User Manual

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If you do not use a resistor with an LED, then it may well be destroyed almost

immediately, as too much current will flow through, heating it and destroying the

'junction' where the light is produced.

There are two ways to tell which is the positive lead of the LED and which the

negative.

Firstly, the positive lead is longer.

Secondly, where the negative lead enters the body of the LED, there is a flat edge

to the case of the LED.

If you happen to have an LED that has a flat side next to the longer lead, you should

assume that the longer lead is positive.

RESISTORS:

As the name suggests, resistors resist the flow of electricity. The higher the value of

the resistor, the more it resists and the less electrical current will flow through it.

We are going to use this to control how much electricity flows through the LED and

therefore, how brightly it shines.

But first, more about resistors...

The unit of resistance is called the Ohm, which is usually shortened to Ω the Greek

letter Omega. Because an Ohm is a low value of resistance (it doesn't resist much at

all), we also denote the values of resistors in kΩ (1,000 Ω) and MΩ (1,000,000 Ω).

These are called kilo-ohms and mega-ohms.

In this lesson, we are going to use three different values of resistor: 220Ω, 1kΩ and

10kΩ. These resistors all look the same, except that they have different colored

stripes on them. These stripes tell you the value of the resistor.

The resistor color code has three colored stripes and then a gold stripe at one end.