Posts tagged ‘AC’

Progress on an Amp

I was looking for a 4-channel amp to drive a pair of bipole speakers.  For fun, I decided to try to build one.  I bought a broken amp off eBay just for the case for about $30.  In retrospect, I probably should have bought an inexpensive blank case they sell to hobbyists.  At the time, I was intimidated by drilling and tapping a lot of holes in a metal case.  Since then, I have found this to be easy, easier in fact that ripping all the guts out of the old amp.

photophoto (1)

Anyway, I finished the power supply.  The big fat over-sized torroid delivers 35 volts AC to the diode bridges and the smoothing capacitors on the back end, which in turn delivers about 48.5 volts DC for my amp (this measured dead-on the expected 35*sqrt(2)-1 one would expect).  I tried to save some of the old amp's 110V circuitry (such as some filter capacitors).  It had a relay with some sort of delay circuit in parallel with a big resistor as a soft-start mechanism, to prevent a big inrush current.  I could never make it work right, so I replaced it with the poor man's alternative, which is a couple of thermistors that have high resistance cold but quickly heat up and lose their resistance when the power is on.

The capacitors and RC network are in an absolutely beautiful empty board I bought from someone on eBay who etched boards for First Watt kits (an amp series that the designer has generally put into the public domain).  I cribbed the power supply off the design for an F5 amp, though I had to adjust wattage and voltage values to match the voltage I needed.  I spent a week dithering on what capacitors to use -- audiophiles go on an on about capacitors.   Finally, though I am sure all these folks will swear to God they can hear the difference between two brands of capacitor in the power supply, I finally decided I probably would not notice and bought some well-regarded but reasonably priced ones (similar to my approach on that other audio equivalent of wine-snobbery, speaker cables).

What you don't see are two big aluminum heat sinks, which will fill much of the space on either side of the power supply.  The diode bridges and amps will be connected to these.  I have circuits both for a Class A amp, which will need every inch of the cooling, and a class D amp, for which the heat sinks will be an unnecessary overkill.  But they came with the box and I have the space.

CFL Bulbs Suck. However, I Like LED's

A number of years ago, there was a push by many Leftish technocrats for the government to mandate a standardized cell phone power cord.  Beyond demonstrating that there is no personal irritation too trivial for some to demand government action, this would have been an awful idea.  Why?  Because when these demands for action came, cell phone power cords were just that, power.  If a standard cord had been mandated, then current designs that use a USB connection for both data and power would have been illegal, at least without the vendor also putting in a connection for the government standard connector as well.  There is always danger to the government setting arbitrary standards, but these dangers are an order of magnitude higher when the technology is still in flux.

So enter light bulbs.  The government has decided to ban incandescent light bulbs and while not mandating them, it has actively encouraged people to purchase expensive CFL bulbs.  The only problem is that CFL bulbs suck.  The light from them has bad color qualities, many take a long time to warm up, they are hard to dim, and they contain toxic substances.  They also have nothing like the multi-year life we are promised.  I have tried CFL bulbs of many, many brands and none have consistently achieved their promised life.

But as much as I hate CFL's, I am coming to love LED-based lights.  LED lights use even less energy than CFL's and last a really long time.  The technology allows for color tweaking better than CFL's, and already the warm white LED's I am buying (color temperatures around 2900K) are better to my eye than CFL's, and there is no fast-flicker problem that gives some people headaches.  Dimable versions are coming out, and prices are dropping but they are still expensive.   About half my house is LED now, and I am told that landscape lighting is quickly going all LED.

The main cost to LED's is that they all have to have a transformer.  LED's run at low voltages, like 5v, so house current has to be stepped down at every bulb.  LED's in theory should run cool and be cheap, but they are expensive and run hot because of the transformers.

Which leads me to wonder whether we may start wiring houses for 12v in parallel to 110v.  When I grew up, nearly everything I plugged into the wall -- lights, motors, appliances -- ran on 110V.  Now, most everything (other than appliances) that I plug in the wall actually needs 5-12v  (computers, cell phones, all my audio equipment except big amps).  I don't know enough about power lines to know if this is feasible.  I am pretty sure the resistance losses for 12V DC would be too high, so it would have to be 12V AC, but a diode bridge and some capacitors is a hell of a lot smaller and cheaper than a full blown transformer.  I know my landscape lighting has long runs of 12V, that seems to work OK.  It is also a hell of a lot safer to work with.

Every. Single. Time.

Every single time that wind power installations are evaluated based on their actual performance, they turn out to make no economic sense.  Consumer Reports comes to the same conclusion for their wind power trial (and this does not even include the issues of standby power that make even small wind power savings irrelevant to CO2 production).

But if you're considering a wind turbine to supplement your home's power, consider our experience with one product, the Honeywell WT6500 Wind Turbine, a cautionary tale....

A tool on Windtronics' website had calculated we'd get 1,155 kWh per year at the 12-mph average it predicted for our area of Yonkers, New York. And the authorized installer, during his initial visit, didn't say the roof of our headquarters might generate any less, but that rating is at a height of 164 feet, not the 33 feet WindTronics requires for rooftop installations.

In the 15 months since the turbine was installed, though, it has delivered less than 4 kWh—enough only to power a 12,000 btu window air conditioner for one afternoon. A company representative in charge of installations worldwide recently visited our offices and confirmed that our test model was correctly installed. What's more, he told us that while the WT6500 should start generating power at about 3 mph, the initial juice goes just to power the system's inverter, which must be running before it supplies any AC power elsewhere. The true wind speed needed to start producing AC while the inverter is on is 6 mph, not far from the 7.5 mph needed by a traditional gearbox wind turbine....

At the rate the WT6500 is delivering power at our test site, it would take several millennia for the product to pay for itself in savings—not the 56 years it would take even with the 1,155 kWh quote we received.

Hilarious New Study

I would like to think this new study was a joke like that one about the affect of different AC/DC lead singers on decision-making.

The study basically appears to be a transcribed version of some stoner late-night bull session imagining different contact scenarios with aliens.  But one of the conclusions is hilarious.  The Guardian describes the "logic"

It may not rank as the most compelling reason to curb greenhouse gases, but reducing our emissions might just save humanity from a pre-emptive alien attack, scientists claim.

Watching from afar, extraterrestrial beings might view changes in Earth's atmosphere as symptomatic of a civilisation growing out of control – and take drastic action to keep us from becoming a more serious threat, the researchers explain.

This highly speculative scenario is one of several described by scientists at Nasa and Pennsylvania State University that, while considered unlikely, they say could play out were humans and alien life to make contact at some point in the future.

Every time you turn on an incandescent light bulb, ET nukes someone in China.  Or something.  Personally I think it is at least as likely that broadcast copies of Mariah Carey's "Glitter" radiating out from Earth at the speed of light will get us pounded by meteors from space.  More here.

Italian Rail

After having my car hit 3 times in one week driving in Italy, I swore this time I would do it without the car.  So I tried rail.  I had almost as much trouble with rail as with driving.

First, never, ever, ever buy a Eurail pass for Italy.  It is way too expensive compared to the train fares.  Its a good deal in Switzerland, so I bought one for Italy before doing the research.  It became a running joke in Italy - every single Italian rail employee we had to show the pass to told us we should not have bought it.  So not only did I pay too much, but I got reminded of it twice a day.

Second, all but the smallest and shabbiest trains require advanced reservations, but these reservations are nearly impossible to make if you are not Italian, because the rail site has some kind of weird block on most all American credit cards (much about this around the Internet).  This means that I can't just have get-on-the train and go flexibility, I have to pick a train I want to use in the future and then stand in line at a rail station to purchase the ticket or reservation.    Lines do not move fast in Italian rail stations.

But the classic story comes from my minor infraction of rail policy that ended up costing me money.  I don't know if this is just government or if it they have a lot of problem with cheating.  Apparently, each day you are supposed to fill that days date in the next slot on your Eurail pass before you get on the train.  I forgot to on one trip, so the conductor insisted I owed a 50 euro fine.  Seriously.  I said, let me add the date right now, but she said no.  They had a couple guys lined up to throw us off in the next random Italian town if we did not hand over the money  (reminds me of this story in England).

I will say, once I calmed down, that in retrospect the lecture from the Italian state employee on why it is important to follow every single rule and to trust our betters in government that all the rules are for a good reason was almost worth the 50-euro price of admission.

It took me a while to figure out what they were afraid of -- I suppose if you did not write the date in advance, and the conductor never came by, you could get an extra day of travel.  Of course, I had paid extra money for a reservation on that particular train, so it was unlikely I was gaming the system (another reason not to get a Eurail pass in Italy, you still have to pay extra for nearly every train).  And it seemed odd that on a 2-hour train ride they thought it a real risk no conductor would come by, though on the very next day we took a 2-hour ride and there was no conductor, so I suppose it is possible.

In that latter case we were in a car where the AC failed on a hot day, and of course it was the only train we rode on the whole trip where the windows did not open.  No conductor took my ticket, but one did stand at the end of the car the whole trip turning away anyone who wanted to get an open seat in the next car -- after all, we were assigned a specific seat and sitting in another would be against the rules.

Nobel Prize, for sure

Wow, I am not sure how I missed this seminal work, but I discovered it today via Steven Levitt.  The work is titled "On the Efficiency of AC/DC: Bon Scott versus Brian Johnson" by Robert J. Oxoby of the University of Calgary Economics Department. 

Our treatment variable in the experiment was the type of music played while individuals were making their decisions. As demonstrated by Bernardi et al. (2006), different musical styles can have different physiological effects in individuals. These effects, along with emotional responses, may result in different patterns of decision making regarding distributing money between oneself and another. In our Bon Scott treatment, participants listened to "It's a Long Way to the Top" (featuring Bon Scott on vocals) from the album High Voltage. In our Brian Johnson treatment, participants listened to "Shoot to Thrill" (featuring Brian Johnson on vocals) from the album Back in Black....

our analysis suggests that in terms of affecting efficient decision making among listeners, Brian Johnson was a better singer. Our analysis has direct implications for policy and organizational design: when policymakers or employers are engaging in negotiations (or setting up environments in which other parties will negotiate) and are interested in playing the music of AC/DC, they should choose from the band's Brian Johnson era discography.

I have this picture of AC/DC music blasting out on the floor of the Chicago Board of Trade

(the whole story behind this "study" is here)

Contributing to Science

I got to make a real contribution to science this weekend, and I will explain below how you can too.  First, some background.

A while back, Steve McIntyre was playing around with graphing temperature data form the US Historical Climate Network (USHCN).  This is the data that is used in most global warming studies and initializes most climate models.  Every climate station is not in this data base - in fact, only about 20 per state are in the data base, with locations supposedly selected in rural areas less subject to biases over time from urban development (urban areas are hotter, due to pavement and energy use, for reasons unrelated to the greenhouse effect).  The crosses below on the map show each station.

He showed this graph, of the USHCN data for temperature change since 1900 (data corrected for time of day of measurement).  Redder shows measured temperatures have increased since 1900, bluer means they have decreased.
Usgrid80

He mentioned that Tucson was the number one warming site -- you can see it in the deepest red.  My first thought was, "wow, that is right next door to me."   My second thought was "how can Tucson, with a million people, count as rural?"   Scientists who study global warming apply all kinds of computer and statistical tricks to this data, supposedly to weed out measurement biases and problems.  However, a number of folks have been arguing that scientists really need to evaluate biases site by site.  Anthony Watts has taken this idea and created SurfaceStations.org, a site dedicated to surveying and photographing these official USHCN stations.

So, with his guidance, I went down to Tucson to see for myself.  My full report is here, but this is what I found:
Tucson1

The measurement station is in the middle of an asphalt parking lot!  This is against all best practices, and even a layman can see how that would bias measurements high.  Watts finds other problems with the installation from my pictures that I missed, and comments here that it is the worst station he has seen yet.  That, by the way, is the great part about this exercise.  Amateurs like me don't need to be able to judge the installation, they just need to take good pictures that the experts can use to analyze problems.

As a final note on Tucson, during the time period between 1950 and today, when Tucson saw most of this measured temperature increase, the population of Tucson increased from under 200,000 to over 1,000,000.  That's a lot of extra urban heat, in addition to the local effects of this parking lot.

The way that scientists test for anomalies without actually visiting or looking at the sites is to do some statistical checks against other nearby sites.  Two such sites are Mesa and Wickenburg.  Mesa immediately set off alarm bells for me.  Mesa is a suburb of Phoenix, and is often listed among the fastest growing cities in the country.  Sure enough, the Mesa temperature measurements were discontinued in the late 1980's, but surely were biased upwards by urban growth up to that time.

So, I then went to visit Wickenburg.  Though is has been growing of late, Wickenburg would still be considered by most to be a small town.  So perhaps the Wickenburg measurement is without bias?  Well, here is the site:

Wickenburg_facing_sw

That white coffee can looking thing on a pole in the center is the temperature instrument.  Again, we have it surrounded by a sea of black asphalt, but we also have two building walls that reflect heat onto the instrument.  Specs for the USHCN say that instruments should be installed in an open area away from buildings and on natural ground.  Oops.  Oh, and by the way, lets look the other direction...

Wickenburg_facing_se

What are those silver things just behind the unit?  They are the cooling fans for the building's AC.  Basically, all the heat from the building removed by the AC gets dumped out about 25 feet from this temperature measurement.

Remember, these are the few select stations being used to determine how much global warming the US is experiencing.  Pretty scary.  Another example is here.

Believe it or not, for all the work and money spent on global warming, this is something that no one had done -- actually go document these sites to check their quality and potential biases.  And you too can have the satisfaction of contributing to science.  All you need is a camera (a GPS of some sort is also helpful).  I wrote a post with instructions on how to find temperature stations near you and how to document them for science here.

For those interested, my paper on the skeptics' arguments against catastrophic man-made global warming is here.  If that is too long, the 60-second climate skeptic pitch is here.