traffic lights with white led lights instead of colored diy

let me start with that i know basically nothing, i thought it would be a good project for my dad and i to do. Anyway, i have been searching online for schematics for a traffic light controller. i have found plenty,But none of them have it with white leds( i have a full size traffic light with the colored lenses. so i only need white leds) also i have found that there are different schematics for white and colored leds. so i am looking for some help for a schematic and a parts list. if anyone can help in laymans terms that would be greatly appreciated

 

[Michael A. Terrell]

bigrdjimmy@gmail.com wrote:

let me start with that i know basically nothing, i thought it would be a good project for my dad and i to do. Anyway, i have been searching online for schematics for a traffic light controller. i have found plenty,But none of them have it with white leds( i have a full size traffic light with the colored lenses. so i only need white leds) also i have found that there are different schematics for white and colored leds. so i am looking for some help for a schematic and a parts list. if anyone can help in laymans terms that would be greatly appreciated

They use colored LEDs for better efficiency. Why use white LEDs,
then waste the light in the filters?

 

On Thursday, October 18, 2012 8:42:05 PM UTC-4, Michael Terrell wrote:

bigrdjimmy@gmail.com wrote:



let me start with that i know basically nothing, i thought it would be a good project for my dad and i to do. Anyway, i have been searching online for schematics for a traffic light controller. i have found plenty,But none of them have it with white leds( i have a full size traffic light with the colored lenses. so i only need white leds) also i have found that there are different schematics for white and colored leds. so i am looking for some help for a schematic and a parts list. if anyone can help in laymans terms that would be greatly appreciated





They use colored LEDs for better efficiency. Why use white LEDs,

then waste the light in the filters?

i fear the colors will get lost and not be as bright

 

On Thursday, October 18, 2012 8:39:13 PM UTC-4, bigrd...@gmail.com wrote:

let me start with that i know basically nothing, i thought it would be a good project for my dad and i to do. Anyway, i have been searching online for schematics for a traffic light controller. i have found plenty,But none of them have it with white leds( i have a full size traffic light with the colored lenses. so i only need white leds) also i have found that there are different schematics for white and colored leds. so i am looking for some help for a schematic and a parts list. if anyone can help in laymans terms that would be greatly appreciated

also i think i should be using about 5 leds per color, i hope it will be bright enough

 

[krw@att.bizzzzzzzzzzzz]

On Thu, 18 Oct 2012 17:44:17 -0700 (PDT), bigrdjimmy@gmail.com wrote:

On Thursday, October 18, 2012 8:42:05 PM UTC-4, Michael Terrell wrote:
bigrdjimmy@gmail.com wrote:



let me start with that i know basically nothing, i thought it would be a good project for my dad and i to do. Anyway, i have been searching online for schematics for a traffic light controller. i have found plenty,But none of them have it with white leds( i have a full size traffic light with the colored lenses. so i only need white leds) also i have found that there are different schematics for white and colored leds. so i am looking for some help for a schematic and a parts list. if anyone can help in laymans terms that would be greatly appreciated





They use colored LEDs for better efficiency. Why use white LEDs,

then waste the light in the filters?

i fear the colors will get lost and not be as bright

Colored LEDs will be brighter for the energy used because you won't be losing
(as much) energy in the filters. The appropriate color LEDs really is the way
to go. Greens, especially, can be very efficient (bright).

 

[Tim Wescott]

On Thu, 18 Oct 2012 17:44:17 -0700, bigrdjimmy wrote:

On Thursday, October 18, 2012 8:42:05 PM UTC-4, Michael Terrell wrote:
bigrdjimmy@gmail.com wrote:



let me start with that i know basically nothing, i thought it would
be a good project for my dad and i to do. Anyway, i have been
searching online for schematics for a traffic light controller. i
have found plenty,But none of them have it with white leds( i have a
full size traffic light with the colored lenses. so i only need white
leds) also i have found that there are different schematics for white
and colored leds. so i am looking for some help for a schematic and a
parts list. if anyone can help in laymans terms that would be greatly
appreciated





They use colored LEDs for better efficiency. Why use white LEDs,

then waste the light in the filters?

i fear the colors will get lost and not be as bright

LED's don't lose colors.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

 

[o pere o]

On 10/19/2012 02:39 AM, bigrdjimmy@gmail.com wrote:

let me start with that i know basically nothing, i thought it would
be a good project for my dad and i to do. Anyway, i have been

searching online for schematics for a traffic light controller.
i have found plenty,But none of them have it with white leds( i
have a full size traffic light with the colored lenses. so i only
need white leds) also i have found that there are different schematics
for white and colored leds. so i am looking for some help for a
schematic and a parts list. if anyone can help in laymans terms that
would be greatly appreciated
I would start with any schematic you found, that is, with colored LEDS.
(I have found this: http://lumberjocks.com/souichiro/blog/21142 which
may not be the one you found, but it won't matter)

To drive white LEDs you just have to tweak the limiting resistors
(R4..R6 in the link). To be safe, begin with the biggest value in the
schematic (probably the red one) and decrease the resistance until it
looks bright enough (or the ammeter connected in series with one LED
gives the value stated in the LED's datasheet).

Pere

 

[krw@att.bizzzzzzzzzzzz]

On Fri, 19 Oct 2012 13:50:34 +0200, o pere o <me@somewhere.net> wrote:

On 10/19/2012 02:39 AM, bigrdjimmy@gmail.com wrote:
let me start with that i know basically nothing, i thought it would
be a good project for my dad and i to do. Anyway, i have been
searching online for schematics for a traffic light controller.
i have found plenty,But none of them have it with white leds( i
have a full size traffic light with the colored lenses. so i only
need white leds) also i have found that there are different schematics
for white and colored leds. so i am looking for some help for a
schematic and a parts list. if anyone can help in laymans terms that
would be greatly appreciated


I would start with any schematic you found, that is, with colored LEDS.
(I have found this: http://lumberjocks.com/souichiro/blog/21142 which
may not be the one you found, but it won't matter)

To drive white LEDs you just have to tweak the limiting resistors
(R4..R6 in the link). To be safe, begin with the biggest value in the
schematic (probably the red one) and decrease the resistance until it
looks bright enough (or the ammeter connected in series with one LED
gives the value stated in the LED's datasheet).

You already have a shunt resistor built into the circuit. Just measure the
voltage across it and divide by its resistance to find the LED current.

 

[o pere o]

On 10/19/2012 02:48 PM, krw@att.bizzzzzzzzzzzz wrote:

On Fri, 19 Oct 2012 13:50:34 +0200, o pere o <me@somewhere.net> wrote:

On 10/19/2012 02:39 AM, bigrdjimmy@gmail.com wrote:
let me start with that i know basically nothing, i thought it would
be a good project for my dad and i to do. Anyway, i have been
searching online for schematics for a traffic light controller.
i have found plenty,But none of them have it with white leds( i
have a full size traffic light with the colored lenses. so i only
need white leds) also i have found that there are different schematics
for white and colored leds. so i am looking for some help for a
schematic and a parts list. if anyone can help in laymans terms that
would be greatly appreciated


I would start with any schematic you found, that is, with colored LEDS.
(I have found this: http://lumberjocks.com/souichiro/blog/21142 which
may not be the one you found, but it won't matter)

To drive white LEDs you just have to tweak the limiting resistors
(R4..R6 in the link). To be safe, begin with the biggest value in the
schematic (probably the red one) and decrease the resistance until it
looks bright enough (or the ammeter connected in series with one LED
gives the value stated in the LED's datasheet).

You already have a shunt resistor built into the circuit. Just measure the
voltage across it and divide by its resistance to find the LED current.

Absolutely true !

 

On Thu, 18 Oct 2012 17:41:29 -0700 (PDT), bigrdjimmy@gmail.com wrote:

On Thursday, October 18, 2012 8:39:13 PM UTC-4, bigrd...@gmail.com wrote:
let me start with that i know basically nothing, i thought it would be a good project for my dad and i to do. Anyway, i have been searching online for schematics for a traffic light controller. i have found plenty,But none of them have it with white leds( i have a full size traffic light with the colored lenses. so i only need white leds) also i have found that there are different schematics for white and colored leds. so i am looking for some help for a schematic and a parts list. if anyone can help in laymans terms that would be greatly appreciated

also i think i should be using about 5 leds per color, i hope it will be bright enough

Bright enough for what? Model train layout or real life traffic?

And what are the reliability requirements - leds may last "100,000
hours) gradually dimming.. but in a series connected string one
failure may take out the string or shorten its life.

White leds are not a good choice since the phosphors used only fool
our eyes into seeing white light - if you look at a spectrum of the
light you see which bands are emphasized.

BTW a CD can be used as a diffraction grating (like a prism but
different) to break out the bands so you can see what colors are
there.

The reason for using colored LEDs is because the efficiency in their
primary color is often higher than using white and losing all the
colors you don't want through filters. Not to say that there aren't
lots of aqua, green, pink, etc LEDs that use specialized phosphors to
only emit one color (to our eyes anyway) that may be good choices.

 

[ehsjr]

On 10/19/2012 7:50 AM, o pere o wrote:

On 10/19/2012 02:39 AM, bigrdjimmy@gmail.com wrote:
let me start with that i know basically nothing, i thought it would
be a good project for my dad and i to do. Anyway, i have been
searching online for schematics for a traffic light controller.
i have found plenty,But none of them have it with white leds( i
have a full size traffic light with the colored lenses. so i only
need white leds) also i have found that there are different schematics
for white and colored leds. so i am looking for some help for a
schematic and a parts list. if anyone can help in laymans terms that
would be greatly appreciated


I would start with any schematic you found, that is, with colored LEDS.
(I have found this: http://lumberjocks.com/souichiro/blog/21142 which
may not be the one you found, but it won't matter)

Nice starting place. To the op: With the one at that url,
you could move D4 to base of T1, & D6 to base of T3 to get longer
green & red on times, and shorter yellow on time. As drawn, it
gives equal on times for all three colors.

Ed

To drive white LEDs you just have to tweak the limiting resistors
(R4..R6 in the link). To be safe, begin with the biggest value in the
schematic (probably the red one) and decrease the resistance until it
looks bright enough (or the ammeter connected in series with one LED
gives the value stated in the LED's datasheet).

Pere