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Messier 69 or M69, also known NGC 6637, and NGC 6634, [9] [10] is a globular cluster in the southern constellation of Sagittarius. [a] It can be found 2.5° to the northeast of the star Epsilon Sagittarii and is dimly visible in 50 mm aperture binoculars. The cluster was discovered by Charles Messier on August 31, 1780, the same night he ...
The key feature of the Ward Leonard control system is the ability to smoothly vary the speed of a DC motor, including reversing it, by controlling the field and hence the output voltage of a DC generator, as well as the field of the motor itself. As the speed of a DC motor is dictated by the supplied voltage, this gives simple speed control ...
A motor controller is a device or group of devices that can coordinate in a predetermined manner the performance of an electric motor. [1] A motor controller might include a manual or automatic means for starting and stopping the motor, selecting forward or reverse rotation, selecting and regulating the speed, regulating or limiting the torque, and protecting against overloads and electrical ...
An electronic speed control follows a speed reference signal (derived from a throttle lever, joystick, or other manual input) and varies the switching rate of a network of field effect transistors (FETs). [1] By adjusting the duty cycle or switching frequency of the transistors, the speed of the motor is changed. The rapid switching of the ...
The Butterfly Cluster (cataloged as Messier 6 or M6, and as NGC 6405) is an open cluster of stars in the southern constellation of Scorpius. Its name derives from the resemblance of its shape to a butterfly. [5] The first astronomer to record the Butterfly Cluster's existence was Giovanni Battista Hodierna in 1654. [6]
Dahlander motors have advantages compared to other speed control systems like variable frequency drives, as there is less power loss. This is because most of the power is used to drive the motor and no electrical pulse switching is done. The system is much simpler and easier to use compared to other speed control methods available.
Messier 71 (also known as M71, NGC 6838, or the Angelfish Cluster) is a globular cluster in the small northern constellation Sagitta. It was discovered by Philippe Loys de Chéseaux in 1745 and included by Charles Messier in his catalog of non- comet -like objects in 1780.
Messier 66 or M66, also known as NGC 3627, is an intermediate spiral galaxy in the southern, equatorial half of Leo. It was discovered by French astronomer Charles Messier [ 8 ] on 1 March 1780, who described it as "very long and very faint". [ 9 ]