Railway gate control system

[arpita]

hi!!
I m in 2 yr(electronics). i was studying the project on "automatic railway gate control system".i couldnt understand wat causes the ir led to glow which further is sensed by the sensor n then it activates the controller...m i rightly interpreting???i have given the the site frm where i had studied the project...can anyone plz explain it...

**broken link removed**

 

[donniedj]

The railway link is shocking to me. All this time I thought train gates and indicators were already automated. Is it actually true that this process is still manual? A guy has to go and push a button as a train appoaches a crossing and must be actually told by the train driver "I am approaching"? Seems beyond reason to me, I don't know.

Take a look at a IR-Module datasheet:
**broken link removed**

Starting simple. Try to understand line of sight light detection or interruption. The light receiver will put out relatively constant voltage level given the light source is constant. When the light beam is interrupted, the receiver responds by changing its output voltage level. Change can be either increase or descrease in voltage, the change is whats important. So then the 8051 detects the change and does its job.

On to specifics. Visible light detectors do not function properly in a visible light environment. So Infra-red light is employed for its low ambient level to transmission level ratio. This same railway gate control could use constant IR transmission without need of the 555 timer. So why use pulsating IR? Pulsating IR can be filtered, which gives the advantage of suppressing false interrupts like naturally varying ambient light levels. IR-Receiver modules are good for suppressing false transient interruptions and they auto adjust to changes in ambient light. The IR-Emitter is driven by a 555 at 38KHZ to satisfy the 38KHZ requirement of the IR-Receiver module. This 8051 design is taking advantage of the suppression feature of the IR-module. It will reject a constant 38KHZ signal. So now when a train passes between the line of site sensors (emitter-to-receiver) that constant 38KHZ signal is momentarily interrupted. The interruption forces the IR-module to come out of rejection mode and sends a pulse to the 555 then 555 sends pulse to 8051 chip.

Brevity. The BC548 transistor cause the IR Led to glow. BC548 pulsates at 38KHZ because its base is driver by a 38KHZ generator, 555. The 555 timer signal is governed by its 10K, 10K, .001uF little buddies.

 

[kchriste]

Actually, most REAL railway gate controllers work on an inductive loop system. Wires are attached to both rails and as the train approaches, the wheels/axels complete the loop and a large inductor is formed which decreases in inductance as the train approaches. Control circuitry senses this varying inductance and the gate is triggered before the train is at the crossing.

 

[Nigel Goodwin]

The railway link is shocking to me. All this time I thought train gates and indicators were already automated. Is it actually true that this process is still manual? A guy has to go and push a button as a train appoaches a crossing and must be actually told by the train driver "I am approaching"? Seems beyond reason to me, I don't know.

If the OP had filled his location in?, you would have seen he's in India - where the British built the railway system back in Victorian times - somewhat before IR and inductive lops!

As far as I know it still runs much as it did back then?, and much more efficiently than the 'modern' UK rail system!!!.

 

[bunghole]

The railway link is shocking to me. All this time I thought train gates and indicators were already automated. Is it actually true that this process is still manual? A guy has to go and push a button as a train appoaches a crossing and must be actually told by the train driver "I am approaching"? Seems beyond reason to me, I don't know.

Take a look at a IR-Module datasheet:
**broken link removed**

Starting simple. Try to understand line of sight light detection or interruption. The light receiver will put out relatively constant voltage level given the light source is constant. When the light beam is interrupted, the receiver responds by changing its output voltage level. Change can be either increase or descrease in voltage, the change is whats important. So then the 8051 detects the change and does its job.

On to specifics. Visible light detectors do not function properly in a visible light environment. So Infra-red light is employed for its low ambient level to transmission level ratio. This same railway gate control could use constant IR transmission without need of the 555 timer. So why use pulsating IR? Pulsating IR can be filtered, which gives the advantage of suppressing false interrupts like naturally varying ambient light levels. IR-Receiver modules are good for suppressing false transient interruptions and they auto adjust to changes in ambient light. The IR-Emitter is driven by a 555 at 38KHZ to satisfy the 38KHZ requirement of the IR-Receiver module. This 8051 design is taking advantage of the suppression feature of the IR-module. It will reject a constant 38KHZ signal. So now when a train passes between the line of site sensors (emitter-to-receiver) that constant 38KHZ signal is momentarily interrupted. The interruption forces the IR-module to come out of rejection mode and sends a pulse to the 555 then 555 sends pulse to 8051 chip.

Brevity. The BC548 transistor cause the IR Led to glow. BC548 pulsates at 38KHZ because its base is driver by a 38KHZ generator, 555. The 555 timer signal is governed by its 10K, 10K, .001uF little buddies.

believe it or not, there is a manual level crossing still in use. when a train is approaching, a buzzer goes of in a sort of little house where the operator sits. he goes out and goes to swing the gates shut to traffic. Sandringham line, Down direction after Brighton Beach (Melbourne, Victoria, Australia).