Spectacular Light Show in a Bottle

I have dabbled with fairy lights off and on over the years. I've cut them, soldered them, joined them, connected to USB for power source, etc. This is my latest: a 5 string light show directed by an ATtiny85; I have a triplet and doublet string. The triplet just blinks off and on, the doublet fades in and out. Each set is composed of different colored strings. The first strings I bought were sourced by watch batteries, then I tried using these "cork" batteries. Since I was running out of juice all the time, I decided to source them with USB and have a switch. I want to add remote to the next version.

My project is composed of 7 basic steps:

1: CONSTRUCTION OF THE USB CABLE

2: ASSEMBLY OF THE SWITCH

3: PROJECT BOX

4: UPLOAD OF THE CODE INTO THE ATTINY85

5: PREPARATION OF THE FAIRY LIGHT STRINGS

6: ASSEMBLY OF THE CIRCUIT

7: BOTTLE ASSEMBLY

1: CONSTRUCTION OF THE USB CABLE

I construct my own USB cable since I use so many of them The cost is about 30¢ a cable when I construct my own. Locating the 2 wire cable can prove to be challenging, I finally found some alarm cable at my hardware store. So, strip the 2 ends, and solder each end onto the USB type A male connector. These connectors have polarity, so take care; I always position the wall wart the same, so I will get correct polarity

After soldering, connect the plastic cover; I use super glue to provide more robustness of the USB connectors. It's a good idea at this time to test the cable.

NOTE: You can certainly buy a USB cable already made up, but they are more expenseive.

2: ASSEMBLY OF THE SWITCH

Next, we assemble the switch I am using a very simple switch, just off/on. I use jewelry wire, about 28 gauge because I need a lot of flexibility and something that has a small footprint since we are fitting these assemblies into a very small project box. Omitted from this photo is the shrink tube that I will use in a bit.

I use a Dremel tool to sand down the ends of the wire in preparation for soldering. Be sure you can see the exposed copper on each end.

I cut one pin off the end, and then solder the wire onto the other 2 pins. I then cover with heat shrink since connections are so close, and I don't want to short the switch. Take care with heating the shrink wrap as the solder connections are fragile, and you can "unsolder" the connections pretty easily.

3: PROJECT BOX

This is probably the most time consuming and disliked task of all.(I am in the process of making a jig for the holes, but not there yet.) You'll need 2 cut-out holes: one for the USB, the other for the switch. The switch has a facing which covers the edges of the hole, but the PCB hole is exposed. I cut these with a very hot razor blade. The other hole is round, made with a drill, for the wires to pass thru and easy to drill. The masking tape is a poor man's jig.

4: UPLOAD OF THE CODE INTO THE ATTINY85

We need to upload the code to the µc. Many methods exist for this, and I have tried many, but I still find the Tiny Programmer from Sparkfun the preferred method. If you want to use this programmer, follow the instructions for uploading the correct drivers into your O/S.

Insert the Tiny into the socket of the programmer, and insert the programmer into a USB on your platform where Arduino is loaded.

I would advise that you use the function "BURN BOOTLOADER" in the Arduino tools selection. This doesn't burn a bootloader is yours already is loaded with one, but will modify the fuse for the internal clock. All new µc come preinstalled with 1MhZ clock speed, and we want to replace that option with 8mHz clock. Without replacement, the sketch will run, but slowly.

Next, you may go to github.com/jathomaz/fivefairylites, click the green button to download that into your downloads file. Go into Arduino, select SKETCH on the top menu, select INCLUDE LIBRARY on the dropdown, go to.ZIP library, and find your downloaded file from github. After you select that, you may go to the example code, and upload that.

5: PREPARATION OF THE FAIRY LIGHT STRINGS

Several steps are involved in prepping the fairy lights. The ones I have listed here have a "cork" attached, so the first step is to cut that cork above the first node. We want as long wire as we can get. I advise against unwinding the string at this time.

We now need to strip each wire about 1/8" on the end. I use my trusty Dremel again to strip the pain off the wire ends.

Insert the wires into a breadboard; one wire connected to positive rail, the other, to the negative. If they don't light, switch the wires around. I dab some red fingernail polish on the anaode. Don't tarry with these LEDs inserted with no protection from resistors! Just a minute or two should suffice.

Now, we need to find the right resistor. Hook the DMM up to the string:

1) insert a bare wire in the PB3 column; attach the anode of the DMM to the other end of the wire. Attach the cathode of the DMM to the anode of the lightes, and insert the anode into the negative rail. My first read is about 0.050A, way too high. From experience, I know that 100Ω is about right; we want to insert the resistor in series between the DMM and the string. Now, my meter reads about 0.019A. Just perfect. You can continue with all strings, if you wish, or just use the same size resistor (0.25W) for each.

From experience, I know that 100Ω is about right; we want to insert the resistor in series between the DMM and the string. Now, my meter reads about 0.019A. Just perfect. You can continue with all strings, if you wish, or just use the same size resistor (100Ω/0.25W) for each.

6) ASSEMBLY OF THE CIRCUIT

Okay, now the fun part begins. I used my PCB drawing to help me figure out exactly what goes in which PTH

.

Let's get the USB inserted and soldered first. Then the ATtiny85 socket, or just the ATtiny85 without the socket. After the USB is soldered, you can attach the switch, if you are using one.

NOTE: it's a good idea at this time to plug both ends of the USB in, flip the PCB over, and test the +/- connections on the USB. Be sure you set your DMM to test voltage (DC); you should read about 5Volts. If it does not read 5V and you tested your cable, that means there's a problem with the USB. Do your troubleshooting on it. You can insert your µc at this time and test each pin on the underside as well.

Let's start inserting the resistors. They will be attached to the µc and NOT the big round hole symbols (those are symbols for LEDs). All of the courses on my PCB are on the bottom, so you can't see the connections except on the drawing above.

Since the resistors are NOT polarized, you can insert either of the two ends into the PHT near the ATtiny, stick the other wire end into its paired PTH., solder on the back, and cut the wires.

NOTE: Thread the fairy light thru the round hole on the side of the project box!

Stick the anode (red finger nail polish) of the fairy string into the square PTH, the other end into its paired PTH. Solder the ends. If the USB is still plugged in, you should see action on this one string. If you don't troubleshoot.

Continue with all.

Stuff everything into the project box. CAREFULLY!

7: FINAL ASSEMBLY

Cut a hole in the bottom of a bottle with a drill bit made for glass cutting. I cut a plastic anchor and plug it into the glass, protecting (somewhat) the wires from the glass cut edges. I superglue the plug into the hole.

Now, unwind your strings one at a time, and thread thru this hole. I use a stout piece of wire that has a hook on the end to help pull up the strings to the top.

Hopefully, your soldering will have survived the journey of the string thru the hole, and all will work as expected.

NOTE: bigclivedotcom has an excellent lesson on fairy lights: