help on school project diode and lamp

[jfj]

hi, my teacher has set me this project which seems really simple but I'm not sure there isnt a trap.
He wants me to makea circuit which lights a diode when its working. so for example when you turn your car headlights on, this diode should come on,but if the bulb is blown, then the diode doesnt come on.
i had thought of putting the diode and bulb in series but there's not enough current and now i'm thinking of using a relay to light the led circuit but im worried that current going through the control circuit will be too much.
Does anyone have a simple solution to this
help

 

[ericgibbs]

hi, my teacher has set me this project which seems really simple but I'm not sure there isnt a trap.
He wants me to makea circuit which lights a diode when its working. so for example when you turn your car headlights on, this diode should come on,but if the bulb is blown, then the diode doesnt come on.
i had thought of putting the diode and bulb in series but there's not enough current and now i'm thinking of using a relay to light the led circuit but im worried that current going through the control circuit will be too much.
Does anyone have a simple solution to this
help

hi,
If this for a school demonstration and not a 'real' car headlight you could use a small lamp.
eg: say you have a 9V battery , a RED led [which has a voltage drop of about 2V], use a 6V cycle lamp bulb that requires less than 25mA current.
Connect the LED and lamp in series.

Do you follow.?

Look at this chart to select the best LED colour

 

[jfj]

thanks eric,
to be honest its for my son school project here in france.........and my electronic knowledge is kinda basic so i cant help him as i would like to.
the example of the car headlights is what his teacher gave him, so i think that must be what he's looking for.
but i have no idea of how to go about this so any help would be greatly appreciated

 

[ericgibbs]

thanks eric,
to be honest its for my son school project here in france.........and my electronic knowledge is kinda basic so i cant help him as i would like to.
the example of the car headlights is what his teacher gave him, so i think that must be what he's looking for.
but i have no idea of how to go about this so any help would be greatly appreciated

hi Dad.
If its a real car lamp, say a sidelight 12V at about 6Watts, [thats about 0.5Amp] you
could use a series power resistor, transistor, resistor and LED for a demo.

I guess you need a circuit diagram.?

EDIT:
Look at this option, suitable for a demo.
NOTE:
If you plan to use a different wattage lamp the 2R resistor needs to be changed, let me know.

 

[jfj]

thanks eric,
its all completely beyond me; i'll pass it on and see what happens.......