Wednesday, December 26, 2012

Finished Star Clock

Here is the finished Star Clock.  We did a little modification of the code as the 1hz pulsing of the points proved a bit distracting.  It's kind of hard to see in the pictures here, but the points begin as purple and fade over to blue, 1 per minute.  When all five points are blue, the minute hand kicks over another 5 minutes.
A couple of further tweaks are planned, a shift of the clock face itself in color from a.m. to p.m.  With the RTC chosen it's even possible to make the clock change colors on a particular date.  Also completely un-used (except to say Happy Christmas at the moment) is the 16x2 LCD display and navigation buttons mounted on the the back.

Tuesday, December 25, 2012

Making Kirstin's Christmas Gift

One more project to close out the year, a gift for my wife.  She likes things that light up, and I have a "star" theme going this year.  Perusing my favorite electronic supply sites I came upon these Adafruit addressable LED string.  Very similar to a product I'd used in the past (Sparkfun BlinkM) but cheaper, and you don't need to set each unit's address.
It took me a couple of days to work out a concept to take advantage of the lights.  What I would do is to make a clock with the LEDs changing color to indicate the position of the hands.  12 of the LEDs will make up the face, and then 5 additional ones will occupy the points of the star, pulsing to indicate seconds, similar to the way the light on my Macbook Pro pulses while sleeping.

To make the major portion of the clock I used a piece of white delrin plastic.  This part is just slightly smaller than the table travel of the mill.  Additionally both sides of the part need to be machined, which further complicates the setup and fixturing.  To begin, I cut the holes in the back side of the clock to hold the LEDs.  The 12 central holes are for the "hand" display, and the 5 peripheral holes for the pulsing star points.  The large central cavity provides a convenient place to stash the RTC (real time clock) chip which keeps track of date and time with a battery backup.   It will also come in handy for one of the next steps.

In order to cut the front portion I need to hold the part down, as well as know where it is in space, so that the two sides register correctly.  This piece of delrin is cut to engage the central pocket and the "12 o'clock" LED hole.  The large flat areas provide space for the double stick tape.  I machine a lot of things with double sided tape to hold them down, it works very well, even more so when you have boss features like this fixture does to prevent any sideways movement.  

Here is the part placed on the fixture and roughed out.  I wanted the star to have rounded "puffy" look similar to the stars in more modern Mario games.  I almost left the piece the way it looks here, I thought the topographic map effect was rather interesting, but the smoother look won out.  

Here is the finished part.  You can see the outline of the double stick tape used on the fixture block in the background.  The 5 smaller holes in the back will let me mount the control electronics.  

I still need to take a few pictures of the finished product.  The software and colors need a bit of tweaking as well.  More to update soon.