Braun Oral B toothbrush

I just discovered something odd about this electric toothbrush by accident. This is one of thise rechargeable devices that uses an inductive charger with no exposed contacts.

Anyway, I was playing with a portable radio near the toothbrush and I heard a putt-putt-putt sound in the radio when it got near the toothbrush. This is with the toothbrush off, just laying there, not plugged into the charger. Apparently there's a MCU inside the unit that's constantly running, even when it's not doing anything.

While it's not an earth shattering discovery, it got me to wondering what other battery powered devices aren't really "off" when they're turned off, and how does this affect the performance of the battery?
:thinking:

There's amazing low power MCU's these days. They can sleep and use uA's of current and batteries last essentially for their shelf life.

Just think of your quartz or digital wristwatch and how long it lasts off a coin cell.

Yeah, MCUs that draw nanoamps in their quiescent state. I can understand it in a digital clock, but in a toothbrush? What does it have to think about while it's turned off? :duh2: :laughing:

"Yeah, MCUs that draw nanoamps in their quiescent state. I can understand it in a digital clock, but in a toothbrush? What does it have to think about while it's turned off?"

It's thinking about getting turned ON. :laughing:

Any device that has a momentary button to turn it ON and OFF, has some kind of latching circuit running in the background watching for the button push.

dave w said:

"Yeah, MCUs that draw nanoamps in their quiescent state. I can understand it in a digital clock, but in a toothbrush? What does it have to think about while it's turned off?"

It's thinking about getting turned ON. :laughing:

Any device that has a momentary button to turn it ON and OFF, has some kind of latching circuit running in the background watching for the button push.

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Good call, Dave. I just checked them, and while one of them has a physical on/off switch, the other one has a clicky that probably toggles a gate that powers the motor on and off. It still strikes me as funny though!

The two Mexican AA NiCd cell inside are crap and glued into place. Mine lasted just over a year. Never again.

jayflash said:

The two Mexican AA NiCd cell inside are crap and glued into place. Mine lasted just over a year. Never again.

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I've had my Sonicare for about 12 years now, gone through may heads but still the same base!!!

AM and shortwave radio is one of my other hobbies, you'd be amazed how RF-noisy some common household items are. If you want some serious noise, put your AM receiver anywhere within about 20 feet of a dimmer switch..

Another similar erxperiment - put an AM radio near a calculator, tune to an empty spot on the band, then do a square root calculation. You'll hear it "thinking."

jayflash said:

The two Mexican AA NiCd cell inside are crap and glued into place. Mine lasted just over a year. Never again.

Click to expand...

Was the brush you had a Phillips or was it a Braun?

dave w said:

It's thinking about getting turned ON. :laughing:

Any device that has a momentary button to turn it ON and OFF, has some kind of latching circuit running in the background watching for the button push.

Click to expand...

Exactly right, my electric razor does the same thing with my shower radio. I checked just because it had a momentary for an on switch.

was this the Triumph model?