1º eso proyecto: lámpara para mesita de noche

Survivor bracelet (pulsera de la supervivencia)

Está pulsera es para hacerla con cordones, aunque uno tiene que ser mucho más largo que otro.

Primero el nudo para hacer la bola que hará de broche, viene explicado aqui:

(Medidas del trozo interior: 68-74 cm)

Cobra Stitch

Arrange the paracord pieces in a "t", with the long, joined piece behind the short piece. The join in the long piece should sit directly beneath the short piece. Here's a big-picture view and a zoomed in view of what I mean:

Now comes a knot called cobra stitch, also known as a Solomon bar or Portuguese sinnet. Whatever you call it, it's pretty straightforward.
First, you take the right arm of the "t" and throw it over to the left - in my case, that's the red strand. Then feed the left (black) strand through the loop made on the right, as the green arrow shows here:

Here's a series of photos to make it clearer. When you tighten the knot, leave about 1" (2.5cm) of loop a the top. Make your knots firm, but not too tight. (Too tight and the bracelet will be stiff and inflexible.)

Then make another cobra stitch that's a mirror image of the first one. For me, that means folding the red strand from left to right, then feeding the right (black) strand behind and through the loop, as shown by the green arrow here. It's exactly what you did for the first cobra stitch, but with left and right reversed.

Just to make it super-duper clear, I've also made a here's a cobra stitch video instructional (opens in new window).
Continue adding more and more cobra stitches, alternating sides. It will always be one color that you fold over the top, and the other color that you tuck behind and through the loop. For me, it's always the red strand that goes over the top, and the black strand that gets tucked behind and goes through the loop.
You can bunch the stitches closer together by holding onto the overhand knot at the bottom of the bracelet, and pushing the cobra stitches up toward the loop at the top. Put something through the loop first (e.g. a ruler), to stop the stitches sliding right off the top. Here's what I mean:

Keep adding cobra stitches until you get to within about 1/2" (1cm) of the granny knot at the bottom. Once you've made all the cobra stitches, your bracelet will look something like this:

Optional: Use needle and thread to fasten the end-most cobra-stitch (red) to the central core of paracord (black), at the position of the green arrow. This stops the cobra-stitches from sliding along the central core, and makes sure that the 1" loop at the end stays the correct size.
Put the bracelet around your wrist and check the fit. Adjust the position of the overhand knot to make the bracelet tighter or looser.

Step 4 - Tidy Up Loose Ends

After checking that your bracelet is the right size, it's time to snip off all the loose ends. You'll have two loose ends from the overhand knot, and two loose ends from the cobra stich.
Pick one loose end to start with. Cut it short, to leave about 1/4" (5 mm) poking out of the bracelet.
Melt this end with a lighter, and press on the molten end with a wet finger (or the flat edge of a knife). This stops it fraying. Also, by pressing on the end, you squash it into a sort of mushroom shape, which stops it working loose. Just be careful not to burn your fingers!
Repeat for the other loose ends.
Here's a picture of one of the molten ends to show you what I mean:

That's it! Your bracelet is finished. Cool huh?

Here are some neat ones made by Alan from the UK:

And here are some two-color ones sent in by reader Liz:

And here's one from Simon, who writes "I'm rockin the crimson and gold this month to celebrate the Marine Corps B-day! The whole thing is a basic cobra knot, but I started by doing two passes with the red, then making those strands part of the core along with the yellow, then simply did the black, and finished up with two more passes of the red. I think it makes a cool transiton between the body of the bracelet and the tie-off, as well as a nice clean two-color core."

Dos de las pulseras hechas x mi:

Friendship bracelet / pulsera de la amistad

De la más sencilla de hacer con 3 hilos y punto triangular:



Para acabar:

The scale of the universe

Awesome animation about the size of things. Scroll your mouse to move between different sizes and click to get information about the size of things.

4º ESO. Proyecto maqueta instalación eléctrica de una vivienda

En el proyecto de clase habrá que realizar una maqueta con la instalación eléctrica de una casa con varios circuitos:

Los circuitos mínimos que deberá llevar:

• 1 base de enchufe.
• 2 bombillas en paralelo que se enciendan con un interruptor.
• 1 bombilla que se pueda encender y apagar desde dos sitios.

Los materiales serán cajas de cartón (cajas de zapatillas), bridas para sujetar al cartón, portabombillas, bombillas, base de enchufes, cables (deberá seguir el convenio de colores) clemas (también llamadas regletas).

De la maqueta y desde una clema saldrá un cable con un enchufe que servirá para comprobar si la instalación se ha hecho correctamente.Antes de enchufar el conector habrá que comprobar que no hay ningún cortocircuito dentro de la instalación.

Se valorará que la maqueta funcione correctamente, que las conexiones estén bien realizadas, la estética y el orden.

Habrá que entregar un informe con un plano de la maqueta con los circuitos así como el esquema unifilar y multifilar de los circuitos:

Fotos de los proyectos:

3º eso. Proyecto semáforo con bote programador

El objetivo del proyecto es la fabricación de un automatismo que controle las luces de un semáforo y para ello nos ayudaremos de un bote programador:

Para que sirva de ayuda nos serviremos de los siguientes videos:

Using a DMM (Digital Multimeter)

Here you have several videos explaining how to use the DMM:

Video 1:


Video 2:


Video 3:


Video 4:


Video 5:


Video 6:


Video 7:


Video 8:


After watching the videos I hope you can understand how to use the multimeter.

Electric Circuits (ENGLISH)

Or better with subtitles here.


Or better with subtitles here.


Or better with subtitles here.


Or better with subtitles here.