Electronics Inside a Philips Sonicare Electric toothbrush

Today a coworker of mine gave me his old Philips Sonicare toothbrush. He said it had stopped charging and would no longer work. That was a good opportunity for a tear down ūüėČ

Lets see what makes this baby chooch….(As the great man himself said https://www.youtube.com/watch?v=lA0kiYqyBmo)


There’s very little to this device. it seems like there’s just a micro controller running the show, like every other product. (there’s more horsepower in a toothbrush these days than an a 50 year old Supercomputer!) it probably does the following tasks( my guesstimate)

  1. Running the motors
  2. Reading user input via the two push buttons (I accidentally De-soldered one Push button, while trying to De-solder the battery)
  3. Battery charging and discharging
  4. LEDs and Blinkenlights (Coz humans love ’em )



Quick hardware analysis

A quick analysis of the PCB shows a micro controller(PIC16F726 to be precise) . Q1 seems to be a dual P channel MOSFET ( marked as ISC 6981D ). Q2 is marked AO8808A a dual N Channel MOSFET. The MOSFETs formed an H bridge which drives the “Ultrasonic motor” which I plan to get to run soon. then there’s a few sundry(read boring/uninteresting) components which probably are there for over voltage protection, an LDO, Li-Ion battery charger Etc. (High Res Image of the PCB ).

Then there seems to be 6 test Points which are conveniently labelled for easy debugging( or hacking I guess!) I’ll probe those and see what they do probably try out a few common baud rates and see what the Micro spits out. There are plenty of test points on the PCB that should include the programming pins for the micro as well.

That’s pretty much it for the electronics side of things.

Then there are other things like the Motor, A AA size Li-Ion battery, a charging coil. The coil probably forms an air core transformer with the charging dock, but I;m still not clear on how it is rectified back in to DC for charging the battery, with so few components and no bulky capacitors on the PCB.

I’ll probably power up the micro controller and see whats being sent out over the UART. Next on my To-do list would be to get the motor running and after that i would like to check out how the charging subsystem works with the weird air core coil arrangement. The weekend is fast approaching, so this guy should keep me busy for a good part of the weekend.


Special Thanks to Alex for donation :)


Murli’s blog has a new home

Last weekend over thanksgiving, I finally found some time to move over my blog to a custom hosted solution over from the old one. I now have a custom WordPress install(this might change soon, as¬†I’m looking at other options, which are more efficient like jekyll¬†). ¬†The blog should now be snappier, also i’m planning to add a few bells and whistles on the backend (git server, host some files etc). On the hardware front, I¬†am currently working on the ESP8266¬†on adding an Epaper display and a few custom sensors. I’m using a rather interesting and firmware framework called SMING, which is an interesting hybrid between the Arduino framework and native GCC. Sming I feel is still rather nascent, but the developers are working hard on refining it.¬†I plan to finish the e paper display interface this week, and then¬†I can go ahead with finishing the project,¬†something that looks more like a product than a quick¬†hack. I’ve had a few stumbling blocks along the way, which i have put them aside for now.

Its been a long time dream of mine to build some thing that look more like a store-bought product than something hacked together. This is proving to be a much tougher and more¬†resource intensive than I expected, but I’m being persistent and have been working on and off¬†on it for a while now. Hopefully I will have something cool to show off soon, and will be richer with interesting¬†experiences on developing a product from scratch.¬†

Also¬†my Rpi Zero came in this weekend.¬†I played around with it a bit, I’m¬†waiting on some cables to come so I can have a stable setup, the cables from my previous Rpi hack are kinda dodgy and dont seem to work very well,¬†I will¬†post a detailed review on the Zero soon.

Raspberry Pi laptop

Recently, I got a used Atrix 4g lapdock for 30 bucks off of craigslist. It was a really good deal for a device that packs a USB hub, a 10+ inch LCD a keyboard, a trackpad and also a 10000mAh battery. Supply it with a processor and it can be a full fledged laptop computer. My atrix 2 worked fine with the lapdock. I used it a lot for watching youtube videos and for PDFs.

The good thing about the lapdock is that it has everything that is needed to setup a raspberry pi. I had one of the earliest revisions of the raspberry pi which up until now I used as my media file server. And the only was i would interact with it was over SSH since i really hated the mess of wires that would come with setting up the monitor and keyboard for the Pi. The lapdock was a very elegant solution to this problem. it was just a matter of splicing some wires together and some soldering before i would get my very own Rpi Laptop. Here’s the finished product.


If you are looking to make one below are some resources.

Here’s the instructional video from Adafruit that i referred to make this project. do check it out.

Here’s another blogpost which i think managed to do away with the soldering altogether but you might end up spending some extra money. but is more rugged and sturdy than the home-made cable solution.¬†http://rpidock.blogspot.com/2012/05/raspberry-pi-and-motorola-lapdock.html

Here are the cables and stuff that you will need for this project.

1.      Micro USB B Male Female M/F Extension Charging Cable

2.     HDMI 1.4 D type Micro HDMI Male to Micro HDMI Female M/F

3.     HDMI Male to Micro HDMI Female Adapter/Converter

4.     Micro USB cable

You will also need Soldering iron and some heat shrink tubing for the project. So keep that handy.

Do let me know how it goes.

Questions?? Fell free to post them in the comments below!


Teardown of a 13 year old canon digital camera.


canon camera teardown, a set on Flickr.

A couple weeks ago, at work I found a digital camera that was thrown away in the recycle bin, it had a broken LCD and everything else seems to be in good shape. It was a 2.1 Megapixel Shooter so i figured it must really old. On googling I found that it was launched in 2001 and one of the smallest digital cameras of its time. and cost like $600 US! these days you can get a decent DSLR for that price. Check out the review of this device here!

Enough chit-chat, lets get to the real deal. I wanted to take the sucker apart and see the innards and understand its working. The camera is enclosed in a metal enclosure and could easily take a drop or two without taking much damage. Dissaembly was easy as the entire case was held together by philips head screws. The canon engineers were able to cram in a lot of stuff into a relatively tiny case,about the size of a pack of cards. It even had its own Li-Ion battery with a seperate external charger.

I have posted the photos of the teardown on my Flickr account. The pictures have elaborate descriptions feel free to browse through them. Feel free to ask any questions in the comments below! Enjoy!

Restoring the Windows Boot Partition…..

I have a Dual Boot boot system Running Ubuntu 12.04(LTS) and Windows & Home Premium(x64).

The other day i was booted into ubuntu and had to use gparted to partition and format a flash drive to use with my Pogoplug-B01. And i by-mistake formatted the windows boot partition . Oops. I restarted my system and could not  boot into windows! For me Windows is like a necessary Evil . Its where all my games reside! All for the other programming related stuff i use ubuntu. So i needed to get the windows partition up and running.

Also before you go ahead i would recommend you take a backup just in case anything goes wrong by booting into the system by a ubuntu live CD.

This can only be used to repair a system where the boot partition is either formatted or is corrupted. This would not work if the main system partition containing the OS itself is damaged.

Starting Windows Vista Microsoft made the boot partition a separate partition (generally 100MB)from the partition containing the actual OS files.

Step 1 Get the appropriate WIN 7 recovery Image from here.

Step 2 Create the CD/DVD or the USB stick(Skip to Method 2 in this Link )

Step 3 Without the boot sector When you turn on your computer u will get a ‘no Operating system Found’ error . So you will need to set your boot drive to the DVD or the USB drive Depending upon whta media you are using.

Step 4 Once you Boot into the Repair Disk Hit Startup Repair. If that fixes the issue. you are all set! But for me that was not so Easy. I Selected the Command Prompt Option the type in the following commands and hit enter after each command


list disk

select disk (followed by the number of the OS disk; most likely 0)

list partition

select partition (followed by the number of the Boot partition; most likely the 100-200Mb partition)



Step 5 Now again type


list disk

select disk(followed by the number of the OS disk; most likely 0)

list partition

make Sure there’s a star(*) against the selected boot partition

then type format and hit enter. This will format the boot partition to NTFS.

Step 6 Now to repair the boot partition make the boot partition active by repeating the STEP 4

next enter following commands and hit enter after each command.

bootrec /fixmbr

bootrec /fixboot

bootrec /rebuildbcd

Step 7 Now restart the computer with the recovery media plugged in.

now in the recovery options select the ‘Startup Repair’ option. It should b able to fix any other issue with the boot sector and restore it to the optimal state.

Now Restart the computer and this time remember to unplug the media when the system shuts down.

Have Fun.

Let me know how i goes in the comments below! :)

Best of Luck!

These Posts Were really helpful:

[1] http://www.windowsreinstall.com/winre/createfromiso/#.Uhm2oG3tx24

[2] http://www.selectrealsecurity.com/fix-windows-startup

[3] http://windows.microsoft.com/en-US/windows-vista/What-are-system-partitions-and-boot-partitions

[4] http://windows.microsoft.com/en-us/windows7/create-a-system-repair-disc

select partition (followed by the number of the OS partition; most likely the largest partition)

Playing with the UART on the TI Stellaris Launchpad.

I just started playing around with the TI Stellaris Launchpad a couple of days ago.

The Launchpad is a pretty powerful little dev board. It has¬† ARM Cortex-M4F core at it heart. The really awesome thing is that there’s a Full fledged¬† debugger built-in which makes it a really good board to start with ARM micros.

I was fiddling with the UART trying to setup two way communication with the micro. so i started out with the uart_echo project included in the Stellarisware bundle.

The uart_echo code works with the UART0 of the micro and i wanted to get it running on the UART1, Sound simple right? But for a Newbie to this micro-controller it might be a bit difficult. That was what happened it took some amount of digging around the internets and the documentation to get the code to do what i wanted but finally it started working

Here’s what i ended up doing. First i reconfigured all the I/Os the UART1 Pins can be used either on PB0,1 or on PC4.5. I used the PB0 and PB1 pins. changed the code in all the other relevant places in the main code, tried running the code . I got the “Enter Text” messgae on the terminal. It means the Tx was working fine. but i could get a echo back from the micro. The uart_echo uses the uart receive interrupt which was not being triggered. So i needed to get the interrupt triggered when the data comes in on the RX pin. by the way i did try the echo function running in the while loop and that confirmed that the physical connection was good and that the code was working.

I stumbled upon a forum post by another person facing similiar problems where he suggested that i make changes to the interrupt vector table in the startup_ccs.c file¬† i simply replaced the IntDefaultHandler with the UART1IntHandler which is the interrupt handler for UART1 and like magic the code started working! Here’s the final Ti Code Composer studio v5.2 project. You can Import the code directly into CCS using the import option.

Planning to get the PWM working now…..will post on it soon…

Philips SHH7810 In-ear headset for Mobile Phone review

A couple of days ago i received in my order of Philips SHH7810 in-ear headset from Flipkart.com. They delivered it in like 2 days as promised. I love their service and sometimes the price is also very reasonable as compare to brick-and-mortar stores,which was true in this case.I got it for 985 INR,which i think was pretty reasonable.

The SHH7810 in my opinion is one of the cheapest and quality headsets with inline microphone that money can buy,I had done some research prior to finalizing this one, i coudn’t find any decent brand(aka sennheiser,skullcandy,sony,etc) earphones with inline mic and call.answer button,there was one from skullcandy around the 1k INR range but i was using the skullcandy ink’d for the past 8 months which was very similiar,I wanted some change and this had to be it.


It arrived in a nice little flipkart bubble wrap lined mailer bag.The contents inside were nicely protected and did not show any signs of stress from the shipping .

I sometimes hate the amount of packaging that comes with the earphones,there’s too much plastic and takes a lot of effort to open it up. :(

The contents of the package include the standard fare 3 different sizes silicone ear plugs. And an interesting compatibility adapter that allows the headset to work with almost all of the commonly available phones with 3.5mm standard connector

I had a Motorola so i did not need the adapter!

Plugged it into my atrix 2 ,there were no issues ,the headset was recognized . Tried playing some tunes and sounded good and was stereo made some calls.I was able to pick up calls with the call/end button,Mic also worked good.

the thing that i hate about this headset is the inline volume control! I was fooled by the images on flipkart and other places! I had thought it was a push button based solution,similiar to the ones found in the inbox headsets that come with phones.Sigh! it was just a crappy volume slider which instead of sending a command to the phone to change the system volume of the phone just fiddles with the signal by changing the inline resistance which is a BAD way to do it. And from past experience is one very big potential point of failure! .In headphones these things are the first to fail. I hope that Philips has designed it well enough ,and it lasts atleast 6 months without failure!. If the headset lasts 6 months of rough use (or rather abuse!) i would call it well worth the money!

Moving on to the sound quality of these phones,the overall sound quality is good for the price. The bass i feel sometimes is as good as Sennheisers and the Skullcandys from a higher price range.Sometimes though i feel the bass is too much and it overpowers the mids ,and the mids get supressed.The Highs and decent and very seldom tend to crack very very slightly only if you listen with a very keen ear,you wont notice it otherwise!.Now there is a very important thing about these phones that i found about as i used them,You need to get the correct fit to understand the true capability of the drivers. Which is somewhat difficult sometimes since the design is a bit weird with the angled drivers and all,which philips claims to deliver better sound directly to the ear drums.Frankly,i found it a bit uncomfortable to wear,might be a new earphone thing and might take some time for my ears to get used to. But not as comfortable as my first pair of in-ears my JVC fx-33Bs! I really Miss them!

One thing i really like about the headset is ,it has small bumps on the left earpeice. This helps you to recognize the left and the right earphone even in the dark. This is

Final Words: Really good bass,OK mids and highs.OK build quality,Crappy volume control,takes some time getting used to the fit,great compatibility with almost all modern smart phones on the planet(including the iPhone!).Great value for the Price!

Let me know what you think about it in the comments below!! :)

Update:Tested the headset with a a bunch of phones here’s the result

Phone                                         Result

iPhone                                        Works pretty Well.

Samsung Galaxy S i9003       Worked well. Without the bundled adapter. (The adapter was meant for samsung ,nokia and sony ericsson phones!)

Sony Xperia S¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬†¬† Did Not Work ,even with and without the bundled adapter a ‘headset incompatible ‘message shows up!.I was expecting it to work.

The package did not mention anything about this! They should’ve specify the exact phone models that are compatible!

Motorola Atrix2 reviewed

Motorola launched the atrix 2 in india late last month. Almost six months after they launched it in the US.

It seemed like a good vfm phone given the market price of around 22,000 INR and the many positive reviews all around the internet made it seem like an awesome buy!!!

So i thought i should check it out.I ordered it,from probably india’s answer to amazon flipkart. it arrived 3 days post order. Packed snuggly in couple of layers of bubble wrap which i enjoyed popping! :P.

Lets open it up and check it out!

The atrix2 comes with pretty standard stuff inbox. A 2gig micro sd. A pair of earphones , that i will probably never use! A data cable. A charger with a USB socket. So that you can directly plug in your datacable into the charger and it becomes the charging cord! Most manufacturers now-a-days ship phones with a female usb so that people can just plug in the datacable itself and charge their phones!! I think its cool! The battery that comes with the phones a li-po battery with a capacity of around 1785mAh max(1735 mAh Typ.)! Thats awesome and reviews everywhere say that the large battery really helps a lot in keeping the phone alive and kicking for like more than a day,  and with super heavy use! Infact the big battery and the dual core processor were the biggest factors that made me go for this phone!

As i said the phone is powered by a dual core processor. Infact the phone is based on the TI OMAP4430 chipset with 2 arm-cortex A9 cores!! And the gpu is a powervr SGX540. The hardware was able ti handle 3d games pretty easily! I tested the 3D capabilities with the bundled EA games that came free with the phone. Dead space looked stunning and i was able to play the game without a single frame being dropped!
I also ran a few benchmarks with the Quadrant Standard Benchmark. And It scored a decent 1756. and Even bettered the galaxy nexus in the 3D scores.

The Sound quality was decent.The true Quality was not evident with the bundled Headset. But Sounded good on my Skullcandy Inkd Ear Buds.

The Display Is a qHD 960×540 TFT. The resolution and Pixel density is awesome .The colors appeared a bit yellow. Sunlight Visibility was okay. Overall the display is ok ,but a better quality display would have been much appreciated.

The Phone also Supports USB HOST.But i haven’t tried it out yet .Will be trying it out soon. And i will post about it soon,as soon as i’m done.There’s also a mini HDMI Jack for connecting to a monitor or a TV set. The cable is not bundled with the handset.

There are two camera one on the front for video chat and another on the back .The rear Camera has a 8Mp Sensor and has a single LED flash.Low Light performance is ok. Better than Most cameras. The images can be shot in various modes and at various resolutions. I liked the widescreen Image option Where the image is shot at a widescreen aspect ratio. and the resolution is around 6Mp.Full HD Videos can be Shot With the camera.Here’s a Sample of a Video that i took with the camera. (Thats Hemanshu Playing the bass Cover for Billy jean in the video).Videos Came Out Pretty good at 1080p ¬†and even at lower resolutions.Even at night the videos Came out pretty decent.Infact I think the videos came out better than the Images shot in low light!


The Phone Comes with android gingerbread 2.3.6 out of the box. And a ICS update for the Asia pacific model (the models available in india) is expected in 3q 2012. That’s actually pretty late considering that most devices will be getting their ICS updates in 2q and there are already devices running Android 4.0 in the market!

Moto phones are bundled with their Custom version of the Android UI called MOTOBLUR,which i really like ,Much better than Samsungs Touchwiz UI which Is more like a clone of Apple’s UI. and even HTC SENSE which i don’t like at all.

The default Music Player App is Actually great in some aspects. It fetches the lyrics asn album art for you as the song is being played. It does not save the lyrics though hence to enjoy the lyrics you will need internet connectivity when the song is being played.It uses Tunewiki for fetching the song info.

There also this thing called the Universal inbox.Its basically a Place where all your unread Fb messages and texts are displayed in a single widget.Kinda Cool but haven’t used it much yet.

The Phone has on-board storage of like 8Gb. But it cant be used to store data files. Only application data Can be stored.Rooting can probably Solve this ‘issue’ and allow the on-board storage to be used more efficiently.

The Lock Screen interface is nice and i really like it.

There is Also the motorola phone portal that allows to sync your phone with your PC not only over USB but alos using wifi!! That’s actually Neat! You can manage all your data ,contacts and message .Using a simple Browser Interface. Internet explorer is the only browser supported to allow data Management though! :(.Other things such as Contacts and Messages can be managed with virtually any browser.

The Dialer interface and contacts app Kinda Sucks and takes time getting used to. And Unlike in HTC devices the Contacts from different sources such as facebook,twitter and your phone book are not merged but appear as separate contacts! WTF??. The Contacts App implementation of HTC was way better in this aspect!.It used to  give me contact match suggestion and it even merged contacts from various sources automatically. So that if a person in on  FB,twitter and Also is in my phone book.It appears as a single Contact. Instead of Multiple contacts!!!

You get 5 Customizable home screens.The Other UI elements are pretty much standard Android nothing much to add in this department!


The Size of the Phone is perfect and Fits snuggly into your palms. The back of the phone is Rubberized and has a fabric like texture to enhance the grip.

4 standard Android Keys are present at the bottom of the LCD.

The Key placement should is a bit too close to the edges and would have been better if it was placed a bit higher. The Keys get accidentally activated when typing with both hands. And can interfere and reduce the typing speed drastically!. I strongly recommend some sort of body cover for this phone.The Phone Seems Slippery,Especially when using it single-handed.I used a silicon jelly case from amzer. It improved the usability drastically!.And Also got a more comfortable grip on the phone.

The Earphone jack is the Worst part of the design,i feel. I tends to scratch the surface of the earphone Plug . I tried it with a couple of earphones. And the Plugs of both the Earphones were scratched badly!.I really hate it very much!

The rocker keys for the volume and the camera key on the side of the device are wedge shaped and have a sharp edge.Its a bit difficult to press them  due to the shape. But i guess  one can live with that as its not that bad actually!

Bottom line: The Real Good stuff :battery life ,qHD display, awesome Hardware,Decent Camera. The Let Downs The Silly Earphone Socket,the Display Is a TFT-LCD(Blacks are usually just grays,If you own a phone with an AMOLED display You will Find the display weird because of the poor contrast ratio),The Phone’s Design really makes typing with both hands in landscape Mode difficult.The rocker keys at the side could have been better designed,the phone lacks grip and hence neccesitates a body cover fro the phone

This Video Review Helped me a lot in making my decision but i think they didn’t cover the downsides of the device well .
[youtube http://www.youtube.com/watch?v=OhRz6UCm7hQ]

Disclaimer: All the views expressed are totally based on my personal experiences and i am not affiliated to nor was paid by any of the organisations/companies mentioned in the above post.

Dangerous Prototypes Bus Blaster Build

I had Received a free Coupon from Dangerous Prototypes as a part of their Free PCBs Contest.I chose to get the Bus Blaster PCB. Since i was really needed a JTAG debugger my lpc1768 blueboard. Just Completed the Build. Check it out! Soldered the FT2232 using the drag soldering method.Had to remove some stubborn solder bridges formed during the soldering of the fine pitch QFP using a razor blade! Thanks Ian and Dangerous Prototypes! :)

UPDATE: Here are some More Pics of the Bus Blaster!!

The Dangerous Prototypes Sticker goes well with the Navy Blue Lid of my Laptop!