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In order to explain the steps, you can take to minimize perceived turntable vibration, it is important to first understand the different turntable and motor mechanics.:
- First, the motor types. There are two types of Iconasys turntables:
- The first design uses a DC or AC motor, together with an encoder that tells where the turntable is located. This design, which Iconasys called the "USB Turntable," was used in the original Iconasys turntable and it's no longer being produced. The advantage of the DC motor design is that the motor tends to have a smoother rotation, but the design becomes more complex in determining the turntable position. Further, it gets a little trickier with trying to stop the table at the exact position.
- The second design is based on stepper motors. All existing Iconasys tables, including the Silver and Platinum series use a stepper motor. The advantage of stepper motors is that they can be made very precise, without much circuitry. On every controlling pulse, the motor makes a small update in position. In order to rotate a stepper motor, multiple square pulses are sent to it. At each pulse the motor updates one step. The motor speed is controlled by the frequency of the pulses sent to it. Because the stepper motor updates its position in steps, stepper motors are inherently less smooth than a continuous DC motor design. A good way to visualize the movement between the continuous motor and the stepper motor is to think about the seconds hand on a smoothly rotating clock versus a digital clock. In a digital clock, the seconds hand has discreet movements, with the hand jumping from position to position.
- Second, the stepper controller logic. When designing the stepper controller logic, there are two possible approaches.
- The first approach is to use an off-the-host controller. In this case, a second "mini-computer" is used to offload the step-pulsing responsibility. Commands are sent from the main computer to the mini-computer and the mini-computer handles the pulsing of the stepper table. The advantage of this approach is that pulsing the turntable is independent of the host computer and the main capturing program can be placed in the background, without affecting the turntable rotation. The disadvantage of this approach is that if there is any upgrade that needs to be done to the "mini-computer" the upgrade, often referred to as a "firmware upgrade" is more complex and the min-computer can easily end up in a vegetable state if the computer loses power or connection during the upgrade.
- The second approach is to use an on-the-host controller. This eliminates the need for a second "mini-computer" and significantly simplifies the upgrade logic. A new update requires a new software install on the main computer and everything works. The disadvantage of this approach, however, is that if the main turntable controller software is put in the background and the OS no longer prioritizes the pulses to the table, then the table can shake or stutter.
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