About Me

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I previously worked on Virtual Reality and other hardware at Valve.  I currently work at Google[x].

Prior to starting at Valve, I built computer peripherals such as keyboards, mice, and joysticks that were designed to be used inside MRI machines.  My company, Mag Design and Engineering, sold these devices directly to researchers at academic institutions who used them to publish scientific papers in peer-reviewed journals.

After work, I spend time on many different types of projects that usually involve circuit design, machining, material selection, and general fabrication/hacking.  My favorite place to be is my home workshop.

ben dot krasnow at gmail

http://www.youtube.com/user/bkraz333

http://www.linkedin.com/pub/ben-krasnow/4/6a9/679

http://www.twitter.com/BenKrasnow

Wednesday, September 29, 2010

AES tops DMV as most-aggravating government entity

*rant*

If you ship a package internationally, and the contents are valued at $2500 or more, you are legally obligated to record your shipment with AES (automated export system). This is true for all shipments -- personal, small business, corporate, etc. OK, so no problem if recording the export were easy. Unfortunately, AES is the most backward, bureaucratic, aggravating, and time-wasting entity that I have ever dealt with as a business owner.

I first must register online with AES and create an account (understandable, but still a turn-off. Since the data is ostensibly for census, it could be reported for each transaction without knowing the sender's intimate details). Oops, my old AES account from years ago is no longer active and I cannot create another account with the same name. How can I reactive the old one? The only way is to fill out a paper form and fax it to AES. No online form, no phone call. It must be a fax, and then I have to wait for someone from AES to call me. OK, fine, that's done. Now I can enter my shipment details, right? Nope, my original AES account was registered with my social security number. AES doesn't used SS numbers anymore. I must apply for an EIN (employer identification number) from the IRS. OK, luckily the IRS has an online form, and it "only" takes 10 minutes. OK, now am I ready? Nope, the AES account must be "transitioned" from the old SS number to the new EIN number. I first must create another AES account to administrate the change from the original SS to the new EIN accounts. Meanwhile every time I create a new account with AES (new password for old account, admin account and new account), I must create a 12-character password with six non-repeating characters, numbers, and special characters that does not contain any dictionary words. The form conveniently offers to print out your password since their is no hope of remembering such a thing. Great security. Tell users to print their password -- on a networked printer?!

After registering my original account, I had to study for a quiz. That's right, a quiz. AES will not let users enter shipment details until they pass a quiz. Can you imagine FedEx requiring customers to pass a quiz so they can ship packages online? Good grief! OK, finally, I have my EIN account setup, quiz passed, etc, etc. It's a good thing I did this in preparation for a large transaction that I will have coming up in the next few months. My account will work in November, right? No, actually the 12-character password must be changed once every sixty days or else the account is suspended. How do I re-enable it? A fax. Yes, the only way to re-activate the account after 60 days of disuse is to send another fax and wait for a call back. Holy Hell!

OK, I've got my account reactivated, everything is in place, and I am ready to enter shipment details. Here we go. The form is divided into seven parts, and each part has about 15 fields. Some of the fields are easy, like my name. Some of the fields require me to determine the "schedule B or HTS number" for the items in my shipment. These numbering systems attempt to codify all commodities in the world. And since this is a US government system, you can be sure it is updated to reflect the latest technology and trends. Searching the HTS for meaningful product designations can easily take 30 minutes. It's also very unlikely that a first-time user would choose an HTS number that is even remotely correct. The AES included schedule B search engine is truly an insult to all search engines: "spaces are not allowed in search queries."

So basically, it's going to take between 2 hours and half a work day to simply record the package details with AES. I hope the package will not be going to Canada. There is an exception for packages shipped to Canada, but then a NAFTA form must be filled out.

Anyway, I've pretty much vented enough. Here are some various approaches to the situation:

1. Charge international customers more, or raise prices generally to account for the additional time wasting that AES causes.

2. Refuse international orders.

3. Split shipments into packages that are each valued at $2500 or less. This might be illegal, but I am not sure.

4. Ship international packages with the US Postal System and enter the correct (over $2500) value, but then choose "NO EEI 30.37a", which indicates the value is less than $2500. For some strange reason the system will accept it, and I have never heard of people having problems shipping stuff this way. The system might depend on USPS clerks checking the value manually, and they never do this because they are almost always overwhelmed by handling an international shipment.

5. Lie about the value, so that it is less than $2500.

Tuesday, September 28, 2010

Seriously hacked central air conditioning

In my old rental house, I had a large window air conditioner mounted in a window in my living room. It did a great job blowing cold air, but was ugly and noisy (as are all window air conditioners). When I moved to my new house, the need for air conditioning was a little lower since the new house has double-pane windows and the house is also shaded by trees. However, I play music with my band every week in one of the small bedrooms, and with six people in one room in the summer, the need for air conditioning is easy to grasp. I didn't want to mount the large window air conditioner in a window, since it is so big and ugly, so I mounted it in the house's crawl space and installed flexible ducting to connect it to the house.

I know it is very difficult to see anything in this picture; the crawlspace is very dark and cramped. The air conditioner is an LG 15,000 BTU/hr model. It's the largest LG model that runs on 120V. I modified it by adding standard register boots to its cold-side inlet and outlet. I also used a plastic storage bin to couple the inlet register boot to the evaporator coil. Everything is sealed with rubber foam gaskets. Currently, the hot-side inlet and outlet are not connected to anything and just vent into the crawlspace under the house. I know this is pretty dumb, so my plan is to connect the hot-side outlet (the back of the air conditioner) to some nearby crawlspace vents. I can use uninsulated flex duct for this.

I removed the unit's control panel and built some custom circuitry that allows me to control the device via the standard wall-mount thermostat in the house.

The inlet and outlet flex duct are 8" and travel up from the crawlspace in a utility closet that is open to the house's attic. In the attic, the return duct connects to a 14"x6" ceiling vent:

14"x6" return vent


The supply duct connects to an 8" inline duct fan that is mounted in the attic:
http://www.tjernlund.com/retail/fans.htm
$130 shipped, new on eBay. This particular fan is very powerful and also very quiet. I was able to mount it to the ceiling joists, and it cannot be heard over the general air noise when the system is running. I originally tested the system without the duct fan, but the air conditioner's stock fan did not move enough air through the ducts to be useful.


10"x6" supply register

Another 10"x6" supply register


Yesterday, it was over 92*F according to this thermometer. It was 81*F inside my garage.


Ahhh, 70*F in the house!

I had just installed the new duct fan and was curious to see how well it worked, so I turned the thermostat way down and was pleased to see the system had plenty of cooling power. The house is only 1100 ft^2, so the 15,000 BTU/hr air conditioner is sized well. The supply air is just under 20*F cooler than the return air, which indicates a properly-sized system.

Today, I set the thermostat for 75*, and the system was able to hold that temperature while running between %25 and %50 (the thermostat uses "four cycles per hour"). It was about 92* today as well.

Retrofitting Ikea cabinet door dampers to old Ikea cabinets and non-Ikea cabinets

I recently went to Ikea to buy a new cabinet, and noticed that all of their display models now have these soft-close dampers that prevent the cabinet door from slamming. The damper catches the door as it closes, and allows it only to close the last couple inches very slowly. Ikea sells the door dampers ("Integral Door Damper" 2/$4.99) separately from the cabinets. I wondered if the dampers could be adapted to my existing Ikea cabinets. I bought some and found that old-style Ikea hinges can easily be modified to accomodate the dampers.

Left: Old-style Ikea hinge Center: New-style Ikea hinge Right: Door damper

Note that the hole between the adjustment screws in the new hinge is very rectangular, while the hole in the old-style hinge is rounded. The door damper needs to mount in a rectangular hole.
Less than one minute with a Dremel and 1/8" carbide die grinder bit made the hole in the old hinge much more rectangular.

The door damper snaps into the rectangular hole and works perfectly.


Next, I thought that I might be able to use the door dampers for non-Ikea cabinets and also Ikea cabinets that do not use the standard 125* hinge.

I started by making some mounting brackets out of shelving support rod. This stuff shows up in every hardware store. I used a milling machine to cut the pattern out, but it would certainly be possible to use a dremel. The large rectangular hole matches the size of the hole in Ikea's hinges.Next, I mounted the bracket to the interior of the cabinet with two screws. The top-side of this particular cabinet would not allow such mounting, so I mounted it on the bottom.

Snap the door damper into place, and voila! The door now closes silently. This method would work for nearly any kind of cabinet. The dampers cost only $2.50/each from Ikea, and the homemade mounting brackets are even less expensive.

Friday, September 17, 2010

Time delay for relay (turn-on delay)

http://www.circuitdb.com/show.php?cid=92

When power is applied to this circuit, the relay will not activate until a few seconds have elapsed. The parts count is very low and the circuit does not need external or regulated voltage. I used the circuit by keeping the 12V connected at all times, and switching the ground connection. Still works fine. Circuit will turn off very quickly after power is removed, but a rapid off/on cycle will have a shorter delay than expected because of residual charge in the cap. Not a big deal in most cases, though.

Wednesday, September 15, 2010

Visa gift card (credit card)

I recently participated in a usability study and was given a Visa gift card to thank me for my time. Unfortunately, the gift card is not as easy to use as cash or a check, but I found a good way to handle it.

The gift card cannot be used at an ATM or bank to get cash. If you try to charge more than the card's balance at a merchant, the entire transaction will be denied. A merchant cannot check the card's balance. So, if someone receives a Visa gift card, uses it a few times, then wants to use all of the remaining balance, he or she has to check the balance by calling an 800 number or going to a website, then go to a merchant and say "Please charge eg $23.14 to my gift card and I'll pay the remainder with another credit card." If the amount charged to the gift card is even 1 cent over the balance, the transaction will be denied. Also, the card's balance will deduct by $2 every month ("maintenance" fee), so you'd better check your balance on the exact day you plan to use it. I guess this fee only applies 13 months after the card was purchased, so not quite as brutal, but the card's value simply disappears after 2 years.

As you can see, Visa must be making a lot of money on unused balance, maintenance fees, and the $5.95 that the gift card's purchaser spent just to burden you with this pseudo money. Here's how to beat the system: Pay your utility bill with the gift card. As soon as you get the gift card, use it to pay the card's full value into your phone, cable, etc account. The utility company will just credit your account, and lower the amount due for the next month or two. This way, you can use the full amount of the card without ever checking balances or worrying about fees. Now spend your utility bill money on something fun.

Monday, September 13, 2010

Comcast internet

Comcast cable internet is cheaper and much faster than AT&T DSL in the SF Bay Area. Here's the comparison:


AT&T DSL. $33/month plus basic phone line charges of about $12/month. 2.5 Mbit down / 0.42 Mbit up.


Comcast Internet 15/3 plan: $19.99/month (even for new customers who are not buying TV or phone). 17 Mbit (average 15 ) down, 5 Mbit up.


Here's what I learned:

Do not call Comcast's phone number. Instead, use their online chat feature. It seems the people in the call center are unable or less willing to make a deal than the chat room people.

Each CSR (rep) acts as his or her own negotiator. They all have different quotas and desire/ability to make deals. Start a chat session and just ask for current promos. If nothing sounds good, refuse politely and try again in a few minutes/hours/days. Different reps will offer different deals.

In one chat session, I mentioned that I currently had AT&T DSL. A few minutes later, the Comcast rep offered me cable internet for $33/month. What a coincidence! That's exactly what I was already paying for DSL. The reps have more information than I thought. The rep would not go lower than $33/month and I eventually refused.

Buy your own cable modem. eg http://homestore.cisco.com/viewproduct.htm?productId=54377589
For $30 or less, you can beat the $5/month rental pretty fast.



The "internet-only" service apparently comes with some basic cable TV channels:

I do not want cable TV service (even for free), but I brought in my shop monitor from the garage to test if cable TV was indeed available. It appears so. The Comcast tech did not install any sort of filter between my house and the poll. I flipped through it, and it appeared to be all working. The only thing that caught my eye was an old Star Trek The Next Generation episode. I will return the TV to the garage and not even worry about "stealing" cable TV.



Here's a photo of a device that the Comcast tech called a "trap." It's not a trap in the electrical sense. It's more of a mechanical security device.

The tech left it on the ground after completing my installation, so I decided to cut it open to see its internals.

If this were a 1/4" left-handed drill bit, it might grab the inner piece of metal enough to turn it counter-clockwise.

Remote focus control for telescope (remote follow focus)

The chips in the control circuit are:

Avago HCTL-2032-SC quadrature decoder
E-lab EDE1200 stepper control
Generic 558 timer for simple oscillator








Hi-res version


Moon at f/6.3 1/320 at ISO100. The lens is approx 1260mm (telescope with focal reducer).



Composite shot of Jupiter with its moons.

Monday, September 6, 2010

Terrestrial photography with a telescope and DSLR

I setup my 8" Celstron Nexstar with f/6.3 focal reducer and Lumix GH1 to try out some "terrestrial" photography. I picked a public road in Redwood City, CA that has a good view and easy parking nearby. As far as I know this is a public sidewalk here.

Here is a shot with the GH1's stock lens at 14mm. The red squares indicate areas that I will image with the telescope.

Here's the stock lens zoomed all the way out to 140mm. This area is centered on the left red box in the first image.

This image was taken through the telescope and f/6.3 redcuer, so it is effectively 1260mm f/6.3.


This image was taken through the telescope at prime focus 2000mm f/10. Note that with the GH1 crop factor, the field of view here is comparable to 4000mm in standard 35mm SLR terms. Most of the blurriness is coming from air currents and haze. I will try again on a cool, overcast day, and I would expect better resolution. I am also eagerly awaiting my telescope remote-focus project to be completed. It's extremely difficult to achieve perfect focus while touching the telescope's focus knob, so it's possible this photo was taken slightly out of focus.



The distance is about 2.4 miles.



Here is a cluster of antenna across the Bay.

22 miles.

Here's another post of photos that I took many years ago with the same telescope and a Nikon 35mm film camera.
http://benkrasnow.blogspot.com/2009/09/telescope-magnification.html

I forgot that I even had an eyepiece projection adapter. I'll try it out next time, but I suspect the limiting factor will be air clarity not the telescope optics.

Sunday, September 5, 2010

Web-controlled watering can and vortex tube

UPDATE: Code added at the bottom of this post.


This is an interactive art project that I have been building for an upcoming exhibition. The idea for a web-controlled watering can come from the first "iphone watering can" that I helped build with a friend for Maker Faire a couple years ago. Search the internet/youtube for "iphone watering can" for details.





This new version uses a different drive mechanism and a PD control loop to make the watering can track the desired position in realtime. The interface works with any webkit browser. My collaborator and I have discussed using the iphone or android accelerometers to achieve control through phone tilting. I'm not sure if the tilt data is available to the web browser, though, and we are trying to make the interface run on as many platforms as possible. Any ideas?

The siteplayer webserver is extremely old technology and has many problems, but does work. I would explore using a hacked WRT router in the future for similar projects.






HTML file from Siteplayer webserver:
http://www.magconcept.com/watering/can.htm.txt

SPI file from Siteplayer webserver (simply to establish a server response):
http://www.magconcept.com/watering/serial.spi

Arduino code to get serial data from webserver and effect the PID control loop
http://www.magconcept.com/watering/watering_can.pde

Friday, September 3, 2010

Youtube speed and partner program

I have a couple questions for anyone reading this:

1. Does ATT DSL suck? I live in the SF Bay Area, and the speed on youtube is often acceptible, but 720p sometimes has problems playing and even 480p sometimes has problems because of limited bandwidth. 1080p never works smoothly. I am fairly certain the the DSL link itself is not the problem because while a video is paused due to lack of data, I can go to other websites in other browser windows, or even run a DSL speed test and get decent speed. So, it seems that either youtube itself is slow, or ATT has a crappy connection to youtube servers, or is actively throttling bandwidth. Look at this (http://www.youtube.com/my_speed)

My ISP is AT&T, and I have 3 Mbit DSL. I am not sure why youtube doesn't have any view data for me personally. It might have something to do with firefox privacy settings or Adblock Plus. In any case, this looks really disappointing. It makes me want to sign up for Comcast. What are your thoughts?


2. Is the Youtube partner program (revenue sharing) worthwhile? After my last blog post ran on hackaday (attracting a couple thousand views to my video), youtube invited me to become a partner. At first I thought that I would definitely do it, but now I think I might pass. When I started to create an AdSense account, the signup page looked all messed up. At that point I realized Adblock Plus was preventing my browser from loading the css for the entire page. I think it would be a little hypocritical to force ads on other people, while I myself hate them with a passion. I am thinking the world has enough advertisements, and the amount of money that I could make from these videos is probably very small. Youtube will not disclose how much they pay, and after searching the net, I found that youtube partners are not allowed to tell other people how much they make or what the pricing structure is. How insecure is youtube that they don't want anyone to know how much money is to be made? If there were a lot to be made, surly they would want to advertise the fact?

Feel free to leave an anonymous comment.