Bluetooth Deeno-Saur Children's Toothbrush Teardown -- The Electronics Inside 66

A smart toothbrush, that's right, Bluetooth connected, inductive charging, nylon bristled toothbrush. How complicated can it be? Especially since it was not a high end product!

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a531016 over 1 year ago in reply to DAB

Thanks DAB, I'm going to do some probing to see for sure if it is an H Bridge and where it connects to, I'll let everyone know here!
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DAB over 1 year ago

Nice teardown.

An H bridge to drive the coil makes sense, it would be like driving a motor, only this one just drives the vibration.

Same issues of inductive drive and current needed.

I agree, that looks like a very nicely built device for the commercial product.
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a531016 over 1 year ago in reply to astuder

Good find, thank you! Again, I'll bell some out and see what sticks!
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a531016 over 1 year ago in reply to astuder

Interesting idea - I'll put a multimeter on it and see what shakes loose!
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a531016 over 1 year ago in reply to beacon_dave

I didn't know single use vapes were a thing until recently. How many cells are they getting through?
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a531016 over 1 year ago in reply to beacon_dave

And now I wish it played music too!!!
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astuder over 1 year ago in reply to astuder

U4 is probably a LTH7R battery charge controller, pin-out and chip markings match:

lcsc.com/.../Battery-Management-ICs_Shenzhen-Fuman-Elec-LTH7R_C841234.html

The circuit providing 5V to the charger IC is pretty simple: One end of the coil is tied to battery GND, The other end goes through a diode (= half-wave rectifier). The big diode DZ1 (probably a 1N4733, 5.1V zener) limits the max voltage to ~5V. The big resistor marked 2R00 limits the current through the zener if voltage exceeds 5V and/or the battery is fully charged. C12 smooths the 5V. R19 sets the charge current. R18 goes to the microcontroller to monitor charge state, or maybe directly connecting to an LED indicating charge state.
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astuder over 1 year ago

Q1-Q4 are most likely the H-bridge driving the vibration motor. The charging circuit is probably around U4, the 5-pin IC near the battery terminals.
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beacon_dave over 1 year ago in reply to dougw

I was expecting it to play "This is the way we brush our teeth... teeth... teeth..." to a Bluetooth speaker

On a side note, I was surprised to see single use electric toothbrushes on the shelves in the supermarket the other day.
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a531016 over 1 year ago in reply to dougw

Excellent question! And, not a lot. It's eddentially a timer that encourages the user to bursh for a particular time on each part of their teeth. It's your average child oriented app:

https://www.youtube.com/watch?v=XBNt016Jc4k
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