Solenoid
A solenoid moves an iron core through the center of a wire coil when current flows through the coil. It is different to a relay which uses an electromagnet with a fixed iron core. Typical voltages used in solenoids are 12 and 24 volts. Some solenoids are controlled by pneumatic and hydraulic pressure instead of electricity.
Solenoid Actuators
Solenoids actuators have a spring in the base at the base of the iron core. When current flows through the solenoid, the electromagnetic field overcomes the spring resistance, and pulls the rod through the center of the solenoid. The spring pushes the rod back out when the current stops flowing. This push-pull action is used to control many common devices such as locks and valves.
Starter Solenoids
Solenoids are used to control the starter motor in virtually every automobile. When the solenoid is energized by turning the ignition key, a conductor is pulled against two terminals, and a large current flows from the battery to the starter motor. It also moves the drive pinion to connect the starter motor gear with the engine flywheel. When the ignition key is released, the spring pushes the conductor off the terminals and stops the starter motor, and also disengages the pinion gear.
Troubleshooting Solenoids
If a solenoid fails to move back into place when the coil current stops flowing, the spring in the base may be broken. If a solenoid makes a continuous clicking sound, the current is insufficient to create a field strong enough to keep the the spring compressed. This may be caused by a short in the coil that is preventing current from flowing through all the coil turns.
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- Relay
A relay is a remote switch controlled by current, magnetism, or temperature. The relay was invented in 1835 by Joseph Henry (1979-1878), an American scientist. Relays are a common component in many devices, and there are many different types of relays. Relay Types The two main types of relay are electromechanical and solid-state. Electromechanical relays [...]...
- Inductor
An inductor is a conducting coil, wrapped around a core, that creates inductance when an alternating current flows through it. Inductors are used to impede the flow of current in a circuit. The conductor is usually thin magnet wire, and the core is usually air or steel. Working of an Inductor When the alternating current [...]...
- Rheostat
A rheostat is an electrical component that has an adjustable resistance. It is a type of potentiometer that has two terminals instead of three. The two main types of rheostat are the rotary and slider. The symbol for a rheostat is a resistor symbol with an arrow diagonally across it. Rheostats are used in many [...]...
- How Wireless Power Induction Works
Wireless power induction is already being used today in the form of electric toothbrushes. An electric toothbrush contains coils or loops in the toothbrush handle as well as in the base recharging unit. Because of their constant exposure to water, electric toothbrushes have to use inductive coupling as a means of recharging their batteries. Inductive [...]...
- Electromagnets
Electromagnets are magnets whose magnetic properties come from or are generated through electricity. A magnet is a material (this is usually metal), which has at least one pair of negative and positive poles. These opposite poles' attraction produces a magnetic field. This gives the magnet the ability to 'attract' metals such as iron or steel. [...]...