Intro: Half-moon Clock With Arduino
It can be difficult to keep track of time. Sometimes clocks show the wrong time, sometimes they don't run at all. Analog clocks which use a digital "heart" can be very hard to find. This clock (hopefully) solves those problems. Arduinos are very precise and can even give you the exact time since it started in milliseconds. I used the arduino UNO as the (non-beating)heart for this project. The clock can be as big or small as you like, the hand can be decorated in any way you like, and it is completely customizable.
Step 1: The Main Frame
Using the compass draw two half circles on the 5mm balsa. Draw another smaller half circle inside one of the circles, so that it looks like an arch. Cut out the arch and also the half circle and sand the edges. Cut out two small 5mm balsa rods, and glue them onto the arch and half circle like in picture 3. Use two scrap pieces of balsa to support the area near the glued rod when the glue is drying. Cut a small hole in the balsa to put the servo in later, and make sure the servo arm mount is roughly where the spike of the compass was when you drew the circle. Also, put a mark on the arch every fifteen degrees. These will be where the clock numbers will go. Cut two small squares and glue them onto the bottom of the balsa rods. These will be the feet.
Step 2: The Servo Mount
Cut out a piece of 2mm plywood with a small rectangle big enough for the servo to sit in. Cut two small supports that are big enough so that when the servo is put in the mount the mount will be low enough that the white part will just stick out the top.
Step 3: The Led Mount
Start with a small rectangle of 2mm plywood and make a small hole in the middle. Push the bulb of the led through the hole, bending the wires flat against the wood as you do so. Make another slightly larger rectangle, making a hole in this one as well, and then glue it to the other rectangle with the led still poking through both holes. Trim the excess plywood. Continue like this until the top of the led is roughly flush with the plywood. Glue two small supports to the back of the led mount. Glue another piece of plywood to the back, and once again cut off the excess. Sand the mount. Solder two longer wires onto the led leads, and put heat shrink tube over the solder connections.
Step 4: The Clock Hand
Get a piece of 5mm rectangular balsa wood and cut it in half like picture 1. Create a channel in each half of the wood, wide enough that the wires will get through if you put both halves together with the wires in between. Remember to make one end of each channel thicker to accomodate the heat shrink. Put the two halves together with the wires in between them, and glue them back together. In the end it should look like picture 3. Make the end towards the led slightly thinner, like a clock hand and sand it all down. Cut a small alcove at one end for the servo arm(trim the servo arm slightly) and glue it on, making sure that the servo arm is in such a position that the led mount will be hidden by the clock arch when it is all put together. Trim the last bit of excess wood off.
Step 5: Sorting Everything Out.
Cut a small hole where the screw should go on the servo mount and thread the clock hand wires through it. Solder a low resistance resistor(it doesn't matter which level of resistance) to the black wire on the led. You can paint the clock if you want. Number the small marks you made earlier from one to twelve. There will be one too many. number the thirteenth number 1 and number them from one to twelve the opposite way as well. Attach the servo to pin 11, and the led to pin 13. Upload the code below, set the clock hand to one, and in one hour it should have moved from one to two. At 13:00 your time, set the clock hand at one(on the left) and it should start keeping time. you are done! if you liked this instructable then look at some of my others(if you want).