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Posted by Jack Crossfire | Jul 19, 2015 @ 12:22 AM | 3,067 Views


Modified the RC truck cam to make it slightly higher & record uncompressed frames without the wide angle attachment.



Truck cam from February, with wide angle lens & JPEG compression.


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Posted by Jack Crossfire | Jul 18, 2015 @ 01:35 AM | 2,683 Views








The answer is yes. Developing for iOS is expensive. A pile of I gadgets came from the day job, with plans to support the iWatch. It gets more expensive as the gadget gets smaller, with the iWatch the most expensive, since it requires the phone, which requires the mac.


The 13" macbook from 2012 lasted longer than any other laptop, with no issues in 12 months of daily usage. To be sure, duct taping the keyboard to stop it from glaring sunlight gummed up the touch pad & the screen. Once the gum wore off, it was useable again.


The typical product nowadays is a gadget that communicates with a phone. The ideal situation is MacOS for phone development & Linux for embedded development running simultaneously on a single computer. This was very slow on the 13" mac with 4GB RAM & 500Gig of platters. It couldn't run Android developer studio when running XCode.


The day job provided a 15" mac. It was a modern marvel, 2880x1800 display, 16GB of RAM, 1TB of flash, quad core 2.5Ghz, thin as a razor, costing almost as much as a month of rent. To be sure, more powerful laptops for a lot less money exist, but they never lasted more than 6 months & weighed a ton.


Unfortunately, Linux is a long way from supporting the Macbook Pro 11,5. The 13" continues to run the development environment. The main issues were no wifi & no suspend. It will be obsolete before it's ever supported. Attempts to run Linux on a raw partition in a virtual machine have failed. It might work with Linux on a virtual disk, but this would only be temporary.
Posted by Jack Crossfire | Jul 12, 2015 @ 06:03 PM | 3,024 Views


What the day job lacked in money, it had in bluetooth modules, so it was time to whack together a sliding door lock. Of course, the actual bluetooth board was a trade secret. The servo was a 10 year old piece from the DVD robot. The H bridge was the remanes of the laser projector from 2011, which itself was made from the 72Mhz remote control from 2007.


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Posted by Jack Crossfire | Jul 05, 2015 @ 05:15 PM | 2,630 Views




This was the ducks guts for getting stereo with cheap electrets.


July 4 fireworks in San Francisco (3 min 44 sec)



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Posted by Jack Crossfire | Jun 28, 2015 @ 05:13 PM | 2,999 Views
After waking up expecting to see another rocket barely miss a barge or delayed launch, was surprised to see it exploded during liftoff. Of the 3 camera angles, the best one came from NASA TV, then was rereleased with banner ads & annotations.

Falcon 9 explosion from 3 cameras (1 min 13 sec)


The 2nd stage oxygen tank was the scene of many launch delays. Stuck valves, leaky pipes abounded. Not surprising that it finally blew up, probably from a stuck valve.

It's now been 2 consecutive failures in reaching the space station. The last successful mission was April 14. The Soyuz on April 28 failed. The last Cygnus attempt failed on Oct 28, 2014. Only 4 of the last 7 missions made it. The chance of reaching Mars has been better than reaching the space station.

The increasing rate of failures as rocket companies reach ever higher valuations makes you wonder when something has to work to be worth $10 billion & when it just has to be worth $10 billion to prevent a recession.
Posted by Jack Crossfire | Jun 20, 2015 @ 05:45 PM | 2,710 Views




NASA's last space shuttle external tank to complete Endeavour L.A. exhibit

Another win for Calif*. Now only the boosters will be fake, if the exhibit is ever funded. Completion was once envisioned in 2015, then it was 2018, but it was always based on donations & refinancing. If ever delivered, it'll be another spectacle as its transported down the streets of LA. Too bad some water can't be delivered in the tank.


Nearly a year after its inception, the travel fan has been highly successful at defeating the heat. It hasn't chopped any limbs off, hasn't tipped over. Keeping it close & blocking off the area around it has kept kids away from it. Humans are strangely attracted to putting their hands in spinning blades, especially Americans. Limiting the power to 1/4 power has left enough airflow on 12V.

On the downside, it became clear Chinese RC motors aren't capable of running continuously for days. It wasn't long before its RPM fluctuated, then it sometimes stalled & clicked. The bearings failed. Frequent lubrication has kept the bad bearings going.

Also, it's still noisy, despite every effort to silence PWM noise. The commutation noise & shaft resonance are deafening at low RPMs.

The 15 year old squirrel cage blower would make a comeback if not for the fact that it needs to be hosed down with a high pressure nozzle & the outdoor water was shut off.
Posted by Jack Crossfire | Jun 19, 2015 @ 11:33 PM | 2,898 Views
Posted by Jack Crossfire | Jun 18, 2015 @ 01:40 AM | 2,903 Views
Finished it in 32 miles of pounding up & down the trail. The title alone conjured the imagination. Long ago, Carl Segan said one day we would find life on Mars & the martians would be us. The title was obviously a play on that nugget.

It definitely has a few flaws. The mathematical descriptions sometimes get tedious, yet some of his solutions to problems are over simplified & wouldn't really work. It's technical sounding enough to sound like everything is factual. Sounding accurate is what it does better than any other book.

Otherwise, it works. It's easy enough to see how the general direction in the hacking of the various parts could work in real life. It's interesting to see how many different ways the oxygenator & water reclaimer could be basterdized to do virtually any task & to imagine a world where NASA produced stuff that really did work. If the movie is done right, it could invigorate a lot of interest in funding a space program, for a time. A book isn't accessible enough to reach enough people, but a movie might.

There were many attempts to make a movie about traveling to Mars. None got it right, showing how hard the task was. This one might get it right.





In other news, Fitbit finally had their IPO, but more importantly in today's terms, was valued at $4 billion. In creating unlimited free credit, Old Yellen solved the problem of monetizing private data that companies had no right to sell. They would just sell...Continue Reading
Posted by Jack Crossfire | Jun 14, 2015 @ 10:46 PM | 2,948 Views


The decision was finally made to retire the 4 original, low efficiency monocopters & the world's greatest battery charger to the landfill.

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Posted by Jack Crossfire | Jun 13, 2015 @ 01:57 AM | 2,519 Views
Realtime running form feedback

There was the vaporware http://www.runscribe.com/, which claimed to capture running form for viewing at a later time. Fitbit & all the other uprated pedometers captured step rate for viewing at a later time. The trick is none ever provided realtime feedback. They were all intended to gather data for the company to sell to advertizers, not focused on providing any realtime feedback to the user.

A metronome is very good at providing realtime stimulus for step rate. The same thing hasn't been achieved for kinematics. Step 1 is capturing the body positions. Maybe accelerometers or autonomous drones could do it.

Step 2 is stimulating the athlete to adjust positions. A key stimulus would be moving a leg vertically or leaning at the right angle. Maybe pager motors could be strapped to the limbs. Nowadays, they're called "haptics" & worth many billions of dollars. To a child of the 80's, they will always be pager motors. There are also ways of creating brief pushing & pulling forces, by moving weights. Actuators for training body movements could be too heavy.

A kinematic simulating device would allow you to feel how a famous athlete poses. Famous performances could be recorded & played back through the pose stimulators. Reproducing a dance move with subtle pushing forces from actuators might be extremely slow & tedious, but something repetitive like running might be more practical.
Posted by Jack Crossfire | Jun 10, 2015 @ 12:20 AM | 3,347 Views
Posted by Jack Crossfire | Jun 08, 2015 @ 11:44 PM | 3,079 Views






So after running to the Apple store & waiting 30 minutes for a guy to finish with the 5k monitor, it became quite clear that I didn't have enough money to develop a 4k user interface. Had created a mockup to test out asset sizes, based on downloadable screenshots. It was too small on the 5k monitor. The screenshots were for a completely different monitor that the author had no idea of the resolution of.

The original plan was to make assets double the size of a 2.5k monitor, but the downloadable screenshots showed them using 1.5x the size. In the end, 2x size was probably right. Also, instead of making a fully functional interface, it would be best to just mock up a screen with the desired sizes. It's still completely impractical to design a user interface by loading mockups in an Apple store.

The standard resolution of the next generation of monitors will probably be 5k instead of 4k, just as it was previously 2.5k instead of 2k. The extra pixels allow a complete video frame to fit in a user interface. It makes sense when going from 2.5k to 5k to double the asset sizes. It's also much easier than making them 1.5x. It may be necessary to have double size assets for 5k & 1.5x size assets for 4k.

Unfortunately, I grew up in a time when the best monitors consumers could get were $200. Now, the crappiest 4k monitors are $400. The 5k Apple monitor has a $1900 tag & requires also paying for the embedded computer. Paychecks are getting smaller & rent is going up by amounts that would pay for a new 5k monitor every month. It's 1 of those times you realize the limits of mortality. Mortals can't save money or have everything.
Posted by Jack Crossfire | Jun 07, 2015 @ 01:52 AM | 2,994 Views






After much debate, finally built it. The RC fan shroud was noisy & reduced airflow. A screen which allowed air through might do better than cardboard. The motor is still too noisy, so the debate is on about reverting to the larger motor.
Posted by Jack Crossfire | May 31, 2015 @ 09:00 PM | 4,088 Views
Solar powered rover photovore thing:

These were popular, 10 years ago. They have no purpose besides reusing parts. There are some giant electrolytic caps & solar panels are slightly cheaper than the old days. The mane problem is all wheeled vehicles get stuck. There was a ramp up in photovore videos when they were popular, then nothing more to do with them was found.


Bluetooth sliding door lock:

The mechanics are simple, but the encryption is hard. Keyless entry systems have been around forever, but are actually an interesting problem. You can't just send a fixed packet to unlock them. The receiver & transmitter contain a pseudo random number generator which is synchronized. Every unlock command uses a different code from the random number generator. If an unlock command is missed, the receiver tests a certain number of future codes. The receiver can only miss a certain number of commands before it requires resynchronization.
Posted by Jack Crossfire | May 30, 2015 @ 11:45 PM | 3,496 Views



The 1st video card. It was PCI. None of this AGP, PCI-E nonsense. It's not about the performance as much as the memories. It was upgraded to some ghastly amount of memory for its time. The day it was upgraded, there was a geeky old guy in the same room, slobbering over a dual Pentium II he just received. It was the seed for the idea of a dual CPU. In the meantime between then & the dual CPU, this card went from 16 to 24 bit color. What an improvement.


The 2nd video card was for the dual CPU & had a lot of issues. After this came the era of freebie's which lasted until 2006. The next video card will be the 1st one bought since 1999.

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Posted by Jack Crossfire | May 27, 2015 @ 11:17 PM | 3,141 Views



Recycled the last of the through hole components.


After recycling most of 2 old power supplies, it became clear that more through hole components had been reclaimed than would ever be used in the rest of my life, so many parts were left.


The 20 year old Soundblaster had some through hole. A lot of memories came from that card. It was a miracle for a computer to play any amount of PCM audio, in those days. This card still had a muddy sound, compared to the best. It was a rare one which could do full duplex, with enough coaxing.

It only did 44.1khz. Had to upgrade to a new one when 48khz DVD's came along. The 48khz couldn't record higher than -3dB. It gave up a 24khz crystal, which makes the 44.1khz limitation seem like a driver issue. It would never have been replaced if that was known.

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Posted by Jack Crossfire | May 25, 2015 @ 07:18 PM | 2,644 Views





Decided to revive the XV-11 LIDAR, after failing to find a convenient way to wear a sonar transmitter. It wasn't expected to work in daylight. The XV-11 remanes to this day the only 2D ranging device for a comprehensible cost. 4 years of kickstarter projects could do no better. 2 of the LIDAR modules were probably salvageable, with the 3rd taking some doing.

After a year since the XV-11 arrived, it was finally rebuilt & plotting 2D scans as designed. The error rate bottomed out at 250rpm. Below & above, it increased. It depends on stable motor movement as well as speed. The scan resolution is limited to 360 points. You'd get higher resolution scans by sending a fake photo interruptor pattern down the TX line to the photo interruptor pad. Clock it as fast as possible & spin it with a hobby motor being driven in stepper mode.

After building up the software to assemble images & the dual power supply, it was completely useless in sunlight. If the camera got pointed at the sun, it shut down until power cycled. It couldn't detect any surface lit by the sun. In shade, things got more interesting. It could resolve a concrete path, grass on 1 side, & a curb on the other side.


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Posted by Jack Crossfire | May 17, 2015 @ 10:09 PM | 4,480 Views




Fired up a segment of the last sonar circuit, built 3 years ago. Stepped up the voltage to 41V with a 43k 100k parallel resistor network & after a period of fits & starts at 500mA, it ran off 2.5V 100mA just fine. It drove a pulse every 50ms. The voltage hitting the transducer would have been slightly less than 41V.

The next steps are building up a new receiver & recording the waveform on an actual drive. Skepticism keeps progress slow.
Posted by Jack Crossfire | May 16, 2015 @ 02:48 AM | 4,206 Views
It's quite clear that there's not enough time to do any projects at home, anymore. After 3 hours of commuting, the amount of stretching & high vegetable eating required to do all the things this body does consume about all the time.

There's an idea for a monocopter based on a single chip for the radio & computer, with a hacked ESC for silent operation. There's an idea for path following.

Tracking the athlete once again presented a better solution than tracking the path. Sonar presented a better solution than vision, because of the problem of consistent lighting of a target. It would depend on GPS to get the direction of the path. It would use the athlete's position to get the sideways position on the path.

For all the times sonar appeared, it has never worked. The ambient noise on the receiver side is too high. It's too directional. There are too many echos. There aren't any echos outside. The athlete would have to stay in a cone of directionality.

But there are times when staring at a schematic for the day job when you remember staring at schematics as a young boy. They were neat looking drawings of which you knew nothing of the function, only that the collection of lines did something important & better than any human could.

Now, sometimes, you do get paid to stare at the schematics of complete consumer products & know the functions of most of the parts. A lot of livelihoods depend on you to make the once mysterious drawings work, sometimes rework them, sometimes design them. There are still a few mysteries in the analog stages & it's not long term at the rate prices are rising, but for now it's what you want to do, you run along the waterfront every day, you get free lunches, & your boss isn't completely crazy.
Posted by Jack Crossfire | May 14, 2015 @ 11:25 PM | 9,044 Views


So do you feel like an idiot for spending $1400 on a 30" 2560x1600 monitor, 7 years ago? Of course not. The 30" provided $1400 of content. It's going to continue doing so until a system capable of producing 4k video becomes affordable.

Making software look right on a 4k monitor is another matter. For now, it amounts to doubling the font size which looks right on a 2k monitor & hoping for the best. There's also examining the software in the Apple store. These monitors are 3840x2160, only 1.5x the resolution. There's no interest in slowing a program down with dynamically scalable assets.


No-one wonders anymore what technical challenges had to be overcome to make a 4k monitor. They just magically appear from South Korea.