First off, let's talk about the possible safety concerns here

• It is easy to burn yourself with the soldering iron.
• Ingesting lead is always undesirable.
• Flux fumes are an irritant and long-term exposure can be harmful.

To mitigate these risks, you should take the following precautions:

• Be careful when handling the iron and anything that has recently contacted it
• Wear gloves and/or wash your hands thoroughly after soldering
• Don't inhale the cloud of smoke; ask for more ventilation if it is problematic

There are many, many, many guides on how to solder out on the internet nowadays. We'll provide some instructions here, as well as links to some other good resources in case those are more usable for you.

1. Clean off the tip of the iron by rolling it on a sponge.
   • If it doesn't sizzle, it isn't hot enough to use yet.
2. “Tin” the iron by touching the end of the iron to the solder just a bit
   • The point is to make it easier to conduct heat to the metal components
3. Hold the iron at the junction of the pad and the lead you're soldering so that both heat up
   • Count to 3 if you're not sure of the timing
4. Touch the junction point with the end of the solder, feeding in a few mm worth of material
   • Surface tension from the solder will form a cusp from the pad to the wire
5. Remove the iron and evaluate the connection
   • It is always better to heat too little than too much. Too little can be fixed with more heat. Too much might just damage something

Sparkfun video guide

PDF printout of soldering guide

====== Warming up ======

Instead of starting out right away with the final board, let's practice a little with something smaller scale.

===== The Fidget Blinker =====

This little thing serves no useful function, but you can move the wire around to make things light up. Joy!

TBD

• Start by plugging in the soldering iron and waiting a good 3 minutes or so. It takes a while for it to heat up enough to be capable of melting the solder.

• Put a resistor aligned vertically on the board, as shown. It should have a 3-hole span between the two legs.
• Insert a pair of LEDs diagonally through the holes a few spaces up from the resistor.
  • Make sure the longer legs are further away from the resistor here! Direction matters!
• Solder the resistor legs in place.

• Bend one of the resistor legs to make sure it can make contact with the LED leads

• Solder the two LED legs closer to the resistor in place, then bend the leads downwards as shown.

• Bend the other legs upwards, and then solder them at the base

• Finally, solder the other pair of legs together.

If you connect the positive lead of your battery pack to the LED legs and the negative to the resistor, you can bend the floating resistor leg back and forth to light up the LEDs.

If you wish, there is a Raw video of the board construction. It is a half-hour of running commentary as the snowflake PCB is populated, and the sound may be a bit quiet. Note that the ordering of instructions has now changed to make assembly easier.

Prepare your board by inserting 560 $\Omega$ (the ones with green, blue, brown, and gold bands) resistors into the holes labeled for R1, R2, R3, R4, R5, and R6.

• Solder the resistors in place one at a time, trimming the leads as you go
  • Be careful, and hold your hand over the leads to keep them from flying across the room!

Take the other four resistors 10k$\Omega$ (the ones with the brown, black, orange, and gold bands) and solder them into the R7 - R10 locations

Place the 555 timer chip in the IC1 spot

• Make sure that the dot on the chip lines up with the dot on the board! If you're not sure, ask!
• Solder two opposing corners in place, then check to make sure the chip is flush with the board's surface
• Finish off the remaining 6 pins
  • If you make a mistake, don't panic! Stop for a minute, get help, or move on to another part temporarily. About the only damage that can't be fixed is overheating parts.

Place the shift register in the 14-pin IC2 spot

• Check that the half moon on the chip lines up with the board
• Again, tack the corners, check the chip, and then finish the rest.

Place the small capacitor C1 into its place and solder it

Take the larger electrolytic cap (red and white) and place it in the C2 hole

• Careful! This capacitor is directional. Make sure that the long leg matches up with the + sign on the board

Take the diode (black cylinder with a bar on one end) and place it in the D7 spot.

• Make sure the band is oriented in the same way as the image in the board!

Take your transistor and carefully bend the middle leg forwards (towards the curved side) a bit. Place it in the location marked T1

* Make sure the flat side matches the image on the board!

Take the wire terminal and place it in the square above the diode. The edge with the buttons should be next to the diode.

Lastly, place your LEDs in the locations at the board's corners

• Make sure to match the long leg to the long soldering pad!
  • The LEDs can be placed on either side of the board, so you can have a clean-er looking snowflake or show off all the circuitry

With all that finished, place your batteries in their holder with the + side upwards. Take the wire closest to the switch and insert it into the left side of the terminal while pushing down the button. It should stay put when you let go. Put the other wire in the other side, flip the switch, and hopefully have everything light up!

There are a couple ways you can display your board.

• You can loop some thread or ribbon through the holes to hang it off of something.
• You can put it on one of our laser cut easels.
• You can just let it sit there and blink on your desk!

Now that the board is finished, it's time for a little cleanup. We'll use some isopropyl alcohol (IPA) to clean off the flux and any excess shmoo.

• Just use the spray bottle (sparingly!) to apply some IPA to the board's solder connections
• Gently use a Kimwipe to clean up excess liquid before letting the rest evaporate

The batteries are CR2032 coin cells, and they should last you quite a few hours. After they die, you have a few options:

1. Replace them with new batteries.
2. Buy a AA/AAA battery holder. Something like this that holds four batteries will be sufficient.
3. If you have a Raspberry Pi or Arduino, you can use the 5V and ground connections to power the board
4. If you are more adventurous, you can get a USB breakout board and connect the 5V and Ground leads to the snowflake.
   • We take no responsibility if you connect anything wrong and fry your usb port!

There are five functional parts of this circuit, each of which is made from a handful of components

A spring terminal is used to connect wires from our power supply (a pair of coin cell batteries) to the rest of the circuit. Without a voltage source, nothing happens. To keep us from damaging the chips if we attach the wires backwards, a diode is put in series with one of the connections to stop unwanted currents.

The small Integrated Circuit (IC) is a dedicated chip known as a 555 timer. It repeatedly charges and discharges the larger capacitor at a rate determined by the nearby resistors. With the parts we've got, it comes out to putting out a clock signal once a second or so

The larger IC is a 74HC164 chip, known as a shift register. It has a series of 8 outputs, and whenever there is a clock signal, it “shifts” the value of the 8th pin to the 7th, the 7th to the 6th, and so forth until it sets the first pin to the same value as the input.

We use a single transistor along with a pair of resistors to produce a NOT Gate. It's purpose is to output 0V when given 5V in, and 5V when given 0V. It essentially inverts the value given to it.

There are 6 LEDs, each in series with a resistor. They are attached to the first six outputs of the shift register on one end, and to ground (through a resistor) on the other. The resistors keep them from drawing too much current and damaging themselves.

When you turn the power on, the clock will start counting. We've attached the last output of the shift register to the NOT gate, and then use that as the input to the shift register. This means that the shift register will start setting outputs to 5V each time it gets a new clock pulse, until it reaches the last one. At that point, the NOT gate will change the input to 0V, and the lights will go out in sequence. And then it repeats. Forever!