Author Topic: What type of power supply does a electric toothbrush use to charge?  (Read 1622 times)

I'm sort of thinking about charging a electric toothbrush from 12Vdc and thought a small inverter would do the job.  There are coke can inverters rated at 100w that are overkill as far as capacity goes but are cheapish.  These are quasi-sine wave inverters which the manufacturer says may not work with all devices.  Switched mode PSUs are OK but thyristor control circuits could be an issue.

I'm currently charging a toothbrush through a power meter and it's showing around 3.6-4VA, 0.6W.  There's obviously some switching going on as the readings are variable.

Can anyone suggest an alternative way of achieving this?

Ta

Kim

  • Timelord
Re: What type of power supply does a electric toothbrush use to charge?
« Reply #1 on: 10 December, 2021, 07:34:07 pm »
They tend to charge by induction through the base of the toothbrush.  No idea if this is just mains fed to a coil in the base, or if there's high-frequency switching going on.

Someone must molish a USB-powered toothbrush, Shirley?  That way you could side-step the mains inverter entirely.

Re: What type of power supply does a electric toothbrush use to charge?
« Reply #2 on: 10 December, 2021, 07:48:46 pm »
Wrapped an O’sillyscope probe around the base of my Oral B and it’s a 32 KHz sine wave.

fruitcake

  • some kind of fruitcake
Re: What type of power supply does a electric toothbrush use to charge?
« Reply #3 on: 10 December, 2021, 08:02:39 pm »
I have a suggestion for a workaround. For use when travelling, I bought an Oral-B electric toothbrush that runs on a pair of AA batteries. It works just fine. It takes standard Oral-B toothbrush heads. Battery life is quoted in months.

hellymedic

  • Just do it!
Re: What type of power supply does a electric toothbrush use to charge?
« Reply #4 on: 10 December, 2021, 08:27:12 pm »
I also have a 2AA Oral B toothbrush for travelling.
Batteries last AGES.

I think a full mains charge on an Oral B brush gives 14 x 2 minute brushing sessions, so you can take a fully charged brush for a short trip without a charger.

Re: What type of power supply does a electric toothbrush use to charge?
« Reply #5 on: 10 December, 2021, 08:52:07 pm »
There has to be clever stuff going on in the charging base, and that is confirmed by 32 kHz oscilloscope readings.

At the minimal power of less than 1 W, it's likely that the input is simply full-wave rectified before other creates the 32 kHz. Any device with a full-wave rectifier at the start will run from any inverter without problems. 
Quote from: Kim
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Mrs Pingu

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Re: What type of power supply does a electric toothbrush use to charge?
« Reply #6 on: 10 December, 2021, 10:26:39 pm »
I also have a 2AA Oral B toothbrush for travelling.
Batteries last AGES.

As in more than 2 weeks?
My mains one barely lasts a week these days.
Do not clench. It only makes it worse.

Re: What type of power supply does a electric toothbrush use to charge?
« Reply #7 on: 10 December, 2021, 10:49:35 pm »
Mains ones usually contain a single Nimh AA, which contains at best half as many voles an Alkaline one.

hellymedic

  • Just do it!
Re: What type of power supply does a electric toothbrush use to charge?
« Reply #8 on: 10 December, 2021, 11:09:31 pm »
I also have a 2AA Oral B toothbrush for travelling.
Batteries last AGES.

As in more than 2 weeks?
My mains one barely lasts a week these days.

My travel toothbrush is only used when I stay away from home overnight. I've not stayed away much over the last 2 years due to the pandemic. I've not replaced the batteries for around 4 years but I really don't know how many hotel nights this represents!

fruitcake

  • some kind of fruitcake
Re: What type of power supply does a electric toothbrush use to charge?
« Reply #9 on: 11 December, 2021, 12:27:38 am »
So far my AA electric toothbrush has lasted at least 60 toothbrushings on a standard pair of Duracells.

The benefit for travelling though is that you can simply change the battery for another pair of Duracells if it runs out. So instead of carrying a mains charger and its plug with you, you need only carry these batteries.

Re: What type of power supply does a electric toothbrush use to charge?
« Reply #10 on: 11 December, 2021, 10:51:19 am »
AA battery brush sounds as if it's an option.

14x2 minute sessions is fine except we both use the same body so that's only 3 days, less as the battery is no longer working to full capacity.

Thanks all.

Zipperhead

  • The cyclist formerly known as Big Helga
Re: What type of power supply does a electric toothbrush use to charge?
« Reply #11 on: 12 December, 2021, 06:15:28 pm »
They tend to charge by induction through the base of the toothbrush.  No idea if this is just mains fed to a coil in the base, or if there's high-frequency switching going on.

Someone must molish a USB-powered toothbrush, Shirley?  That way you could side-step the mains inverter entirely.

I bought a USB powered charging base for my toothbrush. It lives in the bag of usb charging stuff for travelling.
Won't somebody think of the hamsters!

Mr Larrington

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Re: What type of power supply does a electric toothbrush use to charge?
« Reply #12 on: 12 December, 2021, 07:02:37 pm »
I'm old-skool and thus use an analogue toothbrush for travelling ;D
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CommuteTooFar

  • Inadequate Randonneur
Re: What type of power supply does a electric toothbrush use to charge?
« Reply #13 on: 12 December, 2021, 10:49:18 pm »
I am curious are electric toothbrushes good anyway?  I was a fast vigorous hand brush user.  After a suggestion from the hygienist, concerned about the rear teeth, I switched to a Philips Sonicare electric toothbrush. The numbers my dentist was reading out for gum condition started to rise. I switched back to the hand brush and  the numbers started to fall again.  Now I mostly use the hand brush and occasionally use the small headed electric to make sure I can get at the low rear teeth.

FifeingEejit

  • Not Small
Re: What type of power supply does a electric toothbrush use to charge?
« Reply #14 on: 12 December, 2021, 11:26:59 pm »
I also have a 2AA Oral B toothbrush for travelling.
Batteries last AGES.

I think a full mains charge on an Oral B brush gives 14 x 2 minute brushing sessions, so you can take a fully charged brush for a short trip without a charger.

I'm well beyond that from my most recent charge, can't remember if it's 2000mAh or 2500 mAh nimh rechargeables  that are in though.
I also have a USB AA charger at work that I could bring home if I wanted to travel with that instead of a manual brush.

I suspect the success of an electric over a good manual brusher is in how you use it, I always got good numbers whne using a manual brush because I basically destroy a brush every other month.
Whether I'm any better with the electric I dunnoh as the tooth that was already sliced diagonally and sieve like in its casing keeps turning out to have failed. (see trivial health matters post with my various trips to dentist through the last 3 months mentioned)

T42

  • Patron saint of the dry joint
Re: What type of power supply does a electric toothbrush use to charge?
« Reply #15 on: 13 December, 2021, 07:27:46 am »
Back in Norn Iron we had steam-driven reciprocating toothbrushes. You just had to be careful where you pointed the exhaust, but otherwise they did a good job, and heated the bathroom into the bargain. Only time they failed was when the cellar-wight was sulking or had slept in, and didn't get the turf into the furnaces early enough to give us a good head of steam.

Of course, when the Hall was really cold in winter the steam would condense in the pipe, so that instead of a pleasant, invigorating experience you would get a splatter of boiling spray up your arm.  Happy days!
I've dusted off all those old bottles and set them up straight

Re: What type of power supply does a electric toothbrush use to charge?
« Reply #16 on: 13 December, 2021, 09:49:36 pm »
Steampunk oral hygiene.
And Darkness and Decay and the Coronavirus held illimitable dominion over all.

Re: What type of power supply does a electric toothbrush use to charge?
« Reply #17 on: 17 December, 2021, 12:41:08 pm »
They tend to charge by induction through the base of the toothbrush.  No idea if this is just mains fed to a coil in the base, or if there's high-frequency switching going on.

Someone must molish a USB-powered toothbrush, Shirley?  That way you could side-step the mains inverter entirely.

I bought a USB powered charging base for my toothbrush. It lives in the bag of usb charging stuff for travelling.

Ah, one of these perhaps:
https://www.amazon.co.uk/Electric-Toothbrush-Toothbrushes-Universal-Connection/dp/B07FH7M2P1

But why not from a car charger port?  5v 500mA requirement.


Re: What type of power supply does a electric toothbrush use to charge?
« Reply #18 on: 17 December, 2021, 01:35:45 pm »
This guy's been running his toothbrush off an Apple charger https://youtu.be/kQ4m0dM7pVE?t=551
(Doesn't sound like an optimum solution!)

Mine runs on 2xAA (eneloops, usually) and lasts months and months and months.

Re: What type of power supply does a electric toothbrush use to charge?
« Reply #19 on: 17 December, 2021, 02:47:02 pm »
Old school toothbrushes rule 😂

Zipperhead

  • The cyclist formerly known as Big Helga
Re: What type of power supply does a electric toothbrush use to charge?
« Reply #20 on: 17 December, 2021, 03:08:27 pm »
They tend to charge by induction through the base of the toothbrush.  No idea if this is just mains fed to a coil in the base, or if there's high-frequency switching going on.

Someone must molish a USB-powered toothbrush, Shirley?  That way you could side-step the mains inverter entirely.

I bought a USB powered charging base for my toothbrush. It lives in the bag of usb charging stuff for travelling.

Ah, one of these perhaps:
https://www.amazon.co.uk/Electric-Toothbrush-Toothbrushes-Universal-Connection/dp/B07FH7M2P1

But why not from a car charger port?  5v 500mA requirement.



That's the jobby. As to why not in the car - I don't have a car so I can't answer that. I'm sure if I tried it on my motorbike it would just slide off the tank.
Won't somebody think of the hamsters!

Kim

  • Timelord
Re: What type of power supply does a electric toothbrush use to charge?
« Reply #21 on: 17 December, 2021, 03:53:24 pm »
They tend to charge by induction through the base of the toothbrush.  No idea if this is just mains fed to a coil in the base, or if there's high-frequency switching going on.

Someone must molish a USB-powered toothbrush, Shirley?  That way you could side-step the mains inverter entirely.

I bought a USB powered charging base for my toothbrush. It lives in the bag of usb charging stuff for travelling.

Ah, one of these perhaps:
https://www.amazon.co.uk/Electric-Toothbrush-Toothbrushes-Universal-Connection/dp/B07FH7M2P1

But why not from a car charger port?  5v 500mA requirement.



Because if you have a car the baby elephant could brush your teeth for you?

I assume lack of imagination on the part of the marketroids, who've never been camping.

Re: What type of power supply does a electric toothbrush use to charge?
« Reply #22 on: 17 December, 2021, 04:31:44 pm »
This guy's been running his toothbrush off an Apple charger https://youtu.be/kQ4m0dM7pVE?t=551
(Doesn't sound like an optimum solution!)

Rewound a bit from your link and his toothbrush is Qi compatible, which the Apple charger also is.

Re: What type of power supply does a electric toothbrush use to charge?
« Reply #23 on: 17 December, 2021, 04:42:41 pm »
I'm very disappointed that nobody has suggested converting the toothbrush to clockwork.
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Mike J

  • Guinea Pig Person
Re: What type of power supply does a electric toothbrush use to charge?
« Reply #24 on: 17 December, 2021, 06:16:04 pm »
Bicycle powered toothbrush like in Red Dwarf (although that was a hairdryer I think)?