Explaining How Generators Work With Lego! Posted to the 2025 "Make It Spin!" Challenge!

How to make electricity from just Lego parts! If you look up "Lego Generators" on YouTube, you will see these very scary videos about huge machines, and they give no instructions on how they do it! So I'm here to explain how it works, and give a step by step explanation!

Cover Image and DC Generator diagram from https://byjus.com/physics/dc-generator/

I'm just using Lego Technic Small and Large motor, and a couple of gears I had laying around. No real funny stuff.

A gear drive is the basic thing you need to understand. If you want to play around with some of these online, I highly recommend this website!

I'm going to show you how they work with some simple Lego gears and axles, before we get to the big electricity generating stuff.

Sorry for the poor image quality, I'm shooting these with a new camera and it seems to not work as well...

Here I am using a 40 tooth gear attached to a turbine piece, and a 24 tooth gear attached to a beveled 24 tooth gear. If I were to calculate the gear ratio here, its 1 : 1.66666667. That means that for every time the big gear spins, the smaller gear will spin 1.66666667 times. That is not a lot right? Well yes, but imagine how large these numbers can get, 1 : 1.666667 is just 40/28 (40 from the 40-toothed gear, and 24 from the 24-toothed gear)

So what if we have a 100000-toothed gear, against a 8-toothed gear. That's 100000 : 8, or 1 : 12500. NOW THAT IS LARGE!

But what can we do with this? Well, lets move on to our next section!

(Gear Simulator Beta is public use as of 2024.)

Here is where were gonna see how much energy is produced per motor if we rotate it! Using a Arduino motor when doing these experiments, and reaching 100 rpm.

Large motor: 4.0-4.5 Volts

Small motor: 3.5-4 Volts

Now knowing this, lets put this on a graph.

ERROR ON GRAPH: NOT @1000, @100, program would not let me update the X-Axis data after creating

Okay, so lets understand this, normal white LED voltage is 3.2 V, so a single small motor at 100 RPM would cover this. To put into larger perspective, average electric go-kart motors need anywhere from 12-48 Volts! That's about 3-12 large Lego motors.

Well, on average your normal real life generator will produce 12 volts up to larger scales. Here were working small, but in larger scale projects, you need larger scale voltages. Most generators found on YouTube use copper coil wound up tight, and a bunch of strong magnets. As the magnets spin past, the magnetic fields produce a small electrical current in the copper, transferring into some pretty cool high voltages. Our Lego motors don't have that! So go experiment with that, I will be here testing our applications here. BE FREE PEOPLE, HAVE FUN, AND PLEASE SHARE AND LIKE THIS INSTRUCTABLE!