Minty Time – Make It

Yay! Time to get started making it! But before we get stuck in, let’s check we have what we need …

Preparation

A table / desk or place to work with access to a power outlet where you can solder safely and good light. It makes a difference.

You also need to print out the Drill Template (v2, v4).

There are also a couple of overall principles that are useful to remember:

1. Square pads are ground. We sometimes call these square holes, but of course it is the hole pad that is square, not the hole itself.
2. Something is always the limiting constraint. In this case, it is the height of the Altoids tin. There is a lot of space in the tin horizontally, but the vertical space – the height of the tin – is limited. So when connecting the circuit board to the lid, be sure to snug it right up agains the LEDs. If you are using a non-Altoids tin, make sure it is at least as thick as an Altoids tin.
3. Red wire goes to power, black wire goes to ground. This is a good rule, so stick with it for all projects. Don’t use red or black wire for other connections.

Parts list

None of these tools are included. If you do not have them, now would be a good time to buy / borrow them. Radio shack is a good place if you are in a hurry, as well as many online dealers. I provide some links to online places as well. These tools are pretty useful to have around the house and for any electronics project.

sheet

Image	Description
	Soldering Iron. Try to avoid a very cheap one, which will be more trouble than it is worth. The one in this picture has a temperature control knob and costs about $20.If you do not know how to solder you should read one of the many tutorials online, for example here.
	Solder. Rosin core 60/40. Bad solder can lead to a lot of hard to track down problems, so don’t cheap out.This is sold at Radio Shack and your local hardware store, amongst other places.
	Desoldering tool. A solder sucker is useful if you are prone to making mistakes.
	Multimeter. The old faithful. One with a continuity setting is especially useful to “ring out” circuits. The continuity test symbol on your meter usually looks like this or like this.
	Stand. Not strictly required, but it makes soldering the parts together a lot easier. If you are going to be doing more than one project, this is a worthwhile investment.This stand pictured is a Panavise Jr Mini, a good choice. The cheapest price seems to be Hobby Inc (currently $20.29), but Amazon sell it as well (currently $20.99) and it’s eligible for Super Saver shipping.
	Wire Strippers. The switches and batteries are connected with regular wire, so we need a way to strip it. You can cut wire with this as well, or use a separate wire cutter, which is probably easier.
	Brad Point drill bit. For drilling the holes in the Altoids tin we need a 3/16ths bit. If you use a regular twist bit, it is very difficult to drill the holes accurately, so a brad point (aka Lip and Spur) bit is strongly recommended. Because our eyes pick up if rows of things are out of alignment easily, a twist bit (&wonky holes) will affect the final appearance a lot. Amazon sell these individually, but it’s cheaper to buy it as part of a set at Lowe’s, Home Depot or your local store.
	A scrap block of wood. Because the Altoids tin is very thin, we need a base when marking and drilling the holes. Pretty much any old piece of wood wil do. A small piece of 1×1 that fits inside the lid is perfect.
	Any smallish nail or brad will do – this one happens to be an aluminum roofing nail. This is for marking the holes in the tin using the downloadable template. You can also use a nail set if you have one, but a nail seems to work slightly better.
	A hammer. This is used to mark the lid with the roofing nail. You will need to hit quite softly, so a smaller hammer is better – in fact, you can just push on the nail if you have to, or use the block of wood.
No Picture right now. Here is one from Sears.	While it is not required, either a drill press or a Dremel press is recommended.

Batteries, Template and Altoids tin

You also need a regular sized Altoids tin and the template for drilling holes  (v2, v4), plus two AAA batteries.

MintyTime Kit

You also need the contents of the MintyTime Kit, available from Wicked Device. Everything listed below is included in the kit – please check your kit when you get it, and email support@wickeddevice.com if there are any problems.

Image	Description
	A 74HC595 Shift register. These are amazing little IC’s. They have been around for ages, and are really useful when you start to run out of pins on your Arduino or ATTiny. The Arduino ShiftOut tutorial uses them.
	An ATTiny 2313 with the MintyTime software burned onto the chip. Available from Wicked Device.
	Green, Red and Orange 3mm LED’s, for a total of 14 LEDs: One for the seconds heartbeat, seven for the minutes and six for the hours.
	LED mounting sockets. These come in a variety of options from many suppliers, and each one is slightly different. You want to make sure to get the one’s which let the LED’s protrude somewhat, otherwise they will be harder to see. We use Newark #09J9214.
	14 current limiting pull down 470 Ohm resistors for the LED’s. They prevent the LEDs from getting too much current and running the battery flat.
	Two small pushbutton switches. Although this switch has 4 pins, they are paired, so there are only 2 terminals. You want to solder wires across the terminals. To test which two are connected, use the continuity setting on your meter two test two pins at random. For the correct pins, the meter should only buzz when you push the switch down. The continuity test setting on your meter looks like this or like this.
	Light Dependent resistor (LDR), AKA Photocell, photoresistor.
	Flexible wire. At the time of writing, the wire to connect the switches is white.
	2xAAA Battery Pack. It is also possible to use a “wall wart” to power the chip, or use 4 AAA’s instead of 2. Contact support if you need help doing that.
	10K Ohm resistor (brown black orange). Prevents the chip from resetting when there is power. The reset pin is active low, which means so long as we have power, it won’t activate and the chip will keep working. If power fails, the chip will automatically reset instead of maybe being in some unstable state.
	22K Ohm resistor (red red orange). The load bias resistor sets the light level at which the LEDs go dim.
	3.6864 MHz crystal oscillator. This provides an accurate clock signal. The ATTiny has an internal clock, but it is not accurate enough for us to keep good time with, so this does the job.
	Two 22pF Crystal stabilizing capacitors.  These may be blue, or orange with ’22’ printed on one side.
	Some kits have a general purpose NPN transistor. This is not in all kits, so don’t worry if your kit does not have one.

Next – Solder it!.