Big roller coaster type signal called AC> small roller coaster> signal that looks like a bunny hopping> bunny starts flying.
Other than turning into giant robots, transformers can increase or decrease voltage too. Here, we are going to use a “step down” transformer, because we want to step down the voltage. A transformer is basically 2 windings, “primary” is connected to the supply, “secondary” is the output. Think of it’s working like a grown Mario touching a villain and becoming small (don’t overthink this analogy). That’s what happens to voltage when it goes from primary to secondary, it becomes small (its amount depending on the winding). Signal is still AC.
The signal is still continuously changing between positive and negative. We don’t want that. This is where the “bridge rectifier” comes in. The diodes here are arranged in such a way that even the negative half of the signal are now positive. Signal here looks like positive signals connected one after the other. We call this “pulsating DC”.
Think of diodes like a Mario’s stage screen, signal can only go forward, not backwards (don’t overthink this analogy either).
Voltage regulator and filter:
We now need to make this signal flow without variation and have a constant voltage. Let me introduce you to “LM78xx”. The “xx” here can be “05”, “08”, “12” etc. This means LM7805 will give the output of 5V, 7808 will give 8V, you get the gist. LM78xx has an evil twin, “LM79xx”; whose output is same as LM78xx, but negative. But we are not using that here.
We now have DC signal with a usable voltage. But we also have ripples. These are little AC brats that managed to sneak through. We’ll let Colonel Capacitor (C1 & C2 in the diagram) take care of them. When pulsating DC reaches its peak value, capacitor holds that. When the value decreases, capacitor’s value SLIGHTLY decreases until the next peak value. The final signal kind of looks like a dirt bike terrain. Now we have the DC signal we all like and adore.
Its not a perfect waveform, but with better filter circuits, we can get close.