For fun

To spend a good time having fun.

Examen de radioaficionado

A veces pienso que me gustaría escribir un "manual de radioaficionado" en español, porque no he encontrado mucho material por el estilo cuando quería prepararme para el examen de la licencia de radioaficionado española, y creo que al menos la mitad de la diversión inherente en aprender algo está en enseñárselo a otras personas. Aún así, eso sería un trabajo enorme y tardaría mucho tiempo en completarlo. Como de momento no tengo tiempo para ello, de momento he decidido preparar un miniexamen de ejemplo con el tipo de preguntas que podéis encontraros en el examen. Espero que os sea útil.

Examen de radioaficionado

1. En la banda de 10 metros, con modulación de banda lateral única, ¿cuál es el mayor ancho de banda permitido?
  A. 10 metros.
  B. Depende de si la banda es municipal o militar.
  C. Todo el disponible entre "Valencia" e "Islas Canarias".

2. ¿Para cuál de las siguientes funciones no puede utilizar un transistor?
  A. Conmutador.
  B. Mezclador.
  C. Escuchar el fútbol y los toros.

3. Para un transformador con 50 vueltas en el primario y 200 en el secundario, ¿cuál es la razón entre la impedancia de entrada y la de salida?
  A. Es una sinrazón.
  B. Más que cero y menos que infinito.
  C. ¿Por qué nos empeñamos en querer saber la razón, y no dejamos que el transformador haga libremente lo que quiera?

4. ¿Cuál es el límite permitido para las emisiones no deseadas?
  A. Depende de la frecuencia. Por ejemplo, todos los días sería pasarse.
  B. 35 decibelios de día y 30 de noche, medidos con las ventanas cerradas.
  C. Viendo la mierda que echan por la tele todos los días, mayor del que pensaba.

5. Dos personas situadas a 2500 km de distancia quieren comunicarse a mediodía en la cresta del ciclo solar. ¿Qué banda deberían utilizar?
  A. La banda de 2500 km.
  B. La banda de gaitas de la diputación de Ourense.
  C. La banda ancha de Internet.

6. ¿En qué distrito español se engloban las provincias de Barcelona, Girona, Lleida y Tarragona?
  A. El 3.
  B. ¡Número 1! ¡Siempre número 1!
  C. Pregúnteme el año que viene e igual la respuesta le sorprende.

7. ¿Cuál es el patrón de radiación de una antena Yagi de 4 elementos horizontales a 15 metros sobre el nivel del suelo y paralela a éste?
  A. ¿Radiación, dice usted?
  B. Mi madre querida, ¿en serio ha dicho radiación?
  C. Alta ganancia hacia el frente con nulos laterales y una relación de... ¿pero de verdad que ha dicho radiación?

8. ¿Cuál de las siguientes es una buena práctica a emplear con los repetidores?
  A. Decirles que son unos fracasados por repetir curso.
  B. No se me han ocurrido otras opciones graciosas para poner aquí.

9. ¿Qué es la frecuencia crítica?
  A. Una frecuencia que es incapaz de hacer nada propio pero igual opina sobre lo que hacen los demás.
  B. La frecuencia por debajo de la cual uno no se baña suficientemente a menudo.
  C. Probablemente uno de esos programas de tertulia de la radio.

10. ¿De qué se compone el código Morse?
  A. De puntos y rayas.
  B. De pitos y flautas.
  C. De M, O, R, S y E.

I got myself an address stamp

I got myself an address stamp.

My address, stamped once in a piece of paper.

It is fun to use.

My address, stamped several times in a piece of paper.

It is indeed quite fun to use.

Several pieces of paper covered in stampings of my address.

I think I may need to buy a new ink pad soon.

Mystery signal challenge

I'm currently doing some experiments with electronics, and in the process I captured the signal you can find in the attached file. I captured it through my sound card's microphone input, and I've amplified it in software so it's easier to "appreciate". (Update: I've managed to perform a way better capture, so this is as it comes straight from the sound card, with no extra amplification.) Obviously I know what it is, but I'd like to know who among the people who happen to read this will also be able to identify it — and better yet, tell me what's in the signal.

One clue: this signal is produced by something that was invented in 1969.

Post your guesses and comments in the story on Google+.

A brief history of old computers

It is impossible to tell when the first old computer was made because, as it turns out, all computers were new when they were made. Well, except, perhaps, for the original IBM PC, which already looked old back in 1981. Not everyone is of the same opinion, of course: some people say that it’s like the IBM PC had just arrived from the future, since every time you turned it on it would ask what today’s date was.

In the 19th century, Charles Babbage designed several mechanical calculators, one of which, the Analytical Engine, is considered a precursor to modern computers. Babbage approached the British government for funding, but after several years and multiple hearings it was never granted as Babbage was forced to admit that his machine couldn’t run Microsoft Office.

Modern computers are made out of transistors and integrated circuits, but that hasn’t always been the case. For example, in the 40s, electromechanical computers used the same type of relays that were used in telephone switches, and until the 60s, digital computers used vacuum valves. Nowadays, these vacuum valve computers are highly sought after by audiophiles.

Old home computers used audio cassettes to store their software, which could take a very long time to load. Sometimes people would put the wrong tape in the player, and depending on the type of music it could take them up to half an hour to realize their mistake. For a few years, computers could also store data in compact discs, but real enthusiasts preferred vinyl.

In the 80s, home computers could be programmed in the Basic programming language. Nowadays they can be programmed in any of several Complex programming languages.

It is true that old computers were slower than today’s, but they could perfectly do whatever tasks we asked of them at the time. At least right until the moment we used someone’s new computer and our old one suddenly became unacceptably slow.

I’ll finish this piece with an example that illustrates how technology has become more important and influential in our lives: in 1952 a UNIVAC computer was able to successfully predict the result of the US presidential election, and nowadays voting computers can determine the result of the presidential election. Who knows what the future may bring us?

(Comments in the Google+ post.)

A brief history of computer networking

Since time immemorial, humans have sought to connect their computers to exchange knowledge and to improve the mutual understanding of humankind. Of course, what they actually did with that was exchange porn, mostly.

A precursor to the computer networks was the telegraphy system, developed during the 19th century. It had many applications: apart from sending and receiving messages, you could buy and sell stocks, do money transfers, and other things that we think are so modern that we can do over the Internet nowadays. They didn’t have any need for an equivalent to Instagram, though, because back then all photos already looked vintage.

Computers were invented in the 40s, and they were so big and expensive that an entire University might have only one. To connect it to other computers, which could be thousands of miles away, they used telephone lines. As more computers were built and installed, new computer interconnect technologies were invented, because the computers kept calling each other and tying up the lines, and when the operators tried to get them to hang up they would complain: "but daaaad, I’m talking with Stacey, this is super important, you don’t understand me, I hate you."

The Internet became popular in the 90s. People expected that an ubiquitous global computer network would serve to exchange knowledge and improve the mutual understanding of humankind. Of course, in the end this marvel of human engineering and international cooperation was used to exchange cat pictures and porn, mostly.

At the end of the 90s someone said in passing, “hey, in the 19th century they had wireless telegraphy, why don’t we have wireless networking now?”, and some electrical engineers were so embarrassed by it that they went and invented Wi-Fi and then pretended it had existed all along.

Nowadays, thanks to digital convergence, we treat everything as just data, so our usages of the different communications networks are very mixed up. For example, we connect to the Internet at home through cable TV, browse the web on our phones, do phone calls on our laptops and watch TV over the Internet. At this pace things will become more and more mixed up and we’ll eventually do weird stuff like listening to music on the radio. Time will tell.

(Post your comments in the accompanying Google+ post.)

A brief history of time travel

Sometimes a thing is discovered or invented by several people at the same time. It happened to calculus, and it happened to the telephone. A theory says that those inventions or discoveries happen when the right set of circumstances align and the time is ripe. The time machine is another example of this: it was invented simultaneously in the years 8583, 6383, 4725, 3174, 1997, and 47 B.C.

Continue reading to see a full account of the history of time travel, all the way from the end to the beginning.

A brief history of personal computing

People think that personal computing is something completely new, and that PDAs, smartphones, and the like are recent inventions. However, the history of humankind is very long, and there are ancient precursors to very modern things. For example, since the dawn of time, humans have used their fingers to count, add, and subtract numbers, which is a clear example of digital computing. In addition, the ancient Sumerians are renowned for using tablets to write and do their bookkeeping, and the Romans used a stylus to write on a small handheld pad.

1-star Amazon reviews

0 of 70 people found the following review helpful
Shallow and pedantic, October 12, 2011
By Captain Munch (Oregon) - See all my reviews
This review is from: Doritos Tortilla Chips, Nacho Cheese, 11 Ounce (Grocery)
This is the worst book I've ever read. The plot is linear and predictable, the characters are flat, and the setting is badly researched. Apparently this is the author's first novel-length book. Hopefully it will be the last.

14 of 14 people found the following review helpful
They are HEAVY!, January 3, 2013
By Bargain Hunter - See all my reviews
This review is from: Vinyl Dumbbells 10lb - Pair (Misc.)
Today I was sitting in my rocking chair at the porch when Pat the mailman arrived, and he gave me a very dirty look as he handed me my Amazon package. I soon found out the reason: this item is HEAVY! No really! It had to weigh at least 20 pounds! No wonder Pat was so grumpy.

I think Amazon should give you a warning or something, it is very irresponsible of them to sell such heavy things without telling you beforehand.

235 of 392 people found the following review helpful
It's OK, but..., March 24, 2009
By Alice Wonders (Nevada) - See all my reviews
This review is from: Dremel 4000 Rotary Tool (Tools & Home Improvement)
I received this Dremel brand rotary tool today. It works really well. Only giving it 4 stars because the box it came in was a bit scuffed in a corner.

UPDATE 1-12-2013: Reduced to 1 star because it broke down after only four years of continuous use grinding granite and titanium alloys. You'd think Dremel would make better tools.

89 of 92 people found the following review helpful
The author didn't research the subject, April 2, 2013
By Natalie Blood (New Jersey) - See all my reviews
This review is from: Dracula by Bram Stoker (Hardcover)
Almost as soon as you pick up the book you know that it's going to be bad. The characters spend the whole book writing letters to each other and there's no action to speak of.

There are lots of anachronisms. For example, it is set in the 1800s but Mina types her letters and Dr. Steward records his voice. Hello! Everybody knows that there were no computers in the 1800s! Can you be more stupider than that?

Also, the book gets everything wrong about vampires. I think the author should have done some reading on the subject before writing the book.

(Post your comments on Google+.)

Simetría lateral

Un experimento fácil de hacer para el que tenga un poco de familiaridad con software de retoque fotográfico:

  1. Sacaos una foto de vuestra cara, completamente de frente;
  2. recortadla a lo largo del eje vertical de vuestra cara y separadla en dos mitades;
  3. para cada mitad, hacedle una copia e invertidla de derecha a izquierda (como un espejo);
  4. pegad cada mitad a su correspondiente copia invertida, formando así dos caras.

Nadie tiene la cara completamente simétrica, así que los resultados suelen ser interesantes.

Tengo una foto de los resultados con mi cara.

Si alguna vez me van a clonar usando de ejemplo una foto de un lado de mi cara, ya sé qué lado quiero que usen. Uno de estos dos macizos tiene una gran carrera en el mundo del cine. El otro es John Cleese cuando aún no tenía bigote.

El Día de la Independencia

Este lunes es el cuatro de julio, que es cuando aquí en los EEUU celebran su “Día de la Independencia”. El Día de la Independencia es el día en que todos los chavales que hayan cumplido los dieciocho años y, por lo tanto, sean legalmente adultos, abandonan el hogar paterno y se independizan.

Seguro que habéis visto esta tradición decenas de veces, ya que es el inicio de montones de películas americanas: el campus de la Universidad lleno de recién llegados pisando todo el césped, y los coches dando vueltas alrededor de un macizo con el escudo de la Universidad, hasta que la cámara se acerca a un coche que se detiene y, por pura casualidad, consigue aparcar en el mejor sitio de todo el campus y sin necesidad de hacer maniobras. Un chaval se baja del coche y mira con asombro y un poco de aprensión toda la fauna y flora que le rodea, y su padre, que es judío y lleva gafas, le da un abrazo lateral, estrechándole los hombros, y le dice: “¡bueno, por fin estamos aquí!” Y, por si no quedaba claro, añade: “¡la universidad!”

La escena que esas películas no muestran es cuando, esa noche, los padres llegan a casa, y se dan cuenta de que por fin están solos, y de que pueden hacer lo que quieran, donde quieran, y cuantas veces quieran. Y de tanta alegría que les entra, lanzan fuegos artificiales, y los vecinos se reunen a admirarlos. Cada año, entre cuatro y seis millones de personas cumplen los 18, así que, como os podéis imaginar, el cuatro de julio hay un montón de fuegos artificiales...