out what all those things mean. I've found myself wondering more then once what the difference between an ESC and a BESC, or what a 2S2P 10C battery is.

Power / Voltage Regulation

ESC
(Electronic Speed Controller)

Uses a PWM signal to control the speed of a motor
ECS’s are made for either brushless or brushed motors (See motors)
ESC's are rated in Amps (A) for how large of a load/motor they can control

BEC
(Battery Eliminator Circuit)
Steps a higher voltage down to a lower voltage, a kind of voltage regulator
UBEC
(Ultimate BEC)
Same as a standard BEC, but made for higher voltages
BESC
(Battery eliminator speed controller)
An ESC with BEC
LVC
(Low Voltage Cutoff)
Keeps LIPO batteries from becoming too drained, which can be dangerous, usually a feature of a controller
DVM
(Digital VoltMeter)

Controller Acronyms

RX – receiver

Receives a control signal from the transmitter, output's a PWM signal for servos or speed controllers

TX – transmitter

(The remote you hold in your hand)

Battery Terms

LiPo, LI-PO, Li-Poly
Short for lithium ion polymer battery, the standard type of R/C battery
LiFe - LiFePO4
Lithium Iron Phosphate battery, generally safer then LIPO batteries, better shelf life, faster charging
NiMh
Cheaper, but generally not as good as LiPo or LiFe
S Rating (Like: 1S, 2S, 4S, 6S, etc)
Number of cells in a battery pack
A single LiPo cell is 3.7v
A single LiFe cell is 3.5v
A single NiMh cell is 1.2v
P Rating (Like: 2P, 4P, etc)
Number of parallel lines in the battery, each parallel doubles the mAh the battery can deliver

A 2S2P battery has 4 cells in 2 parallel lines
C Rating (Like: 1C, 10C, 20C, etc)
Amount of current battery can discharge in an hour
1C = Batteries entire capacity

A 10C, 500mAh battery can discharge at 5,000mA (5A) max, and have about a 6 minute life at max discharge

A 20C, 500mAh battery can discharge at 10,000mA (10A) max, and have about a 3 minute life at max discharge
Charging Bag, Charge Pack
A fireproof safety bag for storing batteries
LIPO Monitor
An alarm that goes off if the battery voltage drops too low. Batteries that drop too low can be damaged, or possibly explode.

Motor Terms

Brushless Motor
A motor that runs off of A/C power, and has no "brushes" that transfer current into the rotating spindle. Brushless motors are similar to stepper motors, but only have two coils.
Brushed, Canned, Standard Motor
A traditional DC driven motor
Coreless motor
A motor without the iron core in it's windings
Outrunner motor
Brushless motors where the casing spins and the center stays still

Motor is mounted by the back of the shaft
Low RPM's, high torque
Silent

Inrunner motor
Brushless motors where the center core spins, and the casing is fixed

Motor is mounted by motor casing
High RPM's, low torque
More efficient than outrunners

GB
Gear box, usually for planes
KVM, kv-RPM, KV
A motors' RPM in thousands per volt supplied

Servo Terms

KG Rating (Like: 10kg, 20kg, etc…)
Amount of force the servo can exert in kg/cm
Can also be rated in oz-in (Imperial)
G Rating (Like: 30g, 50g, etc…)
How heavy the servo is
Can also be rated in oz (Imperial)
Sec Rating (Like: 0.20sec, 0.50sec)
How fast the servo can rotate in seconds (usually for 60 degrees)
Digital Servo
Pretty much like a non-digital servo, but uses a microcontroller brain

Canon T2i/550D, Audio, and Auto Gain Control

4volt — Sat, 01 May 2010 00:02:46 GMT

A while back I posted a glowing review of the video performance of the T2i / 550D camera. I'm coming back now to review the audio quality and frankly there is not much to say.

The external microphone jack works well, and the T2i still uses AGC (Auto Gain Control) that automatically increases the gain (volume) on the microphone when things are quiet. That's fine for impromptu video where you don't necessary know what the noise levels will be, or aren't using an external microphone. The 7D also forces use of AGC but the 5D2 does not since 2.0.4 of the firmware.

For serious or even semi-serious film making, the audio is carefully controlled and microphones are placed to get the best audio quality, and AGC constantly trying to crank up the gain makes things sound very noisy.

What frustrates me most about this is such great manual control of the video on those cameras (now), it makes the audio control and quality seem very poor.

I would love to see Canon add a simple switch to turn of AGC for people that don't want to use it and I've actually started a petition that speaks directly to that.

http://www.petitiononline.com/CanonAGC/petition.html

If you agree, sign the petition, maybe just maybe Canon will listen and add a manual audio control just like they added a manual video control to the 5D Mark II and the 7D after it was released.

Canon T2i/550D Practical Video Review

4volt — Fri, 26 Feb 2010 10:58:56 GMT

I got my hands on the Canon T2i and I ran it though it’s paces, the things I was most interested in was the video modes and low-light performance.

To see the HD version downsized to 720p, you have to load the video from vimeo directly: Canon T2i, 550D Practical Video Tests.

T2i Vs. 7D

First a quick word about the T2i vs. the 7D. The T2i does not have that pro-feel that the higher level cameras have. The body is fairly light and it is most defiantly made of plastic, and you can tell when you hold it. For me that is not a big deal, it’s not worth nearly double the price to step up, though I do see the appeal.

Compared to “real” video cameras

In general I’ve been very impressed with the video shooting mode, in practice shots are easy to setup and the manual control works great. This camera lacks some features that a pro video camera may have, like a smooth auto focus, XLR audio inputs, and a power zoom.

Paired with a decent lens I feel that the video quality is just as good as the Canon XH-A1, a $3,000 HDV camera that I used in my last video shoot. In fact I would wager that the T2i is better in low-light, but I have no direct comparisons to show.

About the video codec

Video is captured in h264, at a high bit rate that is variable between 40 to 60 mb/s in 1080/30p and 1080/24p. I was unable to see any noticeable compression marks.

Needless to say, the video files are huge, order extra SD cards. A 4gb card is good for about 8 minutes of footage. Even though I knew that the files are big, I was surprised when the “No Space on Card” error came up, and it did twice while I was testing.

RAW still photos are about 20mb each.

I do wish that the camera settings like shutter speed, aperture and other EXIF properties were saved into the video, or at least the settings when video recording started. This is a minor issue barely worth mentioning.

Live View

A important feature for me is the ability to preview footage as it’s being shot, Live View mode in the EOS Utility works well, and a laptop would make a decent field monitor. The downside is that when recording the live view slows down to about 10-15fps, and motion is not a good representation of what is being recorded.

Another possibility is a HDMI field monitor, though I suspect a decent one would cost more then a average laptop.

When using live view and recording footage, the video file is written to the SD, not to your computers disk.

Capturing Video

Capturing video on the camera is easy and the manual controls are more familiar to me with my photography background then the manual controls on a pro-video camera.

Things that I wish it has was a live audio monitor and histogram, but those are minor things.

Auto-focusing is something that you will want to avoid when taking video, each time I tried this the lens over focused before it found it’s place. USM lenses are better, but I will probably still manually focus in most cases.

There is also a handy magnification button you can press for detail focusing that switches your live view on the lcd to 5x and 10x magnification.

Edit: You can start movie shooting with a remote, but you have to use the 2-sec delay setting on the remote, "immediate" mode on the remote takes a photo.

Another feature I missed is the power zoom for those very slow zooms, doing a slow zoom by hand is fairly difficult.

Audio

I have not yet had the chance to do detailed tests on audio quality, but my old Rode VideoMic works very well with it.

When the rest of my gear arrives, I may do another review of just audio qualities.

Editing Video

My computer is relatively good, a dual core 3.2 with 4gb of memory, a 4-disk raid 10 array and a GeForce 6200, and I've never had issues with editing 720p mpeg2 video. But my computer just doesn't have the power to keep up with the 50mbit 1080p stream. The video is fairly watchable in VLC, but in Premiere Pro 4.0 playback is very slow, perhaps about 3-5 fps. Editing this demo video was very tedious.

I’ll be looking to options for a new video card, and see what plugins are available that may be able to help.

Demo Video

See the video at: http://vimeo.com/9753969 (Or above)

I’m also publishing some of my test videos in a little collection. Most shots were done with the Canon 50mm f1.8 (non-usm) lens. The extreme close up shots were done with the same lens with a screw-on macro adapter.

Their is also one shot with the Sigma 70-300mm f4-5.6 lens.

It was important to me to do tests without any expensive specialty lenses. I believe both of these lenses are valued under the $100 USD mark.

All of these shots were setup in 5 minutes or less, on special rigs or setup was needed.

Room lighting is 4x65w flood bulbs, recessed.

No lights were used in the lit candle shots.

A 14w CFL desk lamp was used in the candle smoke shots.

Shutter speed was 1/30sec for all shots.

Conclusions

This is a great camera for a great price, it’s not perfect, but there’s also no un-resolvable issues.

Digital Video: The HD tipping point is now

4volt — Mon, 22 Feb 2010 22:29:17 GMT

Over the last few years HD video has been getting constantly cheaper, easier and better. I bought a used HD camera in 2001 (JVC HDGR1) for about $2,000 that was one of the first cameras under $10,000 that could do HD, and that it does at 720P, with some other deficiencies.

For a while now cheap HD has been available, for instance last year I bought a $150 camera that could also do 720P, but the sensor was small and noisy, that and the audio quality made the footage unusable.

However now the latest versions of digital SLR cameras as starting to be released with un-crippled features, things that independent film makers have been desperate for. Thinks like:

Full 1080P at 30fps and 24fps at a decent bitrate
Interchangeable lenses
Large sensors that allow for a shallow depth of field
Full manual control
Great low-light sensitivity
Audio input

Recently Canon announced the t2i, the first sub-$1000 camera that has all of those things. I think this is the magical price point that almost any serious hobbyist can afford.

How will this affect the digital video market, and the indie film market?

I think the effect will be very similar to the digital (still) camera explosion that has been continuing. More people will have access to high quality recording, but that does not necessarily mean they will be any good at it.

For the people that are skilled, or willing to learn the skills to take good video, there’s a whole new world of possibilities opening up.

I know I’ll be ordering one of the t2i’s as after it’s released, if you want to help, send in a donation. I would greatly appreciate it.

JP Image Book 2009

4volt — Mon, 22 Feb 2010 09:42:56 GMT

Every year I release a small “Image Book” of my favorite pictures, images and art. Some of the images I’ve published here, some are new to you.

To see last years edition see: Image Book 2008

As always I’m releasing the PDF for free, download and enjoy it.

I also have a printed version in limited quantity, and if you like my work and want to support what I do. I’m offering a printed version of this book as a thank-you for US donors, while I still have supplies.

Soon I'll be buying a new camera, my old camera is now about 5 years old, and has served me well over that time, but it is time for a new one. Any money you donate, I'll put right towards that camera.

So donate and and I’ll send you one! Be sure to mention it in your note, and include an address.

Otherwise here’s the files, download and enjoy:

Image Book 2009 (Print Quality, 56MB)

Image Book 2009 (Web Quality, 12MB)

Testing Jansen Walker Version 3

4volt — Mon, 15 Feb 2010 23:03:04 GMT

Over the last week I’ve been working on the next version of the Jansen Walker, this will be the 3rd release.

The goal is to make it much easier to assemble, faster, and 1/3rd larger using 3mm (1/8in) material.

The biggest change is that instead of using modified servos, which seem to scare a lot of people off, use geared motors which are about the same price. That will make the electronics side easier, perhaps slightly more expensive depending on your controls.

The new version will use the Tamiya Twin-Motor Gearbox, that has a good 203:1 ratio that is ideal for a medium to low RPM walker. It’s $10.95 at SparkFun.

I see three obvious ways to control the walker electronically:

Very simple: switches and batteries
Direct wired buttons to the motor and battery would work well, but have no speed control
A generic R/C setup with a remote, receiver, and two small speed controllers. I think this would be fun.
An arduino or any microcontroller with a motor shield

I’m also playing around with ideas to make assembly easier and faster. Currently it takes about 4-6 hours to assemble, mainly because of all the legs and joints. There are 5 joints per leg, and there are 12 legs.

The next thing I'll be trying is nylon tubing and compression using bolts, that should allow for secure joints that still still rotate freely. As soon as my parts arrive I’ll be testing this method, I think it will shorten assembly time by as much as half.

Laser Toy Blocks

4volt — Sat, 06 Feb 2010 09:26:09 GMT

For Christmas this year I made some custom toy blocks with friends and family initials.

The blocks were cut from square wood stock into 1.25in cubes. The stock I used was indented for banisters, and had peg ends, but they were easily cut off.

I made a batch of both Oak and Fir. Oak turned out fine, and is what is pictured here. The Fir blocks came out with a more slightly more desirable finish since the end grain was more smooth after sanding.

Setup

First I taped down a 3mm (1/8th in) board and cut the appropriate number of squares at the same size as the blocks.

Cutting a grid instead of a single square helped to keep each block in the right spot for engraving.

The last task was to choose the fonts that would appear on each side of the block then lay out 6 versions of the same letters but different fonts to engrave on each side.

I chose some initial fonts from dafont.com, choosing the fonts was half of the fun.

Packing

I made a custom version of my original papercraft folded box, check the included zip file for a box that fits 3 1.25in blocks perfectly (33x99mm).

Power required to emulate a human brain

4volt — Sat, 06 Feb 2010 07:27:47 GMT

Recently, I posted a article about how much computational power it would take to emulate the human brain, and my calculations were off by a factor of 10. I've corrected my estimates and here are the updated sections:

Emulating the Human Brain

The Blue Brain Project has successfully simulated 1 cordical column on the Magerit super computer (100 TeraFLOPS), and human brain has an estimated 1,000,000 columns.

So with 5.2 ExaFlops, one could emulate 52,000 cordial columns. And that’s 1/20th of enough power to emulate a human brain.

To emulate the entire human brain you would need approximately 100 ExaFLOPs

That's a lot of FLOPS!

I chose the above estimation because many others rely on calculating how many operations per second the brain can processes, not how many computer calculations to emulate the brain. I.E. It takes many more computer computations to emulate a brain computation.

Fore some more notes see: http://www.smartcomputing.com/articles/2002/s1302/39s02/39s02.pdf

Conclusion

Henry Markham in his recent TED talk, thinks that a human brain could be emulated in 10 years.

I agree with his estimate, using Moore's law 10 years seems like an achievable goal.

If you are interested in the subject you may also like Ray Kurzweil's research and books.

Stel Music Video

4volt — Wed, 03 Feb 2010 21:13:48 GMT

'Stel' is a song I've been meaning to make a music video for since I released it in 2008, and with a few effects I wanted to experiment with and the short length of Stel made it an ideal test.

I used 2 effects pretty heavily, Adobe Premiere's "Time Warp" effect and PSCombine in video mode.

I used Time Warp to "morph" between stills, and all the video you see here, is actually still images taken with my still camera imported as video. Once the stills are imported as video I used Time Warp to slow them down by 200-500%. The result is an interesting morphing effect with the somewhat disjointed photos, and a buttery smooth motion between photos that are similar enough.

To add some randomness in the titles and some short flashes, I used PSCombine, it works well in short bursts.

For an HD version, go to: http://vimeo.com/9187331

Download the mp3 at: http://4volt.com/music/albums/array/

Total Processing Power of the Internet

4volt — Mon, 18 Jan 2010 23:38:03 GMT

As a brain exercise I decided to try and estimate the total processing power of all the computers on the entire internet, and see if that is enough processing power to emulate the human brain.

Since this is an estimate, I will try my best to figure it out with public data.

Here was my process:

Total Number of Computers

No one knows exactly how many people (computers) are connected to the internet since a single IP address can be shared with any number of pc’s, but the best estimate I was able to find was here: Internet World Stats

They use population statistics and penetration data to estimate this. This does not include extraneous connected devices like gaming consoles, or other devices.

Total Computers: 1,733,993,741 (1.7 Billion)

Effective Processing Power per Node

Since all the computers are separated by the internet, I chose to use SETI@home as a benchmark for the effective benchmark of how much processing on average a node can handle

According to BOINC stats, Seti has 186,250 active computers (more inactive ones), and the peak processing speed is 704.507 TeraFLOPS (tF). (As of 01/17/2010)

That’s 3.782 GigaFLOPS (gF) per node.

Also, on average computers running SETI are probably faster then the average computer online, especially considering poorer countries. So lets round down the average to 3gF.

3 GigaFLOPS is much lower then the peak processing power of a modern computer, a (Intel Core i7 965 XE), can process about 70, while some of the newest GPU cards can process upwards of 1,000 GigaFLOPS.

This leaves me to believe that tele-processing is very inefficient compared to traditional supercomputers, though it is not without advantage.

Total Processing Power

Now, assume all 1.7B computers were all running this hypothetical peer to peer processing application, and bandwidth was not a bottle neck.

1,733,993,741 * 3 = (5,201,981.223 TeraFLOPS, or 5.2 ExaFLOPS)

In case your wondering:

1 Peta = 1,000 Tera

1 Exa = 1,000 Peta

Currently the fastest supercomputer is “Jaguar” with 2,331 TeraFLOPS. (Top 500 November 2009)

Emulating the Human Brain

The Blue Brain Project has successfully simulated 1 cordical column on the Magerit super computer (100 TeraFLOPS), and human brain has an estimated 1,000,000 columns.

So with 5.2 ExaFlops, one could emulate 52,000 cordial columns. And that’s 1/20th of enough to emulate a human brain.

To emulate the entire human brain you would need approximately 100 ExaFLOPs

That's a lot of FLOPS!

Fore some more notes see: http://www.smartcomputing.com/articles/2002/s1302/39s02/39s02.pdf

Wrap-up

After reading more about the Blue Brain Project, they are emulating a cordial column, as well as analyzing and visualizing that data, which is not necessary for a independent AI.That coupled with the inefficiencies in communication with tele-processing, I suspect that there is a lot of improvement that can be made.

Henry Markham in his recent TED talk, thinks that a human brain could be emulated in 10 years.

I agree with his estimate, using moore's law 10 years seems like an achievable goal.

If you are interested in the subject you may also like Ray Kurzweil's research and books.

Alternatives

More likely a successful AI would be a efficient Emergent-type hive AI. Where independent nodes contribute to a beneficial goal with independent actions. This would not look like a traditional AI to us, the patterns would probably to numerous and vague to track accurately.

This was meant as a thought experiment, if you have any comments please leave them. I will revise this article as I see fit.