Picture Alarm Clock
Lourdes Vandewerker
There are a ton of different Binary clocks on the internet, but this might actually be the first one, made from a strip of colorful addressable LED's, that also features an alarm function and touch buttons, to set things like the time and the color.
Please don't let the complicated look of it scare you away. With a little explanation, reading binary is actually not as hard as it seems. And if you are willing to learn something new, i would like to help you in doing so later on.
This clock is the third version of it's kind. I built a very simple prototype right after the project idea hit me and took it to the Maker Faire in Hannover, to see what people think about it. While i was there, i received a lot of very positive and interesting feedback as well as improvement ideas.
The result of all those ideas and hours of thinking, tinkering and programming, is this rather interesting looking little alarm clock, that has many more features than version 1.0 and today we are going to go through every step of the building process, so you can easily build one yourself.
The first piece we are going to make is the acrylic front panel. We mark where we want our cuts to go, while keeping in mind, that we want a little bit of tolerance for sanding. Then we simply scrape the acrylic with our cutting knife. After we have done that for 10 to 20 times we have a groove. We can then place that grove on the edge of a table and bend the acrylic until it breaks.
After the front panel is cut to size we cut the back panel out of a piece of MDF. We can use our coping saw for this but a cutting knife does also work. We just have to clamp the MDF onto a scrap piece of wood and scrape it with our cutting knife until the blade goes through and we have two individual pieces.
First we drill a 4,5 mm hole into each of the 4 corners. As the acrylic is very brittle and we don't want it to break, we will start with a small drill bit and work our way up until we reach the desired hole diameter. Then we use the template to sand the corners to the right shape.
For now, we can put the front panel aside and stick the second template onto the back panel, where we need to use a 3,5mm drill bit to drill the holes for our 4 pcb standoffs, as well as 4 holes that mark the edges for the little back window.
We then use our coping saw to cut the window out and smooth the edges, with a file. You also don't want to forget to drill the hole for the mini USB cable (I heard of one not so focused maker, that tends to to do such things:D) .
As we are now finished cutting the back panel we can proceed to wrap it in vinyl wrap. We simply cut two pieces to the right size and apply the first one to one side. Then we cut the rims away and free the window. A hair dryer can help to make all of the holes visible again, so we can also cut them out. After doing the same thing for the other side we use our next template and our scrape and break technique to make the little acrylic window for our back panel.
We use our metal cutting scissors to cut a 12,2cm by 8cm piece out of a sheet of metal. Be careful while doing this, as the scissors create very sharp edges. We are going to smooth those with our file and some sandpaper. Then we add our next template to drill holes for the screws and the wires.
First, we cut them into three strips of 6 LED's each. Some of the LED strips come with a very thin adhesive layer or no adhesive at all, so we are going to stick our strips onto a piece of double sided tape and cut it to size with a knife. This will make it stick to the metal plate and, although this is not a professional solution, will insulate the copper pads from the metal surface underneath.
Before we actually stick the strips onto the panel, we clean it with alcohol. While we attach the LED's, we have to make sure that we put them down in the right place as well as in the right direction. The little arrows on the LED strip indicate the direction, in which data travels through the strip.
As you can see in the fifth picture, our data line comes from the top left corner of the panel, goes through the first strip all the way to the right side, than back to the beginning of the following strip on the left and so on. So all of our arrows have to point to the right side.
Let's heat up our soldering ion and put some tin onto the copper pads, as well as onto our wire. The data lines are connected as i just described, while we simply hook the plus and minus pads of the strip up in parallel.
After the strips are wired up, we use our knife to carefully lift the ends of each strip while holding the LED's down, so they still point upwards. Then we put some hot glue underneath to insulate our soldering joints.
After this is done and, we add a few header pins to the wires that go to the PCB. Those wires should be about 16cm long. To be extra sure, that the metal panel is not shorting anything, we use a Multimeter to measure the resistance between all of the pins. If it shows anything above 1kOhm, everything is fine.
To solve this issue, we are going to make ourselves a little light guide. For this we simply cut out another piece of MDF, that has the same size as the front panel. Then we add yet another template to it and drill eighteen 3,5mm holes for the LED's, as well as four 4,5 mm holes for the screws into it. We can then clamp it down to the front panel and use some sandpaper to align the two.
Our frame is supposed to hold the 4 touch buttons, the light sensor and our little speaker in place. Before we can attach them to the frame, we cut a couple of smaller cover pieces out of MDF. We then hot-glue our components onto those covers and add wires to them.
The touch button's power pads are hooked up in parallel, while each output line gets an individual wire. This is also a good moment to test if they are all working. As the light sensor needs 5 Volts on one side, we can simply hook it up to the alarm buttons VCC pad and solder a wire to the other leg.
We use the precision knife to remove pieces of the vinyl, directly above the sensitive areas of our touch modules. With some double sided tape, we can than attach our own buttons to the MDF. I made my buttons out of rubber foam, which gives them a nice, soft texture, but you can use any non-metallic material you want.
We start by placing the components with the lowest profile on the circuit board. The smallest components are the wire bridges, which i remembered a little bit too late, so i started with the resistors. We solder our components in place and move on to the next higher set of components.
Transistors do not really fit the 2,54mm hole spacing of our PCB, so we use our pliers to carefully bend their legs to the shape, shown in the second picture. We first solder one of their legs in place and turn the PCB around. We then reheat the soldering joint and use our finger or a pair of pliers to properly position the component. Now we can solder the other two legs in place.
After all of the small components we solder our Arduino and our real time clock module in place. The RTC module does also not fit the hole spacing that well, so we are only going to equipt the side, that has 7 soldering pads with header pins. We furthermore place some tape underneath it, to prevent any short circuits.
As all of our components are soldered in place, it is now time to make the connections on the other side of the board. For this we are going to take out our non insulated wire. A pair of pliers can be used, to straighten it. Then we cut the wire into smaller pieces and solder it to the PCB.
To make a connection we heat up a soldering joint and insert the wire. We then keep the soldering ion on it, until it reaches the right temperature and the solder encloses it and we get a joint, that looks like the one in the picture. If we don't heat up the wire, we might end up with a cold joint, which would look similar to the other example and does not conduct very well. We can use our wire cutter, to push the wire down while soldering and make sure that the it is laying flat on the PCB. On longer connection paths, we solder it to a single pad every 5 to 6 holes until we reach a corner or the next component.
Making those blank wire connections is quite tricky and takes some skill, so if you are doing this for the first time, it is definitely not a bad idea to practice it on a scrap PCB, before attempting to do it on the real one.
After we are done soldering, we check the connections again and make sure that we did not produce any short circuits. Then we can put the PCB inside the button frame and use it as a reference for the necessary frame wire lengths. We then cut those wires to the right length and add male header pins to them.
All the 5V and ground connections of the touch buttons come together into a 2pin connector, The 4 output wires get a 4pin connector and the light sensor line as well as the two speaker wires merged into a three pin connector. Dont forget to mark one side of each socket and connector with a sharpie, or some tape, so you don't acidentally plug them in the wrong way.
Even though i applied it very carfully, i was unable to get a bubble free result, which is unfortunately clearly visible upon closer inspection. The foil does also not stick to the corners very well, so i can not really recommend this solution.
We start by putting the light guide and the front panel together. After all 4 bolts are in, we align the two panels and then tighten them. A couple of nuts later comes the light panel, where we have to take a look at the direction. The cable should be at the top.
The third piece, is the button frame. Keep in mind that, when looking from the front side, it's speaker should be on the right side of the clock. Pull the cable of your led panel through the middle of the frame, before you fix it in place.
Now we put the front assembly asside and move on to the back panel. In the picture, you can also see my beautiful self made 90 degree mini USB Adapter. I linked you a proper adapter, so you wont have to deal with this kind of mess. You can simply plug your adapter in and run the cable through a hole in the rear panel.
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