Microcontrollers are everywhere, including the oddest of places,such as a razor—the Schick Hydro Power Select customizablepower razor, to be precise. I’m not sure why you’d needmicrocontroller-controlled customizable power or the packaging,waterproofing, and power issues that go along with it, but I gave ita shot. After all, Schick promises it “allows men to interact with their razor in anew way.” I never realized that I longed to interact with my razor in new ways,but Schick has created a demand—a craving, if you will—and I just had to try it.Alas! It wasn’t all that much better than interacting with my regular arm-powered,hand-controlled razor, so I instead took it apart. It’s a bit more interestingto go inside and see how the designers implemented a wet razor, powered fromone AAA battery and featuring three vibration settings, easy-to-read indicators,and a haptic sensor. Why they would do it is another question. Microcontrollers are everywhere, including the oddest of places,such as a razor—the Schick Hydro Power Select customizablepower razor, to be precise. I’m not sure why you’d needmicrocontroller-controlled customizable power or the packaging,waterproofing, and power issues that go along with it, but I gave ita shot. After all, Schick promises it “allows men to interact with their razor in anew way.” I never realized that I longed to interact with my razor in new ways,but Schick has created a demand—a craving, if you will—and I just had to try it.Alas! It wasn’t all that much better than interacting with my regular arm-powered,hand-controlled razor, so I instead took it apart. It’s a bit more interestingto go inside and see how the designers implemented a wet razor, powered fromone AAA battery and featuring three vibration settings, easy-to-read indicators,and a haptic sensor. Why they would do it is another question.

1. A three-stage power buttonsets the vibration. The razorrotates through all threesettings and then goes intooff mode. It required toomuch pressure to activatedue to its sealing cap.

2. A vibration-stageindicator usesLEDs.

3. Batteries are inserted here.





4. Removing thecap exposesthe AAA battery.These batterieshave a peakvoltage of 1.8Vbut drift down to0.9V over time.

5. The batteryholder attachesfirmly to thePCB using asolder jointand clips.

6. The internals, with plastic and rubber sealing removed,expose the unbalanced motor that vibrates the razor.Unlike a toothbrush motor with an actuator that rotatesthe heads, this motor doesn’t connect to the razorblades. It simply causes the razor to vibrate. If anyonehas found this vibrating feature on a razor to be useful,please let me know. I may be missing something.

7. The razorhas athree-stagepowerswitch.

8. A Microchip MCP1624 low-voltageinput regulator boosts thebattery’s voltage to the 2V thatthe Microchip PIC10F222 microcontrollerrequires. The regulatormaintains that 2V over the life ofthe battery, even as it drifts overtime from 1.8 to 0.9V.

9. At the heart of theHydro Power is thePIC10F222 microcontroller,again fromMicrochip. This six-pin,8-bit device has 768bytes of flash memorythat sells for 40 to79 cents (www.datasheets.com). It controlsalmost everything,including the motor,through an on-chipPWM controller.

Editor's Note: A friend of mine was kind enough to provide more details and pointed out some items I forgot to mention above, such as the motor being a precision metal-brush dc motor.But wait, there’s more, a lot more: Here is a board breakdown, followed by a functional description of the overall module:

The module can be split into the following parts: The module can be split into the following parts:

Battery

dc/dc converter (raise/conditioning of battery voltage)

Microcontroller

Software

Peripherals (switch, LEDs, motor)

Other components

Battery:

-AAA-size battery was selected due to size, acceptable weight, sufficient capacity, availability worldwide

dc/dc converter (raise/conditioning of battery voltage):

-Raise of battery voltage 0.8 to 1.6V to stable 3.0V

-Allows use of battery’s capacity up to 80%

-3.0V required to run LEDs and microcontroller

-Stable/distortion-free power supply for the microcontroller

-Stable reference voltage supply to determine battery status

-Minimal continuous power consumption of approximately 70 μA (in sleep mode)

Microcontroller:

-The architecture of the 10F-microcontroller family from Microchip meets our requirements regarding size, cost, flexibility

-Reliability, and power consumption: The microcontroller hosts the prepreprogramed software and controls the components based on the user interaction and the battery status

-When the battery is inserted the microcontroller is always on:

mode: software execution mode according to programmed commands mode: sleep mode, minimal power consumption, waiting for user switch action then going to 1. mode



Software:

-Motor speed adjustment and corresponding LEDs

-Device on/off, sleep mode

-Battery-life indication

-Auto switch-off to sleep mode after 13 minutes run time (protects device from accidental turn-on)

-Power-up sequence: self-test when changing the battery (short pulse on all LEDs and motor)

Peripherals:

-One micro push button for start/stop and select speed (this pulse switch type is not cutting off power supply)

-Three green speed LEDs show the selected speed of the motor (low, medium, high)

-Two battery LEDs indicate the battery status:

green = battery ok red continuous = a few shaves left red flashing and no motor = change battery at battery exchange: battery reset to green at battery voltage > 1.35V

-Low power consuming 1.5V-dc vibration motor



Other components (resistors, transistors, capacitors, diodes):

-Only a few other low-cost components are needed to: