Build Your Coobro Geo
Now that we have our soldering iron warmed up and our clippers close at hand, lets do some soldering. Lets start by soldering up all the components that have short legs, which are harder to hold in place while soldering. The first components we will solder are the resistor networks. Resistor networks are great because they combine a lot of resistors into one nice neat package. We have one network that has nine resistors built in (for the directional LEDs), and one with five built in (for the distance LEDs). The resistor networks in our kit have a very low resistance of only 10 ohms. This is because the forward voltage of the LEDs is very close to the supplied 3.3V. We need to include these resistors to take some control over the current, so we can protect the LEDs and our Atmega328 processor. Learn more on powering LEDs here.
If you have a small vise like the popular Panavise, I would recommend using it to hold the board while soldering the components in. Lets start by placing the two resistor networks in the PCB. The larger resistor will go towards the front of the PCB in the spot labeled RN1, and the smaller will go right above where it says CoobroLabs.com and labeled RN2.
Note: while most resistors do not have polarity, resistor networks do. The side marked with the dot needs to go in the whole marked with the X on the PCB. See the image below.
Because the legs are so short, we are unable to bend them to hold them in place in the PCB. Instead, lets strap them down tight with some Scotch tape.
Now, flip the board over, and lets start soldering in the resistor networks.
When soldering, make sure to heat up both the pin on the resistor and the pad below. Do not use the soldering iron to ‘paint’ solder onto the pad. The solder joint should look smooth and shiny when finished.
The resistors have short enough leads that we don’t need to clip them. That takes care of the first step. Let’s move on to step two.