Thursday, August 21, 2008

Bubba Toothbrush

Instead of a long crazy "hey you kids get off my lawn" rant, today's topic is oral hygiene.

I am on my 2nd Sonicare toothbrush. They last about 5 years in my experience, then they go poof. In reality there really isn't anything wrong with them other than they have NiCad batteries and the batteries just get worn out (or get a memory of zero).

I opened my first one (about 5 years ago) by splitting the case down the seam. This is obviously how they are put together... and they obviously think that is how you are going to take them apart. Smart thinking. Its really easy to tear them up this way. And then there is a really fragile circuit board with about 6-8 solder points that all have to be unsoldered to get to the batteries. And the batteries are super epoxified to the back case. All in all, not an easy project.

So when this one died the long slow painful death, the cheap ass bastard kicks in. My last one was about $100.... which isn't bad if you think of it as $20 a year. But those manual toothbrushes are cheaper than that.

This time I googled around looking for options. Everyone bitched about how hard it was to get the circuit board off in one piece or without burning it up, yadda yadda. Then I find this guy that talks about just cutting a hole around the battery box with a Dremel. Now I actually have one of these, but it is my firm belief that this is the ultimate "girl's tool." In other words, it works great on balsa wood. (80,000 rpm and 0 torque.)

So lets begin, shall we?


The cuts, made with a hacksaw in about 2 minutes. It would take me that long to find my Dremel. And then I'd have to replace that little cutting wheel at least 8 times when it explodes during a cut. Yeah, go with a hacksaw.



And this already looks easier. I nailed it when it comes to hitting the "battery box."





Batteries out... and a nice replaceable cover.



And here I have taken some off the shelf NiMh batteries and soldered them in. I make that sound short and simple, but for me it took a while. I am not some electrical whiz, just a guy with a soldering iron. I extended the original + and - poles to make longer pigtails. I had a little bit of a difficult time with one tying to one of the negative poles. The negative side of the battery makes a damn fine heat sink.




And here it sits in the charger... charge light blazing. (Okay, Blazing might be an overstatement.)













Add a little electrical tape and viola (or cello, or whatever). By the way, the little battery bastards are a bitch to get back in. The originals had finer wire on the upper side and a thin metal strap on the lower side (which I replaced with wire). Tight fit. Push. Shove. Swear. Accidentally rip one solder off of it. Repeat.

18 comments:

Kari said...

Why, I believe you saved us enough money to buy a tortilla press and a warmer!

Spork In the Eye said...

or food.

Kari said...

But think about all the nice, warm, fresh tortillas you could have...

Og Make Blog said...

Uhhhhh....... no....don't... stop!

Replacing NiCads with NiMH is not a good idea. I will leave out the details, but unless you modify the charging circuit, you are likely to have either a very short life or a very uncharged NiMH battery (depends upon the charge rate of the original.)

Spork In the Eye said...

see:
http://www.greenbatteries.com/bachfa.html#NiCD%20charger%20for%20NiMH%20batteries

my type would be #2. Trickle charge. Long time.

Seeing as I use it 2 minutes at a time, then have the possibility of charging it 4-12 hours between times, I'm okay with it.

It's easy to replace them now, so if my $4 goes south, I can spend another $4 and put newer NiCads back in.

Spork In the Eye said...

oh, and by the way og:
take off, eh?

Og Make Blog said...

What's that, eh? Oooh, takeoff, ya, you betcha!

Was that a 2.8V NiCad you replaced, or was it one large 1.4V?

Spork In the Eye said...

standard 1.2v AA x2

Og Make Blog said...

Yes, but what size NiCad did you replace? It looks like an F or C type cell... and 1.34 Volts.

Spork In the Eye said...

same answer as the first time: standard 1.2v AA x2

Spork In the Eye said...

Maybe I should be more specific here. When I googled around for options, 1.2v NiMh batteries were a known option. The charger fully charges them, albeit slowly. However since the damn thing only runs 2 minutes at a time and holds the charge 3 times as long, it is not seen to be an issue. It's also rumored to make a fine lock pick, though I can not confirm that one.

Og Make Blog said...

Now I see it... just a bad perspective, as the NiCads look so much larger in that picture. I would investigate the lock picking abilities further ... but then again, I knew a fellow that could unlock a dead bolt with a plastic coffee stirrer (straw.)

Spork In the Eye said...

followup: 8 hour charge yields 1 week normal use. Since I dont think that's fully charged, I'd bet you could get 2-3 weeks out of it. Definitely better than before (not working at all).

Lee said...

Do you have a way for replacing the NiCad's with an ac/dc adaptor? Can you do the work for me? I have three kids and not the time to do it myself.

Spork In the Eye said...

Ac adapter? Not a clue. I suspect they left that off to avoid liability on electrocuting folks.

I don't mind breaking my own stuff, but I wouldn't even try to break someone else's. And while I suspect you could do this with an appropriate DC transformer... I am no electrical genius.

If I wanted to try, I'd look for something with about a 2.4 volt output (AND A GFCI!!) and would just go to town.

Og Make Blog said...

To make a suitable DC adapter is easy and several ways to do so, but perhaps the easiest and most safely packaged version is to find a wall wart supply rated at 5V. Find a matching female connector and bypass the batteries with a 3 V regulator. Use an LM317 with the appropriate resistors to regulate down from 5V to anywhere from 2.5 to 3.0 V(I could dig up the values if needed.)

El Gee said...

What?? No USB powered tooth scrubber?

Spork In the Eye said...

There you go Lee -- Marry El Gee's comments with Og's comments and you have the perfect hardwired toothbrush. Add a laptop to the mix and you even have a portable wired toothbrush.

...now try explaining to your IT department why you dropped the laptop in the sink.