Before we can build Simple Bots, it is important to have a rudimentary understanding of how electricity works (or does not). Electricity comes in two forms, AC (alternating current), which is like the power that comes from a wall socket, and DC (direct current), which is like the power that comes from a battery. In the Simple Bots eBook, all of the electricity for bots will be coming from batteries. So, I will only be explaining DC (direct current) electricity in this Instructable.
When working with DC electricity, there are a few things to keep in mind, but two in particular which you shouldn't forget:
- DC power sources have both a positive ("plus") terminal and a ground terminal.
- In order for any circuit to work, electricity must be able to flow between positive and ground.
In other words, there needs to be something wired between positive and ground that adds resistance to the flow of electricity and uses it up. If positive voltage is connected directly to ground and does not first pass through something that adds resistance, like a motor, this will result in a short circuit. This means that the positive voltage is connected directly to ground.
When positive voltage is connected directly to ground, your battery will get painfully hot and, after a while, may do something bad like leak nasty burning chemicals. It may also result in spontaneous combustion of your circuit.
It is very important to prevent short circuits by making sure that the positive voltage is never wired directly to ground.
Note: A switch does not add resistance to a circuit and simply adding a switch between power and ground will create a short circuit. While building Simple Bots, you should always make sure that your circuit has at least a motor between power and ground.