[Sam Ben-Yaakov] has another lecture online that dives deep into the physics of electronic processes. This time, the subject is magnetic transformers. You probably know that the ratio of current in the primary and secondary is the same (ideally) as the ratio of the turns in each winding. But do you know why? You will after watching the video.

Actually, you will after watching the first two minutes of the video. If you make it to the 44-minute mark, you’ll learn more about Faraday’s law, conservation of energy, and Lenz’s law.

One of our favorite things about the Internet is that you can find great lectures like these online, both from university programs and from individuals like [Dr. Ben-Yaakov]. There was a time when you would have had to enroll in a college to get the kind of education you can just browse through now.

Too much math and technical detail for you? We get it. You don’t need to understand all of this to use a transformer. But if you want to understand the math and the physics behind the things we do, nothing is stopping you. Even if you need to brush up on math, there are plenty of similar lectures to learn about that online, too.

Want a university class that is more practical? We hear you. Prefer simulation to math or solder? We hear you, too.

Earlier in 2025 we celebrated Prime Day—the yearly veneration of the greatest Transformer of all, Optimus Prime (in fact, Optimus Prime is so revered that we often celebrate Prime Day twice!). But in the fall, as the evenings lengthen and the air turns chill, we pause to remember a much more somber occasion: Black Friday, the day Optimus Prime was cruelly cut down by the treacherous hand of his arch-nemesis Megatron while bravely defending Autobot City from attack. Though Optimus Prime did not survive the brutal fight, the Autobot leader’s indomitable spirit nonetheless carried the day and by his decisive actions the Decepticons were routed, fleeing from the city like the cowardly robots they truly are and giving over victory to the forces of light.

Although Optimus Prime’s death was tragic and unexpected, things are often darkest just before dawn—and so, even though today is called “Black Friday” to remind us of the day’s solemnity, we choose to honor him the way we honor other important historical figures who also laid their lives upon the altar of freedom: we take the day off to go shopping!

Below you’ll find a curated list of the best Black Friday deals that we’ve been able to find. Stand strong in the shadow cast by that long-gone noble Autobot, for by his sacrifice the day was won. Now, as Optimus would say, transform, my friends—transform and buy things.

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