Introduction: Recycled Hard Drive Clock - FuneLab
This is my fifth project on Instructables & Thanks everyone liked this.
You have a broken hard drive? You would put it in the trash or sell it on Ebay for a few dollars? Oh no!
Get ready to turn your crashed hard drive into a unique clock. This project only requires a little skill, your ingenuity and a little knowledge of electronics.
This work is based on Ian Smith's version of the same. His work is excellent, and his website on this topic will help provide a complete picture for this instructable.
You can search with keywords "HDD Clock" or "POV clock" to see the unique clock from the hard drive.
In this project I have two versions of HDD Clock: a simple version and another version showing the number.
In the simple version, you can see three hands of the clock looks like mechanical watch. Yes! That is the hour hand and minute hand second hand. But you can not distinguish them by short hand or long hand. You must distinguish them by color. Red for the hour hand, the minute hand green and blue for the second hand.
So how a hard drive can be displayed like that?
The platter of a hard drive spins well over sixty times a second. If a narrow slot was cut into the platter to allow LEDs to shine through, we can achieve flicker fusion and trick the eye into seeing a stable image. This phenomenon is known as persistence of vision (POV). There are many examples of LEDs being used for POV, building an image by moving the LEDs or having the observer move relative to them. The LEDs used in this project do not move, and the image is built using the interference of the slotted, spinning platter.
Version clock can display the number seems more complex. You can easily see the time and it also displays the animation, I will present in another project.
Step 1: Intro
The system works by timing the slot in the platter. The microcontroller uses an internal timer to clock each revolution. It achieves this using an Hall sensor, which triggers a hardware interrupt on every full revolution of the platter. The microcontroller uses the revolution time and phase to schedule a second internal timer. This second timer uses an interrupt to schedule the timing of the LEDs, firing tens of thousands times a second to build a stable, visible image.
For under $ 60 you can build yourself a HDD clock. It is compact and does not cause strong noise when in operation.
Step 2: Materials List
Here is what you need to make your HDD clock:
- a corrupted laptop hard drive 2.5 "
- 30-40W soldering iron with small tip
- 3mm Screws Hexagon and Screwdriver
- Drill bits
- Super glue
- Hot glue and it's gun
- 0.5m of 5050 RGB LED strip (Better you should buy one meter).
- AH175 Hall sensor
- ATmega8A SMD
- DS1307 SMD
- TDA1540AT SMD
- 3V Battery holder
- 12VDC 1A power adapter
- DC jack 3 pin
- LM2596 SMD
- 5-way tactile switch
- 2-pin button SMD
- Coil, capacitors, resistors, LEDs, transistors, headers, wires, crystal
- ...(in schematic file)
Acrylic for case and platter.
Step 3: Remove a Hard Drive
Select a hard drive, and open the top case. Opening a hard drive requires a set of Torx screwdrivers. If you don't have any, you can pick up a set at any well stocked hardware store.
I use a hexagonal screwdriver to open the lid of the hard drive, this is fairly easily.
Next, disassemble all the components of the drive. Once you remove the top case, remove the entire read/write assembly.
Remove the platter retaining collar, and remove the platter stack. Make sure you save the collar, its screws, any spacers and any platters. Note: keep the reader's hard drive is not broken.
In the hard drive magnets have strong magnetic fields, you should leave it away from electronic equipment to avoid potential interference.
Let all the components (except the hard drive bracket) in a sealed box dust because you will reassemble them later.
Step 4: Drilling
Using 3mm and 5mm drill bit to drill holes in the same location as in Fig. You will pull the LED and the sensor wire through this holes.
Step 5: Wiring the BLDC Motor
The motor is mounted hard drive BLDC motor (Brushless DC Motors). This motor has 4 pins include: COM, MOT1, MOT2, MOT3.
I used 4 small wires to solder into 4 pins of the motor. They will be connected to the motor driver IC.
The weld is very small and easy to break, so I fixed it with hot glue.
Step 6: Hall Sensor
Hall sensors are important components, you have to put it near the edge of the platter where the magnet attached to generate a signal to the microcontroller.
Hall sensors AH175 has 3 pins: one for GND, one for VCC and one for Signal pins.
Using a pull-up resistor 10k Ohm to ensure that inputs to microcontroller settle at expected logic levels.
Solder sensors on a small circuit board with a hole drilled to screw fixed position.
Step 7: RGB LED Strip Testing
In order to achieve the best effect, you will want to fully encircle the underneath of the platter with the LED strip.
I use 5050 RGB LED strip, you will easily buy it on Ebay for cheap. There are 60 RGB LEDs per meter.
If you are using a standard 2.5" drive, then your platter chamber should accommodate 12 LEDs.
The LED strip can be separated into groups of three. Cut out one section of three groups. Do not separate the tape into three groups. You want one piece of tape with 16 LEDs. This should leave a reasonable gap for the platter sensor, where the read/write assembly used to sit. Make sure you cut the tape on the line between copper tabs, or else you may severe internal traces rendering the affected section useless.
If you don't have wires pre-attached to the section you wish to use, you will need to solder on wires. Identify the red, green, blue and 12V lines, and solder four wires to the copper tabs. It's best if you tin the copper pads before soldering the wires. After you attach your wires, be mindful of the stress you apply to the solder joints, they can easily break. Test your work using a 12V supply.
Step 8: LED Ring Attached to the Hard Drive
Before installing the LED strip on the drive, you have to put wire through the holes first. Then solder the wires to the LED. Be careful to not breaking the copper contact points.
When affixing the LEDs, you shouldn't trust the sticker backing provided by the manufacturer. It just isn't strong enough. Get some super glue, and slowly glue the strip to the chamber wall, pressing firmly as you proceed. It's imperative the LEDs are affixed as straight and flush as possible, so work slowly and carefully.
Step 9: Make Your Clock White Background
Most hard drives are finished with a black matte. It is not a conducive background for our LEDs, so we need to make a more reflective backdrop.
Grab a piece of thick, white paper (Photo Paper for Inkjet Printers) and trace the outline of a platter (both the inside and outside). Cut out your paper platter, and widen the central hole a few millimeters. Slip this over the spindle, and push it down to the floor of the platter chamber. You might need to trim the paper a little so it doesn't rip. This will serve as a white, reflective backing, making the color in your LEDs shine more vibrantly.
Once the backdrop is positioned, make sure the spindle can still spin freely. If it can't, trim the center hole of your backdrop.
Step 10: Attaching Hall Sensors to Your Hard Drive
Once you have your sensor ready and wired, test its position before you attach it to the hard drive chassis. An oscilloscope is ideal for this, but a volt meter can work just as well. You want to make sure that the sensor position provides a high fidelity signal when its index (magnet) passes by.
Once you are happy with its placement, just fixed it by a hard plastic screw.
Step 11: Power and RTC and Buttons
Because HDD clock needs a large current to supply the motor and microprocessor, should I use IC LM2596 5V 3A.
You can easily design a simple circuit with a current source power by LM2596 and a few other components.
LEDs require 12V voltage, you must use the 12V DC adapter for LEDs operate with maximum brightness. 5V supply output for microcontroller and motor activity.
I have used a 5-way switch. You can see pictures of it above, this type of switch is compact so it's flexible so I can design a circuit board easily. It has all 10 pins, including four pins Common, two pins Center to press down and four pins left for the remaining four directions (right, left, up and down).
On this switch, I press in the center to function Set /OK, press to the right to go to next setup, press the left to go to previous setup, press Up to increase the time/date/month, and finally press down to decrease the time/date/month.
Real Time Clock (RTC):
What is an RTC? A real time clock is basically just like a watch - it runs on a battery and keeps time for you even when there is a power outage! Using an RTC, you can keep track of long timelines, even if you reprogram your microcontroller or disconnect it from a power plug.
The RTC I'll be using is the DS1307. It's low cost, easy to solder, and can run for years on a very small coin cell. As long as it has a coin cell to run it, the DS1307 will merrily tick along for a long time, even when the the clock loses power, or is reprogrammed. You MUST have a coin cell installed for the RTC to work, if there is no coin cell, you should pull the battery pin low.
Step 12: HDD's BLDC Motor Controller
TDA5140AT is dedicated IC to control the BLDC motor. You have to design the circuit with the correct parameters to the manufacturer's datasheet, it's a little of my experience of the BLDC motor. You can buy this IC on Ebay for under $ 7.
I have used this IC some time and realized that it was noisy when you put the device aired too close. When you call, motor may stop spinning and sounding "ek ek ek ...", controller chip is also heating up quickly after that. The solution is to add the filter capacitor close to the IC power pins.
Step 13: Schematic
I finished the schematic and saved as .pdf files
You can download this pdf file, or use Eagle software to view.
Step 14: Eagle Board
I've designed two-layer printed circuit to fit it when attached to the back of the hard drive.
You can see by Eagle Software version 6.4 or higher.
Step 15: Order PCB Board Online & Wait
After the design is finished printed circuit, I send the file to a printed circuit machining company in China. Wait about 3 weeks to get the circuit back, looks really great quality. about $ 45 for this.
If this is your first online ordering of printed circuit, it seems complicated when choosing the parameters of the PCB and you will not worry if the waiting time is too long. However, just trust that your order will arrive on time. Be careful when you set up the parameters of the PCB, if there is any mistake, you should email the PCB company to fix when they could.
Step 16: Soldering Components Onto the PCB
Most of the components on the PCB are SMD type, so you'll need a good soldering skills to do this.
Remember to use flux when welding to weld looks perfect, clean the excess flux with water to wash the PCB.
You should solder LM2596 power block first, then check the output of 5V to avoid short-circuit.
Step 17: Laser Cut & Carving
I have also designed a case for HDD clock by acrylic. The design is simple with Corel Draw, but I have to carefully calculate the size to fit panels circuit board placed in the case.
I used 2mm and 5mm thick acrylic sheet to make the case for HDD clock. This is necessary to prevent noise from the drive motor, the case also protects you in case your hand touching the rotating disk.
Here are a few pictures of my acrylic sheets after laser cutting at a store.
The cut is completely accurate and smooth, looks very nice.
If you have a laser cutter, this is done with relative ease. If not, please send your file design to a rental shop for laser cutting machine, you will get the case soon after. Note carefully measured the dimensions of case design to fit in your hard drive
Step 18: Mounted Acrylic Disc to Hard Drive
I have black paint the platter, this increases the contrast of the display area, so you can clearly see the LED strip inside. Carefully assembled it on the spindle of the motor drive. You should try to place the platter was calibrated before tightening the screws. If the disk location is skewed too far to the spindle, when motor is rotating will cause a very unpleasant sound.
Step 19: Reassemble the Parts in the Hard Disk
Now take the components of the hard drive that you removed from step 3, assemble it back together. You can leave the magnet to look better.
These components are easily oxidized, so make sure you dry your hands before touching it, sweat in your hands can make them worse.
Make sure you tighten the screws so they do not fall out when the motor is turning.
Step 20: Fixed PCB
I use a plastic hexagonal screws for fixing the hole printed circuit boards snails available on the hard drive.
Step 21: Wiring
Next, I wired into the motherboard include:
- Motor cable
- Sensor cable
- LED strip
You should note the wires connecting the right position so as not to cause a short circuit.
Step 22: Mounted LED Background
To clock looks classy and eye-catching evening, I added the LED backlight behind the hard drive.
The lights will illuminate the bottom floor where you place the clock.
I take advantage of groups of three LEDs from the unused portions of the LED strip and solder the wire to it, then fixed to the LEDs on the back of the hard drive.
Step 23: Upload Firmware to Board
The source code is provided below. Download the code, and compile it in your local WinAVR environment. The code for the firmware is heavily commented, which should make it easy to hack.
Step 24: Assembly HDD Case
Step 25: Special Edition
The special edition of HDD clock with digital display, it can display the day, month, year and temperature. Alternatively, you can write the words on it.