Electronics 101 - Part 2

In this series of guides I'll be introducing you to the concepts and practicalities of electronics, and how to use this essential and rewarding skill to add a little something special to your PC. Each part will introduce a few concepts and then a practical project or skill that demonstrates these.

In this part we'll be looking at circuits, how they are wired, prototyped and some of the basic building blocks they are made of.

Concepts

Now that we've learnt what electricity is (in Part 1) we're going to move on and look at how it actually behaves when in a circuit. A circuit is simply a group of components and/or wire with a positive and negative side to allow a voltage to flow.

But which way does electricity flow in a circuit? Well the answer to this is both. When thought of as flowing from positive to negative the term given is Conventional Current, when thought of as flowing from negative to positive the term given is Electron Current. Strictly speaking the latter is more accurate however when following a diagram or building a circuit you should always apply the idea of Conventional Current.

Electricity behaves differently depending how a circuit is connected. Circuits can be connected in three ways. We've included a diagram showing how Voltage and Current is distributed in each arrangement, in each diagram a battery is shown at the top which provides voltage or current and components which use it at the bottom.

Series: This is where two or more components are connected one-after-another. In this arrangement voltage is shared (often unequally) between the components...

...where-as current remains the same for all of them:

Parallel: This is where two or more components are connected side-by-side (or across) each other. In this arrangement voltage remains the same for every component...

...where-as current is shared out as needed:

Series and Parallel: Simply a combination of the two, to predict how electricity will be split or shared in this type of circuit split it up into smaller component groups that are arranged in series or parallel and build up a picture of what's happening.

It's important that you understand these arrangements, we'll be using them to explain how most of the projects we'll be looking at work, but more importantly they'll help get you thinking about electricity in the right way and help you make sense of circuits yourself. How these arrangements affect things practically will be looked at in later parts.
Practical Knowledge

In this parts practical section we'll be looking at how to prototype circuits easily. We'll be looking at two main methods of building a circuit in reality for the hobbyist starting out in electronics, the curiously named breadboard (sometimes called a protoboard) and the more permanent stripboard.

To prototype our circuits, we'll be using a breadboard, this is a plastic block with (usually) 840 holes in it, known as tie-points, components can be easily pushed into these holes. The long rows of holes running down either side of the board, of which there are 4 are called the power rails or the data buses, the rows in the middle of the board have a gap in the middle which allows integrated circuits (or 'chips') to be used in the board. To see how the boards tie pins are connected take a quick look at this diagram, we've marked example connections in blue:

We're going to be using these breadboards a lot throughout the guide, as they are quick and solderless system for assembling and testing the circuits/devices we'll be making, because of this I strongly recommend you purchase one of these inexpensive tools. We got this breadboard from Bowood Electronics (UK), click here to order one.

The other useful prototyping aid is the stripboard, this is a piece of plastic which has a grid of holes which are connected in rows by copper strips on the underside of the board. They come in all sorts of sizes and are very cheap.

Stripboard

Its very easy to see the connections on the strip board, they run in rows across the board connecting rows of holes, components are inserted into these holes and soldered onto the copper strip thus producing a circuit.​

If you could only use one row per group of connections your circuit might get very big indeed, and soldering in IC's (or 'chips') would be impossible. To get around this you can break the copper track on the back of the board to help you lay out your circuit. You can use a very sharp knife or even a screw-driver to break the tracks, but we strongly recommend using a spot faced cutter.​

Spot Faced Cutter

With this tool you can make breaks neatly and quickly, push the tool into a hole where to want to break the track and twist, this will remove the copper and leave a gap in the track...

We'll be using stripboard in later parts of the guide, often transferring a design from the breadboard on to the stripboard for practical use, you can get stripboard in many different sizes as well as spot faced cutters from Bowood Electronics - click here to order some now.

Conclusion

Phew! I think that's enough for this part of our guide. I hope you've enjoyed reading this and have learnt something along the way. Thanks to Bowood Electronics for providing us with the tools and components for this guide, click here to visit their online store and please remember to quote 'PC Review' when ordering.​

Part 3 of 'Electronics 101' will be focusing on how to source power from your PC, two of the building blocks of circuits resistors and LEDs and we'll also be cooking up a little project to put into practice all that we've covered so far.

Until next time, happy soldering!
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