Need some help designing a new LED taillight setup

[cg8798]

Ok so I created an LED taillight setup for my old car. I sold the car and sold my lights. I want to make them for my new car. But I face problems that I don't know how to tackle. For this car the lights will be running lights, brake lights, and turn signals. Now I've reviewed my cars schematics for the rear lights and know the wires for each. My issue lies in designing and wiring the new lights. Now I will use a PWM setup to control the brightness when braking but I want to make the turn signals sequential. I have a schematic from another forum I'm on that looks like this:
**broken link removed**
**broken link removed**
This is another picture of what they look like^
I don't understand this schematic but it is what he used to make them sequential. If anyone could explain it I would appreciate it.

I want to know how to make the signals sequential and run the brakes and the running lights. Can anyone help me out? Is it even possible to do run the lights this way?

 

[Andy1845c]

How many wires run to the taillights? I would assume just 2? Or are the turn signals and brake lights seperate? Is there a 3rd brake light or somthing that only lights when the brakes are applied? Your going to need to make sure when you step on the brake the lights go solid red, not both going sequential, right and left. Also keep in mind that the turn signal still needs to flash when the brake lights are on. This isn't so bad if you have a car with seperate lights, but if two red lights acts as stop/turn/tail your going to need some logic circuit or a micro controller to make sure the lights light properly.

The circiut you posted is just a 555 timer creating pulses and a 4017 Decade Counter that lights the leds one at a time. Its a pretty basic circuit. It will not do any more then the sequential part of what you want to do.

 

[ericgibbs]

The circiut you posted is just a 555 timer creating pulses and a 4017 Decade Counter that lights the leds one at a time. Its a pretty basic circuit. It will not do any more then the sequential part of what you want to do.

hi Andy,
It looks a though the components T1 thru T7 are SCR's, so the lights will be a 'bar' display, lighting one LED in sequence.
I think the +12V to the Vreg is from the brake pedal switch, which when not pressed removes the power to the SCR's so they can switch off.

 

[Andy1845c]

hi Andy,
It looks a though the components T1 thru T7 are SCR's, so the lights will be a 'bar' display, lighting one LED in sequence.

Why yes they are SCRs...... Thanks for pointing that out, Eric. I completly missed that......

So now that I am also a bit confused, for my sake and the OP's sake,

IC3 is a power regulator. Its powers the 555 and 4017 that is hooked to the gates on the SCRs, along with whatever is on the other side of the SCRs (LEDs we assume).

So 12v+ must get hooked into the single wire you likley have for your turn/stop lights. When the turn signal is on, each pulse created by the mechanical turn signal flasher starts up the 555 and latches the SCRs one by one until the light is fully on, then when the mechanical flasher releases, everything powers off and the SCRs can reset. This cycle repetes as long as the turn signal is on.

When you hit the brakes, both left and right side will light one LED at a time until all of the SCRs are latched and they will hold steady on until the brake is released and the SCRs can reset.

Is that accurate, Eric?

If so this takes care of what I mentioned earlier about seperating the brake and turn functions.

 

[ericgibbs]

:

When you hit the brakes, both left and right side will light one LED at a time until all of the SCRs are latched and they will hold steady on until the brake is released and the SCRs can reset.

Is that accurate, Eric?

If so this takes care of what I mentioned earlier about seperating the brake and turn functions.

hi Andy,
That description sounds right to me.

Personally, I like my car braking lights to come on 'full' when I hit the brake.

I dont want the truck driver behind thinking 'is that brake light on or not', leaving to late to brake.

 

[Andy1845c]

hi Andy,
That description sounds right to me.

Personally, I like my car braking lights to come on 'full' when I hit the brake.

I agree. I would actually question the legality of using this circuit in the USA. The OP didn't fill in his location, but in America I think you could face a lawsuit if someone was injured rear-ending you and you were found to have a goofy circuit controling critical vehicle lights.

 

[SMUGangsta]

not sure how the law is in the US, but in the UK we are prohibited from anything but a STABLE full on brake light. Even though research 'suggests' that flashing brake lights (giving around 5 flashes before remaining steady) lead to faster reaction times from the driver behind - they are still ilegal here.

just my $0.02

 

[Andy1845c]

Even though research 'suggests' that flashing brake lights (giving around 5 flashes before remaining steady) lead to faster reaction times from the driver behind - they are still ilegal here.

just my $0.02

I have seen some of these flashing brake lights on big trucks around here. I was going to add some to a trailer I have, but I couldn't find any reliable info on if they are legal here or not. I agree they are eye catching, but i'm not sure they would be if everyone had them.

 

[SMUGangsta]

apparently the human brain is wired to notice flashing things. I am building a Kit Car at the moment, well its just a Fibreglass shell - everything else needs made to fit - anyway I wanted to be a bit creative and add flashing brakelights and 'running' indicators to name a few of the lighting enhancements I wanted - but after downloading the vehicle construction and use regulations (lighting) and it strictly forbids both

 

[cg8798]

ok guys let me clarify things here.

the system the guy is using that I grabbed that schematic from is for his turn signals only. This is what he says: "coupled with an SCR on each array, the array will "Build" until the end and when power is removed, the array will reset." So for the signals the setup just builds power across all his led arrays and then resests and starts again.

Now I wanted to take this idea and put it into my new tails. My car now is two seperate bays for brakes/signals. They both light up with running and brakes, but the signal is in its own bay. Its a 99 galant. So I don't know if that makes a difference. I intended that for each side I would build a pwm. Pwm would be connected to the running, brake, and signal lights. So the pwm would control the brightness when the brakes were applied but still would cut power in/out when the signal was active. The only thing I wanted was when the signal was active to make the high brightness of the brakes activate sequentially. Does that make sense? I am in CT so yeah in america. Just like many us cars that have the blinker turn off even when the brakes are active. The rest of them would still be on, but the signal would just make the brightness sequentially go across the taillight for the blinker....possible?

 

[Andy1845c]

Anything is possible, just depends on your skill level and budget.

So, if i understand, you want to make the brakes lights work normally and only have sequential turn signals?

I would set the PWM part aside for the moment and get the brake and signals figured out. The running lights could always be seperate LEDs to make things easier.

 

[Willbe]

Personally, I like my car braking lights to come on 'full' when I hit the brake.

I dont want the truck driver behind thinking 'is that brake light on or not', leaving to late to brake.

It's probably illegal in the U.S. for the brake lights not to come on ASAP. Using LEDs over incandescents might shave 100 mS off peoples' response times.

 

[cg8798]

I rethought the idea and I think I'm doing something different. So instead of making all the leds a sequential setup even with brakes, I'm going to design them as the top lines will always be bright for brakes. The bottom lines will be bright on brakes but be the sequential signals. So this way the top will still be bright but never go away when braking. Should be a safer setup. Just still need help figuring out how the 4017 decade counter works with the setup above.

I need the setup to be like his because it allows him to light all of the leds up. Usually the chip only lights up one led at a time. He has it so the light up one at a time but stay lit. How did he do that? Here is a link to the video so you can see what I mean: YouTube - N14 Pulsar with Seq Turns Daytime video

Two more things
1. this is his PWM setup as well. Is this the left side of the schematic I posted above?
**broken link removed**

2. this is the electronic flasher he uses to correct the hyper flashing. Anyone seen this before?
**broken link removed**

 

[cg8798]

Ok so I've rethought the idea. My new idea is to make me design with two extra rows on the bottom. All the lines will act as the running and brakes. But only the bottom two lines will act as the sequential signals. I like the idea better. Now I'm getting overwhelmed looking at schematics and how stuff works. I should start from the beginning but don't know where that is.

Now what I've been reading I find that the setup goes like this: pwm -> sharp voltage regulator -> 4017 diagram i posted above. Below is the diagram of the pwm setup used on a similar project.
**broken link removed**

I assume that the PQ12RF21 on both diagrams are the same. Which means that the power goes through the pwm, the output from the pwm goes to a sharp pq12rf21, then the output from the regulator goes to the 555 timer and the 4017 chip. Is that correct?

I want to use the same setup on both sides to make sure that each side is regulated and safe. Thing is that I don't understand the full point of the voltage regulator. What is its purpose? From what I figure the SCR is what will keep the leds lit when the 4017 goes through its sequence. When the sequence stops it will reset the SCR and all the leds turn off until the sequence passes over each SCR again. Right?

I have a lot of diagrams but I dont want to post them all. Unfortunately I am a visual learner. I need to see it and hear it to understand. The diagrams I see are helpful but I don't understand them fully.

I also do not know what all the small writing is on the schematics. I realize they are resistors and diodes and such but I can't read the whole thing. Can anyone help me out with that?

 

[Andy1845c]

Now what I've been reading I find that the setup goes like this: pwm -> sharp voltage regulator -> 4017 diagram i posted above. Below is the diagram of the pwm setup used on a similar project.

Not quite sure I follow what your saying. You can't PWM a regulator or a 555 timer/4017. You can only use the PWM on the LEDs in this circuit.

I assume that the PQ12RF21 on both diagrams are the same. Which means that the power goes through the pwm, the output from the pwm goes to a sharp pq12rf21, then the output from the regulator goes to the 555 timer and the 4017 chip. Is that correct?

I don't think so. They appear to be seperate circuits to me. Are they used together where you found them?

I want to use the same setup on both sides to make sure that each side is regulated and safe. Thing is that I don't understand the full point of the voltage regulator. What is its purpose? From what I figure the SCR is what will keep the leds lit when the 4017 goes through its sequence. When the sequence stops it will reset the SCR and all the leds turn off until the sequence passes over each SCR again. Right?

The regulator keeps the voltage stable, and at a preset value. The sequence from the 4017 can only turn ON the SCRs, or latch them. To make them stop conducting, the voltage though them must be cut off. So in this case the power to the requlator is cut off.

I also do not know what all the small writing is on the schematics. I realize they are resistors and diodes and such but I can't read the whole thing. Can anyone help me out with that?

What part can't you read? The components are labled and resistor and capacitor values are given. I don't really see anything else. Let us know what part you can't make sense of.


Question for other members - What does that TRIG terminal do on that regulator? I pulled up the datasheet for it and it calls it an ON/OFF on one version and a output adjustment on another version on the same sheet. I've never used a regulator like that before.

 

[cg8798]

I am just not familiar with reading schematics. I do understand it now. I looked and went back to knowledge from building a pwm before. I'm just confused on if the regulator in each schematic is the same one. Meaning the system is connected. Maybe not. If anyone can read them together and figure out what goes where is what I need help with.

To start this off, is my idea possible? Is it possible to makes all the leds light up as brakes but then make only the bottom rows stop and sequentially light when the blinker is on? Can it be wired that way?

I think the trig is if you're using a switch to turn it on and off.

 

[cg8798]

This is the thread I have been going off of for the sequential stuff. I can't post the link cause you need to be a member to access it so here:

For the PWM, i made my own design for the circuit board, based heavily on the research from azdave and DarkAngel. This design has been layed out for my specific setup, but should anyone like to use it, i'm sure it will work just fine. The PWM is based off the Quickar PWM that has been posted in many threads. Using the famous Sharp PQ12RD21 for each array.

All LED Arrays in the car are regulated to either 9v or 12v using the Sharp Regulators. (PQ09RD21 and PQ12RD21).


Schematic the PWM: Please not this design leaves the timing circuit un-regulated.
**broken link removed**
**broken link removed**

Sequential turn signals

Again, azdave has his hand in the pie with guidence for references for a base circuit, and coupled with an SCR on each array, the array will "Build" until the end and when power is removed, the array will reset.

I have chosen to use only 7 of the 10 outputs from the 4017 chip as i have 14x4 rows of led's, 2 rows lit per segment. It flows quite nicely.

Again the circuit and layout has been made specificaly for my use, but should be able to be adapted for any situation. I decided to use the 10pin IDC header as a means for easy and fool-proof connection to the sequential array, should the board everneed to be changed or if the array needs to be converted to flash all at once, a simple pinout converter can be used to do that instead of having to dis-assemble the lights or do any wire cutting.

Schematic for the Sequential Turn Signal Array: T1-7 are 2N5062 SCR's
**broken link removed**
**broken link removed**

 

[Andy1845c]

I need the setup to be like his because it allows him to light all of the leds up. Usually the chip only lights up one led at a time. He has it so the light up one at a time but stay lit. How did he do that? Here is a link to the video so you can see what I mean: YouTube - N14 Pulsar with Seq Turns Daytime video

The SCRs in the circuit you posted will keep the leds lit until the flasher turns off power to everything. The circuit you posted should work just like the video.

I don't think the 2 circuits are drawn to use the same regulator. You could re-draw it to use just one, but theres really not alot of point in that. Regulators are pretty cheap, plus they can only handle so much current and heat, so its not a bad idea to split up the load.

The PWM circuit will give you 2 levels of brightness as you already know, the other will make your signal look like the video you posted.

This would all be pretty easy if you had signals like the guy in the video. Orange lights that are only used as blinkers and red lights that are just brake and running lights.

Things get more complex if you need one light, or part of one light, to somtimes be a brake light, somtimes a running light and somtimes a signal.

You can easily hook up the part of the lights that are only running/brake to the PWM circuit, and you can hook the turn signal circuit to the leds you want to be signals. But now your at a stop light waiting to turn left and your foot is on the brake and your left signal is on, you need the right side and part of the left side to be all brake light and the signal part of the left side to still be a signal. You can easily override the signals to make everything all brake lights, but you still need signals when your braking and thats where this is going to get more complicated. There is certinly a way to get it done, but I can't offer a good solution at the moment.

Possibly a more experianced member here can offer a simple logic solution or possibly there is a circuit you could find using google or by searching here that would provide some insparation.

 

[cg8798]

ok thanks. I know there is a way too I just dont have the knowledge to figure it out now. My thought was that the power for the running/brake lights would be on, but when the signal was turned on the power would reroute through the 555 and 4017 to become sequential. There is a guy on another forum who did something similar and I know he could help me but he hasn't replied in my thread. I'm not getting much of anything in the forum and its frustrating because I know they can help me figure it out.

quesiton....can a tristate buffer gate work for this? I'm trying to read up on this stuff and found that a tristate buffer gate has three outputs; high, low, floating, and are activated by an enable. Does that mean it could be wired to control the low running light, high brakes, and the floating signals? Or is that way off? I'm just learning now.

 

[Andy1845c]

I can't answer the tri-state buffer question. I was trying to think if an XOR gate could be used, but am am not familiar enough with logic circuits. I was kinda hoping some other member would chime in on this one.