Converting LED Turn Signals into Sequential Signals (Show Only)

Thread Starter

ACollins

Joined Feb 11, 2016
3
Hi all,

Before I begin, to mitigate replies about not altering exterior vehicle lighting, etc... This project is for show only and not intended for road use, no ordinances against it, not breaking any codes, all that jazz...
I have a show car with a set of aftermarket tail lights, and the turn signals consist of 16 LEDs arranged in an arrow in the direction of turn.
With the current arrangement they all blink simultaneously like a normal signal.
What I'm trying to do is to get them to stack/chase with each blink, i.e. LEDs go 1 - 1,2 - 1,2,3 - 1,2,3,4 - 1,2,3,4,5 [...] 1,...,16 then after a pause, repeat.
I found some ways to get them to sequence with a 555 timer and two 4017 ICs but I'm not sure how or whether they'd stack as well. Unfortunately my digital-electronics knowledge has all but faded away since school. I've seen a you-tube video with the same lights made to be sequential but the author hasn't responded to my inquiries about the setup.

Any help would be much appreciated.

Thanks.

-AC
 

crutschow

Joined Mar 14, 2008
24,397
The tricky part is doing the 16 different sequences in order.
Not sure there's an easy way to do that without a microprocessor to control everything.
 

Thread Starter

ACollins

Joined Feb 11, 2016
3
I've thought about getting some ARDUINO UNOs for it, but was hoping there could be a simpler/cheaper option since I'm really only looking for the one sequence.
 

Thread Starter

ACollins

Joined Feb 11, 2016
3
I'm not sure if this helps at all but this is what I'm looking to make, I'm a visual person so this makes more sense to me than trying to type it out.
Turn signals already have a relay to flash ON/OFF, so I'm looking to build a circuit that interrupts that signal to the LEDs and translates the ON pulse to:
o- - - - - - - - - - - - - - -
oo- - - - - - - - - - - - - -
ooo- - - - - - - - - - - - -
oooo- - - - - - - - - - - -
ooooo- - - - - - - - - - -
oooooo- - - - - - - - - -
ooooooo- - - - - - - - -
oooooooo- - - - - - - -
ooooooooo- - - - - - -
oooooooooo- - - - - -
ooooooooooo- - - - -
oooooooooooo- - - -
ooooooooooooo- - -
oooooooooooooo- -
ooooooooooooooo-
oooooooooooooooo
Then during the OFF pulse:
- - - - - - - - - - - - - - - -
Then it switches ON again and the cycle repeats.

Essentially, I want a circuit that when power is applied, lights up a row of LEDs 1 by 1 until they're all lit.

The closest I've seen is a circuit with a 555 timer and two 4017s that would create the following:
- - - - - - - - - - - - - - - -
o- - - - - - - - - - - - - - -
oo- - - - - - - - - - - - - -
-oo - - - - - - - - - - - - -
- -oo - - - - - - - - - - - -
- - -oo - - - - - - - - - - -
- - - -oo - - - - - - - - - -
(and so on and so forth)
Which is still nice, just not quite what I'm looking for.

I feel like it should be simple enough and I'd like to avoid using microcontrollers if possible. I can throw together circuits from schematics, though I may not be able to understand them fully.
 

crutschow

Joined Mar 14, 2008
24,397
It appears simple enough in concept, but the discrete logic to do it does not appear to be.
I think you are probably talking a dozen chips or so with a lot of wiring.
Cutting it back to an 8 or 10 light sequence would help a lot.
 

djsfantasi

Joined Apr 11, 2010
6,189
It appears that you plan on using the existing LED array... Note that it may not be wired to be compatible with the sequence you propose. Each row must be able to be independently controlled.
 

absf

Joined Dec 29, 2010
1,942
There was a thread few years ago about this but I couldn't find it but I still kept the schematics.

It uses 2 x 74HC164 to display 16 LED with pulses from a 555. It would be best to drive the LED through LED drivers like ULN2804 to prevent the HC164 getting overheat. This circuit operates on 5V.

Not sure if there is a CMOS equilvalent of HC164, so the whole circuit can be operated on 12V DC.

ACOLLINS HC164 LED 90%.PNG
Allen
 

crutschow

Joined Mar 14, 2008
24,397
I think I misunderstood your requirements. :rolleyes:
At first I thought you wanted to reset between each partial sequence.
So if you just want to light all 16 LEDs in sequence then afsf's circuit or some variant should work for you.
 

ScottWang

Joined Aug 23, 2012
6,874
I think I misunderstood your requirements.
Me too.
>>What I'm trying to do is to get them to stack/chase with each blink

So I think maybe the TS want a shift and blink function, actually he just want the shifting function, a slowly sawtooth wave and two LM3914 can do as the shifting function.
 

hp1729

Joined Nov 23, 2015
2,304
Hi all,

Before I begin, to mitigate replies about not altering exterior vehicle lighting, etc... This project is for show only and not intended for road use, no ordinances against it, not breaking any codes, all that jazz...
I have a show car with a set of aftermarket tail lights, and the turn signals consist of 16 LEDs arranged in an arrow in the direction of turn.
With the current arrangement they all blink simultaneously like a normal signal.
What I'm trying to do is to get them to stack/chase with each blink, i.e. LEDs go 1 - 1,2 - 1,2,3 - 1,2,3,4 - 1,2,3,4,5 [...] 1,...,16 then after a pause, repeat.
I found some ways to get them to sequence with a 555 timer and two 4017 ICs but I'm not sure how or whether they'd stack as well. Unfortunately my digital-electronics knowledge has all but faded away since school. I've seen a you-tube video with the same lights made to be sequential but the author hasn't responded to my inquiries about the setup.

Any help would be much appreciated.

Thanks.

-AC
How were you going to handle the arrow at the end? A smart solution (like Arduino) gives many options.
 

Attachments

AnalogKid

Joined Aug 1, 2013
8,310
Blink is an ambiguous term. As the pattern travels across the LED array, do you want all LEDs to turn off briefly between each successive stage, adding a flutter effect to the display, or move straight through the pattern with all previously lit LEDs staying on continuously as the pattern progresses?

There is another blinking LED thread on this forum with a slightly different pattern. Depending on the LED current needed for your required brightness, I have a suggestion for LED drivers.

ak
 

gazz

Joined Oct 30, 2009
22
There was a thread few years ago about this but I couldn't find it but I still kept the schematics.

It uses 2 x 74HC164 to display 16 LED with pulses from a 555. It would be best to drive the LED through LED drivers like ULN2804 to prevent the HC164 getting overheat. This circuit operates on 5V.

Not sure if there is a CMOS equilvalent of HC164, so the whole circuit can be operated on 12V DC.

View attachment 100525
Allen
I know this is an old thread, but i want to do the same thing with a slight difference, i want to drive 2 more set of led's, one of which will be in a separate light housing.... i.e. my car has 2 sets of lights side by side on each side for tail, brake and indicators, one light housing is on the (movable) tailgate, the other on the body,

i want the 3 sets of 8 leds in the tailgate (24 total) and the last set of 8 in the body housings, and i want to run as few wires over to the other light housing as possible as they have to go up the tailgate, through the rubber wire channel, across the roof, then down the rear quarter panel to the other light housing.

can i just add another pair 75HC164 and connect what i believe to be 4 wires and a transistor between them?

i'm going to have to drive my led's with transistors or mosfets, as they pull 50ma @ 2.1volts each, any suggestions for the best way to do this?

i'm happy running the circuit on 5 volts, as i will power the whole circuit from a buck regulator to drop the 12 to 16 volts that the car's battery will vary between depending on if the alternator is charging or not to a stable voltage to ensure constant led brightness.

EDIT: i have read that people don't like discussing these things due to laws in some places against these things...

Not sure if it will help, i'm in England, and we have had sequential turn signals allowed since about 2013 when audi fitted them as standard to the A8 model (https://newatlas.com/audi-sequential-lighting-turn-signal/28731/)

since then a lot of new cars over here have them as standard equipment both front and rear... with the fronts the DRL on the side your indicating turns off whilst the orange led's are sequencing.

And my own car if i'd have bought a 2016 or newer model would have had them on the rear from the factory... unfortunately it's a face lift model after 2014, so the lights and bumpers are different from my car's model year...

BUT my insurance company have a selection box on it's online modifications form specifically for "indicator upgrades including sequential/dynamic indicators"
upgrades mean changing tungsten bulbs to led's bulbs, and the sequential bit speaks for it's self, so it's all legal here.
 
Last edited:

gazz

Joined Oct 30, 2009
22
The LM3914 circuit does look simpler, how do you stack them to get say 20 led's lighting up in sequence? and what component changes the timing? as i need to tune them so they all light up pretty fast,
i think the flasher relay is on for 500 milliseconds or so, off for the same (indicators in the uk must flash between 60 and 120 times a minute.. not sure if there's different rules for the sequential ones yet, still looking into that)

I presume i'll still need to use the led drivers ULN2804's, as the amber led's i have run best on 2.1 volts @ 50ma... and can be pulsed at 200ma.. not sure on the pulse duration tho... but i am thinking of making the last led's in the sequence brighter by over driving them, as they will be on for say 100ms and off for 900ms,
 

gazz

Joined Oct 30, 2009
22
Think i figured it out, the LM 3914 is set to bargraph mode, and to read full scale at 12 volts, when it's turned on and fed 12 volts, the led's light up one after the other to display full scale... which is all led's on,

so i presume no way to adjust how fast they light up, but i imagine they will be fairly fast??

Also, will they light up straight away when power is applied? as the hazard flashers need to operate with the ignition off, and i dont fancy powering the chips permanantly.. i know they will likely pull microamps when not displaying any led's tho.
 

olphart

Joined Sep 22, 2012
78
Gazz, you're close: the 56k/2.2u set step speed. This one's for a std flasher wired vehicle, so it takes ~1/2S from dark to all on.
You have to put an equivalent load resistor (~12 ohms) to keep the flasher module functional.
This results in a "sweep" / off / "sweep" behavior. The "DOT" jumper/switch makes them instant all on.
A module with circuit & load resistor is a direct replacement for a std 1157 (or equ) type bulb.
I've even sold a couple sets of a board I made to fit BMW K series rear turn signals.

The 3914 is a constant current driver, so the brightness is consistant.
Number of LEDs is limited by voltage drop and current draw.
 

gazz

Joined Oct 30, 2009
22
Brilliant, thankyou so much for that info,

i've ordered some LM3914's to play with, the switch to make them all turn on at once is cool,
i have an idea to use that function when the ignition is off, so the car lock/unlock indication which is the turn signals being pulsed rapidly a few times will show up better... as if they were going sequentially only the first few led's would light up before the next pulse was given.
 
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