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A DC motor is an electrical motor that uses direct current (DC) to produce mechanical force. The most common types rely on magnetic forces produced by currents in the coils. Nearly all types of DC motors have some internal mechanism, either electromechanical or electronic, to periodically change the direction of current in part of the motor.
Lester Don Holt Jr. (born March 8, 1959) [3] is an American news anchor for the weekday edition of NBC Nightly News, NBC Nightly News Kids Edition, and Dateline NBC.On June 18, 2015, Holt was made the permanent anchor of NBC Nightly News following the demotion of Brian Williams.
When the electromagnetic clutch is used in automobiles, there may be a clutch release switch inside the gear lever. The driver operates the switch by holding the gear lever to change the gear, thus cutting off current to the electromagnet and disengaging the clutch. With this mechanism, there is no need to depress the clutch pedal.
A brushless DC electric motor (BLDC), also known as an electronically commutated motor, is a synchronous motor using a direct current (DC) electric power supply. It uses an electronic controller to switch DC currents to the motor windings producing magnetic fields that effectively rotate in space and which the permanent magnet rotor follows.
The leads of the switch must be handled carefully to prevent breaking the glass envelope. The glass envelope can be damaged if the reed switch is subjected to mechanical stress. Most reed switches are filled with nitrogen at atmospheric pressure. After the final seal is made, the switch cools and the internal pressure is less than one atmosphere.
The most widely used electronic switch in digital circuits is the metal–oxide–semiconductor field-effect transistor (MOSFET). [2] The analogue switch uses two MOSFET transistors in a transmission gate arrangement as a switch that works much like a relay, with some advantages and several limitations compared to an electromechanical relay.
A Single-Pole, Single-Throw (SPST) mercury switch on millimetre graph paper, device length approximately 1.5 cm Another mercury switch design. A mercury switch is an electrical switch that opens and closes a circuit when a small amount of the liquid metal mercury connects metal electrodes to close the circuit. There are several different basic ...
In a switch where the contacts remain in one state unless actuated, such as a push-button switch, the contacts can either be normally open (abbreviated "n.o." or "no") until closed by operation of the switch, or normally closed ("n.c." or "nc") [nb 1] and opened by the switch action.