The components


Click to view the Component symbols

res1.gifThe Resistor

restab1a.gifResistors determine the flow of current in an electrical circuit. Where there is high resistance then the flow of current is small, where the resistance is low the flow of current is large. Resistance, voltage and current are connected in an electrical circuit by Ohm’s Law.
Resistors are too small to have numbers printed on them and so they are marked with a colour of coloured bands. Each colour stands for a number. Three colour bands shows the resistors value in ohms and the fourth shows tolerance. Resistors can never be made to a precise value and the tolerance band (the fourth band) tells us, using a percentage, how close the resistor is to its coded value. The resistor on the left is 4700 ohms.

There is also a resistor display board in each of the manufacturing rooms and on this one there is a close up of a resistor showing the colour code and the inside.

An L.E.D. (Light Emitting Diode)

ld2.gif

ld11.gifLight Emitting Diodes (LED) are very rugged, they last a very long time and they are an optical source. (A LIGHT SOURCE)

LEDs produce red, green, yellow, or orange light. They are used in a range of products.

Can you name any?

LEDs are part of the diode family, consequently they must be connected the right way round or current will not pass through. They are usually protected by a resistor.

This display also shows the LED and give a description, there is also a resistor model which clearly shows the different lengths of the legs. The long one being the positive and a red lead is soldered onto it and the shorter one is the negative and has a black lead soldered onto it. If you look closely at the led you will see a flat part on the side, this is another way of identifying the negative leg if the have been cut.

The Thyristor

A Thyristor (silicon controlled rectifier or SCR) is a little like a transistor. When a small current flows into the GATE (G), this allows a larger current to flow from the ANODE (A) to the CATHODE (C). Even when the current into the gate stops the thyristor continues to allow current to flow from anode to cathode. It latches on.

  • Capacitors
  • 555 Timer:180px-signetics_ne555n.jpgThe 555 timer is an integrated circuit (chip) implementing a variety of timer and multivibrator applications. As of 2003, 1 billion units are manufactured every year.The 555 timer is one of the most popular and versatile integrated circuits ever produced. It includes 23 transistors, 2 diodes and 16 resistors on a silicon chip installed in an 8-pin mini dual-in-line package (DIP-8). The 556 is a 14-pin DIP that combines two 555s on a single chip.
  • Preset variable resistor
  • Pust to make switch.

Information about these will be added later.

One Response

  1. great website guys really help with my revision

    cheers

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