Introduction: Trash Landing

Our hackerspace, i3 Detroit, has a bin where people can put their returnable containers so the 10 cent Michigan refund goes to the "pop fund".  It was made from a 33 gallon plastic trash can by cutting a can-size hole in the center of the lid to make it more obvious that it's different from the other bins.  There are many similar-size containers around the shop for garbage, metal, and wood waste, so it's sometimes difficult for people, especially guests and new members to find the returnables bin.  I decided to fix that.

This is a really simple mod that isn't meant to last forever.  The idea was to guide the eye to the hole, so I made it look like airport landing strobes.  The lights flash sequentially in the direction the plane is supposed to land.  These are not the blue lights that line the edges of the taxiways.  These are ahead of the starting edge of the actual landing strip.

You'll need:
- 10 LEDs
- some wire (I used old CAT5 cable)
- an Arduino
- a power pack of some kind with a USB output for the Arduino. 
- two 5-pin pieces of terminal strip that plug into the Arduino connectors

The CAT5 wire is solid, so it won't take a lot of bending, which is why this is more a temporary mod.  If you want to do something more permanent, use a better-quality stranded wire.

Other things you'll need:
- a drill and bits about the same diameter as your LEDs
- a hot glue gun and glue
- a soldering iron and solder
- duct tape (of course!)

Here's a short video of the lid in action:

Step 1: Secure the LEDs

Since the bin is just a plastic trash container with a can-sized hole in the center of the lid, it was easy to mount the LEDs.  Just take a tape measure and find the distance from the edge of the lid to the edge of the center hole in the lid (assuming you've already cut a hole for cans to be dropped through).  Divide that distance by 6, and mark 5 equally spaced points along a straight line from the lid edge to the hole edge.  Start with the first hole 1/2 the distance between holes from the edge.  For example, if the distance is 9 inches, then start 3/4" from the edge of the can, and mark holes every 1.5".  You should end up with the last hole 3/4" from the edge of the center hole.  Repeat this on the other side of the lid, so you end up with two lines of 5 holes on opposite sides of the top (or bottom) of the lid.
Check the diameter of your LEDs.  They are probably either 5mm or 3mm.  Find a drill bit that provides a hole that is a snug fit with the LEDs, so that when you press the LED into the hole it will stay in place.  Drill all 10 holes in the lid.  Use a larger bit, by hand, to ream off any plastic gunk around each hole so that you have a nice clean edge on each.
Insert the LEDs from the bottom side of the lid.  Warm up a hot glue gun and put a glob of hot glue around and over the bottom of each LED.  This will both hold them in place and give them some protection from gunk inside the container.

Step 2: Program the Arduino

Program your Arduino with the code provided.  Note that you need 10 free pins on the Arduino.  I used an UNO.  If you use something else, take a look at the code and modify it if you need to move the pins around.  Note, however, that the pins MUST be sequential and be on the same connector!  Otherwise you'll have a mess trying to build the connector.

Step 3: Wire Everything Up

On the underside of the container lid, determine where you will mount the Arduino.  I put mine in the empty space between the two rows of LEDs.  Since I had a long enough USB power cable, I put the power pack on the opposite side.  Once you've got this figured out, cut two lengths of CAT5 cable that go from the farthest LED on each side to the Arduino.  Make sure to leave an extra couple of inches for stripping, cutting, and routing the cable.  Also cut another length that reaches from the two center-most LEDs to the Arduino.  Allow for routing and stripping.
Strip the wires and solder each pair to one LED.  E.g., solder the solid brown to the anode of the farthest LED on one side and the brown/white wire to that cathode of the same LED.  Then use orange for the next LED, green for the next, and blue for the next.  This isn't set in stone, but just makes it easier to keep track when you're connecting the other ends of the wires.  Repeat for the LEDs on the other side.  You've got two unconnected LEDs left, right?  The two on either side of the center hole.  Use the third hunk of CAT5 to connect the remaining LEDS (pick whatever color pairs that you like).
Solder the solid color wires to the 5-pin connectors in the same order as they are soldered to the LEDs, using one connector for the LEDs on one side of the lid.  I don't recommend soldering with the pins in the Arduio - you could damage the on-board connectors.
Now solder the striped wires together into one big blob (well, something a little neater than that), and then solder a 2" - 3" piece of wire to that.  This jumper wire should be stripped on both ends, since the unsoldered end is going to be plugged into the GND socket.
Now you should be able to plug one connector into pins 2-3-4-5-6 and the other into pins 13-12-11-10-9 with the brown wires connected to pins 2 and 13.  Plug the jumper wire into the GND pin at one end of the digital I/O connectors.

Step 4: Mount Arduino and Power Pack

You should test everything now, before you do the final mounting.  Turn on the power and you should see the LEDs flash from the outer edge to the center.  You can adjust the timing in the code if you like.  Just change the delayMS parameter.

Now just mount the Arduino and power pack with the duct tape.  Make sure you wipe and dry the lid to get good adhesion of the duct tape.  You don't want your Arduino falling into the mess below.  Tape down the wires to minimize the chance they will get bumped or shorted on cans in the bin.  Turn on the power and put the lid on the bin.  That's it!

Here it is in its native setting:
Arduino Challenge

Participated in the
Arduino Challenge