This post is mainly going to discuss how I have started my projects like my LED sky, 5x5x5 RGB cube (Currently does not exist because it was squished flat on the party...) etc.
Let's use the LED sky as our example :
When you want to do a project you need an IDEA!! No idea no project. I got my idea from a local mall that had a huge ceiling with bunch of LED's in it that were glowing like stars. Normally I did even consider that as my future project but I decided to do it when my sister said that shed like something like that.
So as a "good brother" I started doing some ideas; firstly I considered doing it with arduino which was my main source of ideas and projects. I designed few shields that I would etch in my school, but just before i decided to make them I consulted my teacher from Digital Logic who gave me idea to consider using 8-bit shift register 74199N which depending on how you connect it could make bnch of led's glow in different order, so I figured it would me much much cheaper than using my one and only arduino I had, since i can't really buy arduinos so easily. So the 1st point is, ALWAYS, but always consult other people that could improve your design and reduce even the cost of your projects, I had my teacher, but you, you have the whole Element14 community!, use that!
This project could be placed in the category of medium-hard projects, but not for the complexity to assemble it, but to learn how the logic behind the chip works so you can use that to the maximum. What I'm trying to say is that you should always learn and research before you start doing something, if you spend just that much more time on learning you will save hours and hours of troubleshooting after if your circuit does not work.
First I settled down to try and make the circuit in MultiSim 12, which is a EWB (electronics workbench) program in which you can test your designs and see if and how they work (I highly recommend it). After about few days trying how and why it works I made the schematic :
As you can see it is a load of mess!! I didn't even make the right power connections (instead of using the correct VCC and GND connectors I used troughole pins as power which does not connect with the hidden power pins on the 74199 - you can see that there is no VCC and GND on the chip)
Next I try to make the PCB (just used auto route) :
The first problem is that the routes are going behind the connectors for LED groups (connectors are just LED,s on the PCB), second problem it isn't very well designed, and because of the faulty power connections in the schematic the power for the chips was not connected and I did not notice it.
Then I was eager to etch the PCB in my school. When I came and asked my teacher if I can do it he said that we didn't have any more etching solution (I was kinda devastated), and it was only a few days before Christmas and I really wanted to make this in time for my sister so she could open it on Christmas eve ( we always open presents on Christmas eve for some random reason).
I knew I had no choice but to make my own PCB on a piece of perforated board. So I started wiring up and ended up with this mess :
And you guessed it, it DID NOT work! After a few hours of troubleshooting I did fix something but it turns out some LED's light up brighter than the others, then with the multimeter I figured that some outputs from the chip gave around 2.5 and some 3.5 volts maximum. And also the board was working at certain angles because the wires were loosely attached.
So I went and made a yet another board :
You can see that this board is much nicer than the previous one and it actually worked. So then i had to wire up the sky itself(it was a PAIN IN THE BUTT to wire all of the LED's up) :
And I was pleasantly surprised when I found out that it actually works! :
The led's are wired up in this princible
Where each colour represents the different groups of led's (e.g. red - A, orange - B etc.)
When you set the chip to light the led's in an specific order you get the illusion of them glowing randomly.
So this was just dos and do nots of when making projects.
In conclusion :
- Always start with a detailed plan, do your research thoroughly
- When creating schematics and PCB's TAKE YOUR TIME, there is nothing worse than figuring you made one connection wrong and when you make the PCB you figure that you have to start all over again
- When wiring try to imagine different scenarios (layouts) in which you can connect stuff
- Don't start with ultra ultra hard projects, if you have never done any projects I recommend you to start with a simple 555 timer in astable mode, fun circuit that blinks 2 LED's.
I hope you enjoyed my little bog post of my endeavours to succeed at this project in reasonably small margin of time.
If you have any question leave them in the comments section below I will gladly answer them, and if you liked this post like it
In the end we added just a bit paint :