dear sir , i need a project design for railway led signalling light . The
light must have 4 modes. 1) red stable 2) green stable 3) red flashes 4)
green flashes also suggest suitable charges for the circuit.
The proposed railway signal lamp circuit using flashing LEDs can be implemented through a simple IC 555 astable circuit as shown below:
Referring to the above diagram, the circuit may be understood as explained below:
The IC 555 is configured in its standard astable mode which is supposed to generate alternate ON/OFF potential at its pin#3.
The IC is capable and is rated to deliver up to around 200mA current, therefore 1 watt LEDs become suitable for working directly with this pinout of the IC.
Since the 1 watt LEDs are rated to handle 350mA, the available lower amount of current allows the LEDs to work without heatsinks, yet so, with 100mA current the light from these LEDs can be expected to be significantly bright and quite applicable for the requested railway safety signal lamp application.
The 1M pot is used to adjust the flashing rate on the LEDs, while the switches determine the LED operational modes as per the requested specs.
The switches must be SPDT type with CENTER OFF facility.
Toggling the relevant switches downwards produces a constant switched ON response on the LEDs, while toggling them on the lower side allows the LEDs to flash.
The center OFF feature of the switch can be used for keeping the LEDs shut off.
The LEDs must be housed inside high gloss reflector cones for getting an enhanced light output and an increased visibility range.