Wanted: Electrical genius

[71bigblock]

I want to maybe do some custom LED's for my truck.  I want to spell it out like this:

H
E
M
I

I want the whole thing lit up halfway, like when the head/parking lights are on.  When the brake is on, I want them fully lit up. 

Here's the tricky part.  When the signal is on, I would like them to be split.  Like

H
E

on one flash, and

M
I

on the other.  Is this possible?  I really want to do it, that would just make me so elated!  I'm sure its possible, but I need someone to tell me what I need, I can do the rest.  Thanks.   

[Bullitt-]

Something I've been saving....you would need two of these circuits I believe...No genius here tho
LED driven tail/brake Light Cluster



Constant current circuitry

12V Battery operation



Circuit diagram:



























Parts:

R1______________10K  1/4W Resistor
R2______________33R  1/4W Resistor (See Notes)
R3______________15R  1/4W Resistor (See Notes)

D1___________1N5819   40V 1A Schottky-barrier Diode (See Notes)
D2--D13________LEDs   High brightness, high efficiency red types (See Notes)

Q1____________BC547   45V 100mA NPN Transistor
Q2____________BC337   45V 800mA NPN Transistor

SW1____________SPST   Tail Light Switch
SW2____________SPST   Brake Light Switch



Comments:

This circuit was designed on request to drive a Light-cluster formed by several LEDs that can be mounted in the vehicle as a tail and brake light.
When SW1 is on, the cluster will illuminate at medium brightness. When brakes are operated, SW2 will be closed and the cluster will shine at maximum brightness.
These two brightness levels of the cluster are obtained by a constant current source drive formed by Q1 and Q2. The two constant current levels are set by R2 and R3 values.

Notes:

The cluster can be formed by up to 12 LEDs as shown in the circuit diagram. Common cluster types usually range from 5 to 10 LEDs.
Using the values shown above, stand-by current was 1mA; SW1 on = 20mA, SW2 on = 60mA.
Constant output current value can be changed by varying R2 and/or R3.
The formula is: R = 0.6/I (in Amperes).
Please note that the brake current is obtained by paralleling R2 and R3 values.
Use high brightness, high efficiency red LED types of suitable size and change R2 and R3 values to suit LED's Absolute Maximum Ratings.
Any Schottky-barrier type diode can be used in place of the 1N5819: the BAT46 type will be a very good choice.

[ntstlgl1970]

Once you figure out what you want to do, buying from places like digikey will save you some cash over buying at radio shack or some place like that.
Also they use lots of universal LED stuff on street rods, 1 and 2 rows wide for brake lights and so on that could help keep assembly time down (if you don't want to make your own breadboards). To make the letters flash alternate, you could use electrical feedback on the headlamp circuit to wig wag the pairs with the headlamps on (like newer cars where the parking lamps and side markers alternate with the turn signals on)

[71bigblock]

Hey thanks guys.

ntstlgl, I know that the some of the LX cars had that.  And I also know that guys that didnt have it on their chargers did a simple mod to make it do that. 

http://www.lxforums.com/board/showthread.php?t=32475&highlight=blinker

But it seems to only alternate when the head/parking lights are on, wierd...

You lost me at "electrical feedback" 

[ViperMan]

Why are the transistors necessary?  I think their purpose is to flash the LED's rapidly - faster than the eye can see - this allows higher amperage, and more brightness, without burning out the LED's.

You're probably going to need a decent number of LED's to do this, and I don't know that brightness will be a concern.  You can simply use two resistors - isolated from each other by diodes - to limit current differently with each switch.

I didn't see "electrical feedback" in the first reply...

Jeff

[ntstlgl1970]

The "electrical feedback" thing is using the headlamp circuit as an alternate ground for the side marker/turn signal circuit. I'll have to find my stuff from school to draw a diagram. Essentially, like when you see a car with one dim headlamp, you provide an alternate path to ground to induce a feedback loop with enough power to light the side marker alternately from the turn signal.

[ViperMan]

I think I understand, but what does a dim headlamp have to do with alternating turn-signal bulbs?

71 - I re-read the original post, and I'm stumped.  First, are these going in the tailights, or is this going to be a high-mount kind of thing?  So you want it like this:

(let's pretend lowercase means not as bright, caps means brightest)
ParkingLamps - reads "hemi"
Brake lights, reads "HEMI"
Turnsignals, alternates "heMI" and "HEmi" with each blink...

I think you're going to need a microprocessor to do this for each light, only because the turnsignal is either going to let all of it or half of it blink brighter, not alternating.  Also, how do you plan on controlling brightness?  Do you want only half the LED's to light, or do you want them to have less resistance and thus be brighter?

Jeff

[71bigblock]

Thanks guys.  Told you I needed some geniuses, lol.  A diagram would help sooooo much.  I'm a visual kinda guy...

Jeff, you have it right.  I do want them in the taillight.  But, I took an LED flashlight with brand new batteries and put it behind the lense to see how well it lit up, and, well, it wasnt spectacular.  I dont know how well you would be able to see the brake lights during the day. 

I have no idea how to do this LED stuff.  I signed up for the class that covered this in High School, but there werent enough kids signed up.  Sure enough, the next semester there were enough, but they didnt tell me that.   

[GoodysGotaCuda]

I tried to mess with LEDs, too involved for me! I couldn't sit there and just solder for hours!