My first electronics project – Deck Lighting

12 Jan

Wow. This is actually really cool. I need lights to put inside the deck I’m building and thought it would be cooler and cheaper if I did it myself.

Firstly, it must be said that there is a thing called a “hack-space”. It’s a shelter for nerds, geeks, artists and any combination of the three, to gather and support each other. Not in a Nerds Anonymous way, but to help each with projects, all chip in for new equipment, have a place to leave junk that you can raid, etc.

So I’m affiliated with a Sydney based hack-space called Robots And Dinosaurs, which is rad. There’s a lot of knowledgable people there and they helped me a couple of days ago to put together my first circuit containing electronic components. I learned how to solder onto a board, use a prototyping board, how to wire up components and how to do formulas that apparently mean stuff.

The very next night, I took the components home and wired them all up and the circuit didn’t work. I gotta say, I’m a little disappointed. I expected to be an electronics genius after one lesson. Anyway, I have had offers of help to work out why it’s not going and this is the reason for this post.

First things first, planning. The following photo is a page from my moleskine where we worked out all the numbers and did diagrams and so on. Any one reading this, I’m happy for you to point out errors, but it must be said that we got this all working on the prototyping board, so I’m thinking the maths is good.

So, as I said we got it working on the prototyping board and it was all good. All three LEDs lit up enough to walk around the back yard in darkness. I did not buy any extra stuff and I didn’t have any other gear at home.

When I got home, I thought about it and realised that I wanted the lights spaced out. I decided then that I should connect up the circuit using wires instead of using a board. So I grabbed some left over good quality speaker wire and used that to wire the circuit up.

I also decided to use connectors to make sure they were solidly in place, but so I could remove them once I’d tested it and seen how bright they were in situ. The above picture shows how I have connected them. What it doesn’t clearly show is that the cable has two wires initially joined together (I split them and taped them up to prevent pulling on the connection). The positive wire is square in shape and the negative is round. This makes them easy to tell apart, but also easy to hide away. I connected the positive to the positive leg and negative to the negative leg. I also then put each end of the wires on to two batteries held together so I could test everything was fine.

The final circuit looks like this on the ground.

There’s not much detail, but you can see it’s all connected. Also, don’t be put off by the LEDs glowing, that’s just the reflection of the camera flash.

To give more detail, here is a close up of where the power source and resistor are all connected.

Now keeping in mind that this worked perfectly on the prototyping board, I was a bit sad it didn’t light up. I have placed it on my dining table (on top of a towel) and pulled the multimeter out… I discovered that if you try to check how much resistance there is through the LEDs they actually glow a little. This at least meant that they were connected fine and that they work. Below are the three LEDs being tested.

Then I checked the resistor is working. It is a 120 ohm resistor and therefore should have a resistance of around 120 ohms.

Then I worried about the way these banked connectors would work. Therefore I put one of the tips of the multimeter on one end and the other on the alternative end. It was still all good.

And then since everything else is working, it is probably the battery pack, right? Wrong. Here’s the proof.

The only thing that seems a little out of place is the slightly higher than 12 v reading. I’m not sure if it’s enough to throw out the resistor, but a) I don’t know why it worked before then, and b) I can get a new resistor if needed.

So I’m asking for thoughts, comments and suggestions. I need to get this up and running pretty damn quick.

I will also post the solution and how I went about fixing it.

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Posted by on January 12, 2012 in Decking [COMPLETE], Electronics


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