午夜福利1000集合

What you need
As previous weeks, plus:
Jumper wires
An electronics breadboard

YOU can find yourself drowning in wires as your circuits get more elaborate. To add components without making an octopus, you need a .

Breadboards are so called because early makers literally used to on wooden boards used for cutting bread. The modern version is a neat way to connect lots of parts and rapidly alter your design.

It is essentially a slab of plastic punctured by tiny holes. The holes are electrical contacts. In every numbered row, all the holes are connected, but each row is independent. The columns on the long sides, called rails, are between blue and red lines. Like the rows, their holes are connected, but each rail is independent.

Take an LED and slot its legs into the holes so that it is standing in two different rows. Have one end of your resistor share a row with one of the LED legs, so that they are connected, and put the other end in a row by itself.

Now the LED and the resistor should each have one lonely leg in a different row. Use wires to link one row to the blue rail and one to the red. But which way round?

The red and blue rails will be your connections to the terminals of the battery. The colours are there to remind you which is which. You will be connecting a wire from the red/positive battery terminal to any hole in the red rail, and attaching the negative side to the blue rail. But hold off for now 鈥� it is a good habit to add the battery last.

In Electric candle, we learned that the LED鈥檚 longer leg is positive, so this end should connect to the red rail. Now attach the battery and watch the LED light up.

Time to make it a bit more sophisticated. Take three LEDs, say red, yellow and green if you have them. Stick them in , each straddling two rows, and give each one a resistor. Make three connections to the red power rail, one for each LED and resistor combination. Instead of attaching the three remaining lonely legs to the blue rail, connect each to a different bit of wire that has a tinfoil square at the end. Use more wire to connect a single, long piece of tinfoil to the blue rail.

Now you have a sequence of switches. Tap one of the three foil squares to the foil strip and a single LED will light up. Stick it on your desk to let people know how busy you are: red for 鈥渃ome back later鈥�, yellow for 鈥渕aybe鈥� and green for 鈥淚鈥檓 free鈥�.

There are plenty more ways to combine components. You could have guests rate their stay at your house by lighting up between one and five LEDs, for example. Or, if you make one per person, you could use them as scorecards.

To download a printable version of this page click here

Thanks to Imperial College Advanced Hackspace for use of their facilities

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What you will need next week

DC motor (9-volt compatible)

Plastic bottle

Straws, wooden skewers

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Next in the series

1 Introduction

2 Electric candle

3 Toast notifier

4 Desktop traffic light

5 Propeller car: Get things moving with a motor

6 Magic eight ball

7 Theremin

8 Sound-sensitive disco ball

9 Rubbish sweeper

10 Biscuit bot

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