This instructable will show you how to build one of the ENTS rocket badges. The badges are powered by an Attiny85 and will blink 10 bi colour LEDs in various patterns when finished.
Step 1: Assemble Materials
A list of the components you'll need to build the rocket badge is below. While you're gathering your supplies, you should let your soldering iron heat up.
1 x Programmed Rocket Board (See photo for notes)
1 x 0.1uF Capacitor
5 x 56 Ohm Resistors (Colour stripes are: Green Blue Black Gold)
10 x Bi-coloured LEDs
1 x Tactile Button
2 x Battery Holders
2 x CR2032s (not pictured)
4 x Bits of Kapton tape
See the attached photos for help identifying components.
Step 2: Solder the Battery Pad
Now that your iron is hot and you have all your components ready, we can just right into soldering.
The first step is to put a bit of solder on the battery pad. You don't need much; just enough solder to raise the pad above the blue solder mask.
First put your board into a "helping hand" or other clamp, it'll be a lot easier to solder if your board isn't sliding around the table. Then melt a bit of solder onto the tip of your iron. This is called wetting the tip and will help heat transfer from the iron to the pad. Without using any pressure, rest the tip of your iron on the pad and hold it there for a few seconds to let it heat up. Then add a bit of folder to where the iron touches the pad and it should immediately melt.
Take your time and get a feel for how the solder melts and flows onto the pad. Also, be sure to do this step for the battery pad on the front and back!
Step 3: Battery Clip, Button, Capacitor and Resistors
You can insert everything except the LEDs now. It doesn't matter which way the resistors or capacitors go in; they don't have a positive or negative side. The battery clip can go in either direction as well, but it'll look nicer if you place it so that it matches the white silkscreen. The button only fits in one direction, so you don't have to worry about putting it in the wrong way.
Once everything is placed, cover it with masking tape so that it doesn't fall out when you flip it over in the next step. The button doesn't need to be taped, it'll hold itself in.
Step 4: More Soldering!
Now you can flip the board over and start soldering in the components.
Clean the iron tip off with a wet sponge or brass wool, which should be near the soldering station. Now wet the tip with solder as you did before soldering the battery pad. Hold the iron so it touches the pad and the component lead and count two seconds. While holding the iron in place, add a bit of solder to where the component lead and the pad on the board meet. You don't want a big blob of solder, but a small conical shape. If you have too much on a joint, try cleaning the tip and dragging some of the solder to the top of the lead.
Now clean the tip of the iron and solder the rest of the joints.
Once everything is soldered, you can cut all the leads flush with the board, except for the button and the battery clip. Their leads are small and won't bother anything.
Insert the other battery clip and solder it when you flip the board back over.
Step 5: Insert the LEDs
Before inserting any of the LEDs, take a look at the bottom of one and notice the flat side in the base of the plastic. In a two lead LED, the flat side will always be the negative side. Now look at the board and notice that there is a flat side and dot on one side of the LED silkscreens. Make sure that you insert the LEDs so that the two flat spots line up.
Instead of taping the LEDs, try to "semi-clinch" the leads. When you put an LED in, bend the two outer leads so that they're at about 45 degrees. That will stop them from falling out when you solder them in place. You might find it easier to clinch the leads by keeping the board upside down when you insert the LEDs.
Step 6: Solder the LEDs
Solder the LEDs and trim the leads with flush cutters, exactly as you did with all of the other components.
Step 7: Apply the Kapton Tape
If you look at the battery holder, you'll see that the leads of one are right in front of the other. Electrically, that lead is the positive side of the battery. You want to avoid letting the negative (bottom) side of a battery from touching it, so we'll just cover it up with a bit of Kapton tape.
Be sure to do this on both sides of the board.
Step 8: Insert the Batteries and Test
If it isn't working properly, take the batteries out and look to see if there is a solder blob connecting two leads that shouldn't be touching or a solder joint that doesn't have enough solder to make a good connection.