Help with designing an efficient LED circuit

[7slaterj]

Hey guys,
I'm currently designing a small project for a university module.
The theory is to have a light on top of a bus stop which signals to a bus driver that a pedestrian wants the bus.
I'm having a bit of a problem with designing the circuit as I'm pretty useless once it comes to ACDC stuff. (mechanical engineer)

-The light will be operated by a button, and is active when the button is held down.
-It must be a green LED light (dunno how many or which one :s)
-LED will be placed on top of the shelter or bus stop pole thingy.
-Must be energy efficient !!!
-cost effective, safe etc etc

Any suggestions would be really helpful. I wouldnt mind a small explanation to with it though haha.
If i do become rich from this, I'll give you 10% of my profits haha !!

Thanks for your time and regards,
Jonathan

 

[malcolmsanford]

So if the light is going to be on when a button is held down, does that mean the passenger has to stand there with their fingers depressing the button all the time, or at least until a) they see the bus and b) until the bus arrives .............sort of a bit of a pain really and highly unlikely to happen.
It would mean the passenger having his/her eyes glued to the road waiting to see the bus, because if they missed it's approach the bus would sail by .....

Bit more thinking over really

 

[Spoon]

Wouldnt a sensor that detects a person standing by the bus stop be better than a push button?
The bus stop near us has 4 different numbered busses taking different routes. How would you get round this with just one light, unless there is only the single bus route from the bus stop?

 

[Silly Sausage]

I just stick my arm out.





It's just a daft scenario for a simple project.
In my 2nd year, we were split up into groups to design a hand drying device for a toilet. One group came up with a towel rail with a towel on it...simple!

To OP, you need a DC supply and a resistor in series with the LED. You'll have to look at the LED spec to calculate the resistor value.

 

[7slaterj]

Yeh, just a simple project.
Its mainly to stop people sticking there arm out lol. If it was a switch people would just leave it on. If you can stick your hand out in the road, then you can simply press a button. I know pressing a button is hard work for some people, but its the only way here. haha
And a sensor would be pretty stupid. The button is pressed just like when you press the "stop the bus" button when your actually on the bus. Its just a signal for the driver that somebody wants his bus lol. A sensor would be on all the time.

Anyhow haha thanks for the replys

Any chance of getting a schematic from one of you guys ??
Thanks gain

 

[7slaterj]

Oh and is there anyway round using a resistor ?? Its just to make it more efficient.
And is it possible to have a rechargeable battery which is hooked up to some sort of mains ?? :s

 

[Brightspark2]

Oh and is there anyway round using a resistor ?? Its just to make it more efficient.
And is it possible to have a rechargeable battery which is hooked up to some sort of mains ?? :s

Solar power?? or similiar??....

 

[Adam W]

Maybe something along the lines of push a button which illuminates an LED sign on top of the bus stop, or even in the cab of the bus by radio signal, held on with a hold-up coil with a light by the button so the passenger knows it's been activated. Then when the bus comes into close proximity with the bus stop the signal resets. This could be done by radio signal, bluetooth or even just a reset button in the cab of the bus.

Alternatively a capacitive proximity switch which triggers whenever someone is standing by the bus stop for whatever reason, which activates a device in the road which automatically slams on the brakes of whichever bus passes over the top of it whether it is in service or not.

If there were such a device I'd probably still try to make eye contact with the bus driver in case they haven't seen the fancy light on the bus stop or in case it isn't working - chances are if the bus driver sees nobody standing at the bus stop they'll assume the button has been pressed in error and not stop anyway. If I was supposed to press a button I'd press it as well in case the bus driver decides to be a real jobsworth about it.

 

[Guitarist]

I would have the button latch a relay on for say 2 minutes. That way the passenger can see the bus approaching, press the button and and the light will stay on for said amount of time. Wouldn't want it so you have to keep your finger on the button.

 

[Des 56]

You just as well design a prosthetic arm that the would be passenger can lever out to attract the drivers attention
It could even have a glowing red thumb on the end

If he's a notorious "wont stop" driver,the arm can be moved sideways in a waving direction with the glowing red thumb replaced with two fingers in a V formation