Step 1: History
In an experiment, I connected a loose HD to a computer power supply, and felt the resistance to its change of position. I figured a HD in the horizontal and one in the vertical plane (X- and Y- axis) would dampen almost all unwanted shaking.
The 2 Gyro stabilizer model is very successful, but practical use of the device is limited, due to bulk and weight.
A single Gyro has its theoretical limits. A strong Gyro in the front / back plane (Z - axis) could dampen shaking, but would not correct rotation. But if rotation around the optical axis is only a minor component of motion blur... , the advantage is less weight and power requirement.
Step 2: Design
The camera is mounted on a hinge with fastening screw. The other part of the hinge mounts a HD.
The HD can be tilted in the vertical ( Y-) plane from way under the camera to a hugging position for storage.
(my understanding of...) the theory would indicate the best position of the axis of rotation is parallel to its optical axis.
But in this design, any position of the HD Gyro can be tested. It also makes storage and transport much easier than the 2 Gyro model.
Step 3: Materials
For the gyro I had a 80 Gb 7200 RPM single platter HD, still in use for external backups.
2 USB car phone chargers convert the 12 V lead cell input power into 5V, 800 mA max. (HDs need both 5 and 12 V, the newer SATA HDs need 3.3 V as well).
A simple hinge has the pin taken out. Instead a piece of M8 thread holds the hinge together. A small tube is put over it as a spacer and a knob at the end allows fixing the hinge in any desired position.
A small plate of aluminum is attached to the camera side of the hinge, to provide space for the HD in park position (not too thin, think about stability!).
A piece of poplar wood, from one of them knicknack wooden boxes, covers and protects the delicate backside of the HD.
Step 4: Electronics
A HD needs 2 or 3 voltages (3-4 leads) to function( 12V, 5 V, the newer SATA disks also 3.3 V, and of course ground/ 0V).
Most older HDs, the ones with a Molex connection, only need 12V and 5V. Although the spinning motor needs only 12 V, the HD won't work unless it is supplied with both voltages.
Power requirements for any model HD can usually be found on the sticker at the top of the HD, or on the manufacturers' site.
Cheap (2 E) USB car phone chargers transform 12 V DC into 5 V DC. The output of a single charger is ca. 400 mA.
2 of these chargers were wired in parallel, to meet the start-up power spike requirements (the arm of the HD only makes a few moves during start-up; afterward it doesn't do nothing).
My power supply is a small 12 V lead acid battery. A ca. 1m (3 feet) flexible wire ending in a car 12 V socket supplies it to the device. The battery can be worn in a small shoulder bag or on a waist belt. Plugging it in or out is the 'on/ off' switch.
(Other types of 12V batteries are possible as well; with a setup looking quite different).
The car phone chargers come in a ' car plug' format. After the circuit boards were soldered in parallel, one plug was left intact, while part of the housing of the other one was put behind it. Some hot glue, duck-tape and a piece of bike inner tube made it more sturdy : almost like a laptop power supply!!!
Step 5: Testing
The old (finished Sept 24th) 2 Gyro system provides a great stabilization, but is quite bulky. Not that easy to take into the field...
This 1 Gyro design is far more easy to handle in the field, cheaper, folds up, stores easily, uses less power and is easier to build.
Testing was done during mid twilight. The camera was a Canon SX 110 IS, at 10X maximum zoom setting (330 mm focal length 35 mm equivalent).
Exposure was set at 1/ 15 sec: Impossible to avoid motion blur if held by hand.
DISCUSSION OF RESULTS:
With some training, this stabilizer performs almost as well as the far more bulkier 2 HD stabilizer.
Training is important: Holding the camera in a steady, horizontal (unrotated) position is easy. But when pressing the shutter button, a beginner like me tends to move his whole arm instead of just his finger. Which results in rotation of the camera...
Rotation around the optical axis is the only unstabilized motion in this design.
Fortunately, with some practice, pressing the shutter button while holding the camera steady, is easily learnt.
I would have preferred the multi platter HD. The gyro power of this particular HD feels a bit light.
Step 6: Possible Further Improvements
1) Making a strap: too many devices! Camera, battery, stabilizer and bag. After use, stuff needs to be taken apart and stored. Normally, the 'feel' of the camera weight make sure things are properly taken care of. The presence of yet another device is hard to notice. This confusion makes it easy to drop things (I almost dropped it when taking the camera off)!
2) The HD could be be protected by rubber or insulation foam strips. A serious, multi- platter HD can carry many images, videos or data, as an 'image tank'. Wiring kits to convert the HD into an external storage device are cheap. But, if taking the stabilizer into the field, one should really have another backup... (Of course, this depends somewhat on what one considers ' the field': is it your back yard or a war zone?).
3) Making sure all connections are tight and water proof.
On stronger motors: CD/DVD and HDD spindle motors are being hacked by the RC model plane community. With thicker wiring and replacing the ceramic magnet ring with Neodymium magnets they seem to reach up to a whopping 400 W output. Machining of a new rotor (bell) and controller ('esc') is required +a high output battery pack (LiPo), which would make a gyro project no longer low budget nor fast to assemble. It could provide another dramatic reduction in size and weight though. Link:www.flyelectric.ukgateway.net/machin.htm