Beginning Electronics - Building a simple alarm


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Although it must be nearly 50 years ago now, I can remember visiting my older cousin's "radio shack" like it was yesterday. He had recently finished his stint as a radio operator in the RAF and had brought his skills of radio construction and communication home with him to 'civvy' street.

His radio shack was actually a shed in the garden to which he'd been exiled by his long-suffering mum after one solder burn on his bedroom carpet too many. He motioned to me to sit down while we both listened on the radio to someone with a marked Texan drawl explaining how the weather had been this summer. My cousin leaned forward and flicked a switch on the radio. "Roger, Hank. This is Golf Three Romeo Oscar Uniform here in England wishing you all the best 'til next time." My cousin was actually speaking to him! I was certain I could feel the electricity crackling in the air in the shack!

My cousin turned to his workbench and showed me his latest radio he was building. Not only was he talking with people all over the world, he was building the radio equipment himself! He showed me some of the basics, such as how to make a soldered connection, and I was hooked for life. One thing I have always found particularly fascinating is that, even though there are relatively only a few different types of components, give two people the same handful of components and they will produce something completely different.

Even with just four different types of components, resistors, capacitors, inductors and semi-conductors, it's possible to build anything from a plant-waterer to a sophisticated house alarm or from a mobile phone to a space shuttle! - well not quite but you get the idea!

Getting Started

Things have moved on since those early days - transistors and integrated circuits have largely replaced valves (vacuum tubes) and, although the principles remain the same, construction methods have changed drastically. Gone are the heavy metal chassis and individual point-to-point wiring to be replaced with other techniques such as the printed circuit board.

As with most hobbies, the best way of learning is by doing - any theory can come as it's requred. Again, as with most hobbies, it's better to start with a simple project so progressing will be fun instead of hard work. Let's begin our journey into electronics by building a simple burglar alarm for the garden shed or your push bike.


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