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I thought I'd take one of these apart, thinking the circuitry was going to be very minimalist.  I thought it might be a chip, transistor and protection diode, but it really goes to town on noise suppression and overload protection.

https://youtu.be/qTeZVqoVe7U

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Inside a Bumble Ball - with schematic

The circuitry in this toy was more sophisticated than I was expecting. Mainly for safety and electrical interference reasons. These were apparently first marketed as a dog toy, then evolved to become a kids toy too. The construction is mechanically quite complex to allow activation of a free spinning assembly inside the ball. The circuitry has lots of protection for overcurrent if the motor stalls, and its notable that as the current increases the voltage at the source (negative) connection of the MOSFET will rise, potentially acting as current regulation. If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:- https://www.bigclive.com/coffee.htm This also keeps the channel independent of YouTube's algorithm quirks, allowing it to be a bit more dangerous and naughty. #ElectronicsCreators

Comments

Mike Page

The 0R68 in the source provides a bit of current feedback at startup by eating into Vgs, but at the expense of running the FET less like a switch and more like a dimmer. That's why it needed extra heatsinking. I can less understand the PTC in series though. It's something you want to trip decisively. I don't know how it would behave in this kind of scenario, and it's not easy to model because of the thermal aspect.

Jonathan Hughes

it looks like a over sized Everlasting Gobstopper from Willy Wonka. LOL