Tricks about LEDs

I recently learned two tricks about LEDs

Trick 1 - Ifr you put current through an LED you get light. What happens if you put light into an LED? Yup, you get current so an LED is also a photodetector. It's pobably not very efficient but if you are looking for a cheap detector an LED might work. You really want to measure voltage since the current won't be very large. My limited experiments show that green LEDs deliver the most voltage (about twice what a red LED will do). the actual voltage depends on the light intensity as well as the specific LED so play around.

Trick 2 - I was working on a broken shaft encoder which used an infrared LED and photodiodes. We wondered if the IR LED was working or not but couldn't tell because our eyes don't see IR. Another guy at the lab wandered past and noted that our phone cameras COULD see IR and sure enough they do detect it and make it visible! Again, some cameras filter IR more than others.

The Three (Interfaith) Amigos

I went to a talk by the Interfaith Amigos who are from the Seattle area. I heard them on KUOW talking about their book and thought seeing them in person would be interesting.

It was great to see representatives of the 3 Abrahamic traditions standing together talking cordially about their faiths and how understanding other's faith helped them deepen their own. They were comfortable enough to learn from other traditions and not be intimidated or defensive.

Their message resonated with me - that God reaches out to people in many ways and whatever works to bring you closer to God and to being a fulfilled human is the best faith for you. A mature faith realizes that what is best for you may not be best for the next person.

In America, our political culture seems so confrontational. It is easy to react with fear to people who are not like 'us' in the way they look or the way they worship. I hope this message that we are worshipping the same God but in different ways is spread.

The Amigos -Rabbi Ted Falcon, Sheikh Jamal Rahman, Pastor Don Mackenzie

Their book -

Getting to the Heart of Interfaith: The Eye-opening, Hope-filled Friendship of a Pastor, a Rabbi and a Sheikh, by the Interfaith Amigos

How leaky is Washington Enhanced Driver License?

I got one of the sleeves that is designed to prevent unauthorized reading of the RFID information in a Washington State EDL. I didn't have an actual EDL or reader so I used my building's physical access card and reader which are also a form of RFID. I tested various materials that might shield the card and impair reading the data.

Basically I held a ruler perpendicular to the reader and slid the card and any shielding along until the reader unlocked the door. I repeated this twice for each setup and got the same reading each time. Here is the data:

Distance Description
(millimeters)

146 Raw card, no shielding
62 Card inside EDL sleeve
146 Card inside mylar anti-static envelope
146 Card inside pink (anti-static) bubblewrap envelope
46 Card wrapped in one layer of aluminum foil
22 Card wrapped in two layers of aluminum foil
52 Card with a single sheet of aluminum foil shielding card (not wrapped)
17 Card inside EDL sleeve, then wrapped in two layers aluminum foil

So you can see that the sleeve does make some difference but means an attacker would need to be closer or have a better antenna. I think I will put any EDL or passport I own inside the official sleeve and THEN wrap two layers of aluminum foil over that.

Caveats: this test might not be as accurate as a real test with a real EDL and reader but it shows relative effectiveness.

Since posting this I found out some more info:

Typical building access cards (prox cards) usually run at 125 kHz, The EDL seems to operate at 13.5 Mhz and now it is quite common to operate RFID in the hundreds of MHz.

For some real science about RFID in passports and Enhanced Driver Licenses, check out the paper at www.rsa.com/rsalabs/node.asp?id=3557

I'm a lumberjack and I'm OK

`We decided to get rid of some of the giant trees in our backyard because they had doubled in size since we bought our home and the needles were killing the grass. Grass should not be crunchy when walk over it.

We got quotes from professional tree folks but Matt and Andrew said they could do the job. We laughed, end of story. Or so I thought.

Then one day I get home from work and Matt has chopped most of the branches off this one tree and he had topped it. Apparently he didn't understand what NO means.


For heavy branches, Matt developed the technique of tying a rope out on the limb he would cut AND tying the same rope on the inside of where he would cut. When he cut the branch the limb would fall but the second knot would stop its fall. Sorry I don't have pictures but I was helping make sure the branches didn't crash.

Here he is cutting a chunk from the trunk. He cuts from the back, then the front, and then just topples the chunk where it lands on the branches acting as padding. 80 pounds * 40 feet is a lot of kinetic energy - you don't want to be under it.


The whole thing took 3 days - 2 days longer than Matt thought but it was very satisfying to have it done. Now all Connie, Andrew and Mark have left to do is cleanup the branches and trunk (20 " diameter!) pieces.

Here is a picture of a cut close to the bottom of the tree. the tree rings are 3/8 - 1/2 inch meaning the tree got wider about an inch a year!
We hope you enjoy this, Ree!




And here is the mighty woodsman! Note the carnage and how the tree is under his feet! Did all that with that little saw, did we?








Whoops! THIS is the brave lumberjack!

Healthcare alternatives

Last night I was thinking of a tiered plan - probably has tons of problems but what plan doesn't?

Here's a 3 tier plan:

Everyone, without exception gets Basic Healthcare for free - and this
has to be as limited as we can - basically preventative medicine and basic care that is cheap at a doctor's office but very expensive at an emergency room. Stuff like prenatal care, colds, flu, TB, possible pandemic stuff we want to keep from spreading, broken bones. Etc.

Then a second tier of healthcare where private plans and the government compete - MRIs, new livers, etc. Not elective but not basic care. Plans could compete on price and coverage.

Tier 3 would be elective stuff - no government plan at this level.

Also one thing that hasn't gotten much coverage - if we insure 47
million more people, we're gonna need more doctors and nurses, clinics, supplies. We'll need to train more people but this is also a boon to employment and
manufacturing.

Finished the Baroque Cycle by Neil Stephenson

A great way to learn history! Read the three books - Quicksilver, The Confusion, The System of the World.

I loved seeing the olde wordes and realizing where so many of our expressions come from.

I took some notes and here they are

page 243 para 2 - the word 'snicked'

page 245 para 1 (and all over the book) - the Mobb aka the Mobile or the Mobility

page 248 para 9 - Neil worked in the expression 'and never expected the Spanish Inquisition'

page 327 para 4 - Neil worked in the expression 'cone of silence'

page 569 para 3 - not sure what he means referring to De Gex and nicotine.

page 602 para 2 - a Dutch ship designer Vroom - thought that was a broomlike creature in Dr. Seuss's On Beyond Zebra.

A note I sent to President Obama

(www.whitehouse.gov)

Dear President Obama,

I want to address the issue of torture. For me it is not an issue of punishing the guilty or making political points. It is getting our country back to the rule of law, sustaining the Constitution, and un-tarnishing our reputation in the world. We've seen how fragile our democracy is and how warped it can become in eight short years.

I urge you to support and press for a non-partisan commission (like the 9/11 Commission) or independent prosecutor to find the truth, assess responsibility, and admit mistakes we made. Then we can move forward as a world leader.

I'm not excited about trials or prison time for the guilty; history will shame those responsible.

I thank God every day that you are our President.

Time for a Third Political Party

Watching all the uproar between Rush and sane Republicans reinforces the thought that the Republicans actually are becoming irrelevant. I think there are millions of people who vote Republican because they have always voted Republican and they haven't noticed that the Republican party has completely changed. They have gone from fiscal conservatives to anything-goes-as-long-as-it-benefits-big-business. They talk small government when it applies to business regulation (that worked pretty well huh?) but have no qualms about prying into your personal life. The party has careened so far to the right that anyone paying attention should see the shift to the dark side.

As the Republicans shrink there is a natural void to fill and that might be where a viable third party could come in. You're probably thinking the Republicans are on the right, Democrats are on the left, so the third party would be centrist. My idea is that the third party must be to the LEFT of Democrats. Let the Democrats run the middle, progressives need their own party and platform. The perceived center has been pulled so far to the right that is is actually where the Republican party was before Regan. Having a Liberal party will serve to yank the center back where it was. Having 3 parties will make governing even more give-and-take but it will give actual power to progressive ideas and Democrats couldn't automatically count on liberal support.

Liberals on the Left Dems in the middle Republicans on the Right

those 3 little words

today I heard those 3 little words I've waited 8 years to hear - "I screwed up."

President Obama said that today about some cabinet choices that had to withdraw. After 8 years of nobody being wrong or able to admit they were responsible, it is change that I've needed to hear. Let's hope for much much more change for the better.

#43 --> #44

President Obama is now the President. George W. Bush stood on the platform and watched as his Presidency quietly ended and Barack's Presidency was quietly started. The peaceful transfer of power is the reason we outlive Communist countries and Monarchies. It is one of the overlooked features of our Constitution so take a moment and appreciate the genius of the men who crafted it.

I was worried that the Bush regime would ignore the elections and the two-term limitation on the Presidency. I was worried that the October surprise would be that a made-up national threat would 'appear' and W would be forced to suspend the elections for our country's safety. I'm breathing a lot easier today.

Constitutional Control System

One of the major methods to control processes and manufacturing plants is the PID controller. PID stands for Proportional, Integral, and Differential control and these terms come right out of calculus and electronics.

The Differential control reacts fast to errors (but might react too much). The Proportional control reacts proportional to the size of the error and is slower than the differential. The slowest is the Integral control which reacts to cumulative errors.

I always thought the checks and balances were like rock-paper-scissors. Now I think our government is similar to a PID controller. The executive branch can react quickly, the Legislative branch ponders issues more than the executive, and the slowest of all is the Judicial.

The analogy isn't perfect but it has helped me think of how well crafted the Constitution is. The founders were very smart and very lucky.

The last 8 years should be a caution to us all of what can happen when our Constitutional control system fails.