Electronic project: DIY electronic clock

Most of the previous tutorials here have been Arduino related, but there are much more than just Arduino when it comes to making things.

Connecting projects on a breadboard is a simple and fast way to prototype but when you want to keep your project for a long time or present it on some kind of contest or even sell it online, you have to actually build it in a more sophisticated manner.

The best way to keep your connection safe and clean is to make a PCB. We are not going to cover topics of designing a PCB in this tutorial, we will simply show you the practical skill that you may need to build your projects from the ground up.

Soldering! Soldering is a very useful skill which you will almost all the time need when bringing electronic parts together to form a functional whole. We will extensively solder in this session.

Ok, without further due, let’s dive into the project.

We will use the parts below.

You can buy this kit here.

Here are some tools we are going to use to assemble the electronic parts.

  • Soldering iron
  • Tin
  • Scissors to cut out longer legs of elements
  • Tweezers
  • Solder sucker

Before we start doing anything, I would like to throw these few pieces of advice:

  • Small components first! It is much easier to put small components when you have plenty of space, it is also easier to solder them. This is very important when you solder SMD components but in this project, we do not have any SMD components so don’t worry
  • First, solder and then cut the legs of components, if you do it before soldering there is big chance you will make them too short and then you will have a problem
  • Use a vise to hold your PCB in place
  • Double check polarities of the components and their placement
  • Check if there are no shorts before connecting to power
  • Be careful because the soldering iron is very hot so you can easily burn your skin with it!

Here is our PCB.

The labeling on the PCB will be very useful when identifying where each of the elements will go.

As I said early,  start with small components so let’s start with the capacitors.

Those are ceramic capacitors so they don’t have a polarity but they are of 2 different values. Above 30pF are on the PCB and here is the last one (slightly bigger than those 2 above).

Mount the resistors, to bend the legs of the resistors, use tweezers.

Here are all of the components you should have on the PCB at this point.

Before soldering these, we will add the electrolytic capacitor, this time around the polarity is very important.

As you can see in the image below, there is a silver strip on the side of the capacitor and that is the negative pin. The other one is the positive one. That’s how you should place it on the PCB.

Now we can put our PCB in a vise

Heat up your soldering iron to about 280 degrees Celsius and gently touch the leg and the pad around this leg on the PCB. Hold it like that for few seconds.

Then grab your tin and put it on the other side of the leg that you want to solder. Try not to touch the tip of your soldering iron with the solder wire. Since we have been heating the component’s leg for a while, it should be hot enough to melt enough wire into the contact. That’s the best way to solder. We do not want the tin to stick to the tip of the iron.

Soldering this board isn’t so simple because there is a small amount of copper around the pads so don’t worry if you can’t get perfect solder.

Now, you can cut out the legs of the components

Here is how it should look now

Pretty cool, isn’t it?

And here is the top side.

It’s time to place more components on the board: the buttons, the buzzer, and the transistor. There is only one way to place the buttons, but check the polarity of the buzzer (there is + on the sticker and on the PCB), the transistor should be as the symbol on the schematic

Here, everything is soldered.

It’s time for the black long part with a dot, as you can see the dot is on the left and this is important.

Next, let’s add the socket for the microcontroller.

Last two parts we have to add are: the battery connector (blue with screws) and the display.

Solder everything, cut out the legs and you will have this:

Before connecting to power, let’s put the microcontroller and buttons in place

When connecting the battery to the power terminal, check the polarity. the ground terminal is on the left and 3V to 6V on the right

It’s working!

Congratulations you’ve just finished the DIY clock project.


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