Resistor

Resistor

    A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active elements, and terminate 

Diode

Diode

                      A diode is a two-terminal electronic component that conducts current primarily in one direction (asymmetric conductance); it has low (ideally zero) resistance in one direction, and high (ideally infinite) resistance in the other. A diode vacuum tube or thermionic diode is a vacuum tube with two electrodes, a heated cathode, and a plate, in which electrons can flow in only one direction, from cathode to plate. A semiconductor diode, the most common type today, is a crystalline piece of semiconductor material with a p–n junction connected to two electrical terminals. Semiconductor diodes were the first semiconductor electronic devices. The discovery of asymmetric electrical conduction across the contact between a crystalline mineral and a metal was made by German physicist Ferdinand Braun in 1874. Today, most diodes are made of silicon, but other materials such as gallium arsenide and germanium are used.

Main functions:

     

                  The most common function of a diode is to allow an electric current to pass in one direction (called the diode's forward direction) while blocking it in the opposite direction (the reverse direction). As such, the diode can be viewed as an electronic version of a check valve. This unidirectional behavior is called rectification and is used to convert alternating current (ac) to direct current (dc). Forms of rectifiers, diodes can be used for such tasks as extracting modulation from radio signals in radio receivers.

  

History: 

     Thermionic (vacuum-tube) diodes and solid-state (semiconductor) diodes were developed separately, at approximately the same time, in the early 1900s, as radio receiver detectors. Until the 1950s, vacuum diodes were used more frequently in radios because the early point-contact semiconductor diodes were less stable. In addition, most receiving sets had vacuum tubes for amplification that could easily have the thermionic diodes included in the tube (for example the 12SQ7 double diode triode), and vacuum-tube rectifiers and gas-filled rectifiers were capable of handling some high-voltage/high-current rectification tasks better than the semiconductor diodes (such as selenium rectifiers) that were available at that time.

2.Railway Level-Crossing Gate Control through GSM

Similar to the above project, this is also a railway level-crossing gate control system, but it is implemented by using GSM technology. In this system, the railway level crossing gate is controlled by an SMS sent by the station master or the driver to the control area.

The system has a GSM modem interfaced with a control system. When a driver or station master sends an SMS ‘open’ to the GSM modem it receives that SMS and sends it to the microcontroller. The microcontroller acknowledges these signals and sends the command signals to the motor driver IC, which controls the direction of the motor for opening and closing the gate. Therefore, this IC sends a clockwise signal to the motor to open the gate and the status gets displayed on the LCD.


In the same way, to close the gate, another SMS needs to be sent to the microcontroller. Therefore, the motor driver drives the motor in anticlockwise direction after receiving the corresponding signals from the microcontroller.


These are the two projects based on the automatic railway gate control system for the operation of gate. There are many technologies that are available to achieve this operation including Zigbee, IR, etc. Apart from this, for any help regarding any projects, you can contact us by commenting in the comment section.

1. Railway Level-Crossing Gate Operation Remotely by an Android Device

Automatic railway gate control system is implemented to prevent accidents of the traction system at the railway crossing levels. Nowadays many accidents take place at the railway gate crossing due to uneven crossings, even when the gate is about to close. In general, a railway gate is normally operated by a gate keeper as he receives the information about the arrival of the train.

Railway safety is the most crucial aspect of railways all over the world. This is the cheapest mode of transportation all over the world, and therefore, accidents are bound to happen due to carelessness manual operations. Therefore, an automatic railway-crossing-gate controller is used to prevent accidents at unmanned level crossings to provide much needed safety. Such efficient controllers are mostly used in remote areas that often lack the services of a station master or line man at the crossing levels.

Automatic gate control system can be implemented using different technologies such as GSM, Bluetooth, and Android. This article describes two automatic railway gate control project topics involving Android