• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

taillight sequencer ?????

Status
Not open for further replies.

boolagoosh

New Member
I am attempting to create a device to light a row of leds about 20 wide as follows

leds---- 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
circut---0 1 2 3 4 5 6 7 8 9 9 8 7 6 5 4 3 2 1 0

When supplied with a constant 12 volts, I want the 9s to light up first, joined next by the 8s, then the 7s etc........

it will start small and grow out as more leds turn on.

its for a third brake light in my car :?:
 

kinjalgp

Active Member
You can either use a specially designed counter using discrete logic ICs or a single microcontroller like 89C2051 or PIC16F84 (simplest to program) to do it.
 

john1

Active Member
Hi boolagoosh,

You say you want to create a device for this?
I wouldn't be surprised if there isn't already something available.
You could probably purchase programmable chips that would give
the result you want, i guess the extra tail-light is quite a bright
set of LED lamps, so they would need extra boosting from whatever
'cascade' unit you make anyway.

This is the sort of approach i would take to give the result
you describe.

The bottom part of a charging capacitor's curve is fairly linear,
so ive guessed at about three volts, but you might want it
non-linear!

The circuit is not finished, it is only a suggestion, you
would have to sort the details, its just the sort of way i would
go about it.

It might be easier to buy something ready-made
than to create your own.

Regards, John
 

Attachments

bogdanfirst

New Member
how about using a 20(or 22) counter and some buffers and connect a capacitor for each output of the counter to the buffer, something like 10u or so, try more values, it seamas easier than using a bucket of transistors.
 

kinjalgp

Active Member
Instead of using 20(or 22) Counters how about using a single chip microcontroller :wink:
 

bogdanfirst

New Member
well its simple to use a microcontroller if you know how to program one. i dont know a thing about programming, but i intend to learn in dummer.
of course you can make more affects with a controller, but where s the fun.????/
 

herbymcduff

New Member
go with what kinjalgp said. Programming is easy, and not hard to learn in a matter of hours. If you have Basic, your program is about simple. If you use a microprocessor, you need to know machine language. Your circuit gets easier if you were to use a PIC.
 

Sarac

New Member
boolagoosh said:
I am attempting to create a device to light a row of leds about 20 wide as follows

leds---- 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
circut---0 1 2 3 4 5 6 7 8 9 9 8 7 6 5 4 3 2 1 0

When supplied with a constant 12 volts, I want the 9s to light up first, joined next by the 8s, then the 7s etc........

it will start small and grow out as more leds turn on.

its for a third brake light in my car :?:

Hi, Boolagoosh,

The attached diagram shows how to wire 16 leds to light up one ofter another. First led remain lit till the 16th led light up and all of them go off then the cycle restart. Of course you've got to wire another parallel row of 16 leds for oposit direction.

I think this is exactly what you want.

hope this will help your project


regards,
 

Attachments

kinjalgp

Active Member
I think the above circuit will only lit the LED in sequence but he also wants them to go off in reverse sequence and I don't think this will do the reverse thing.
 

Sarac

New Member
kinjalgp said:
I think the above circuit will only lit the LED in sequence but he also wants them to go off in reverse sequence and I don't think this will do the reverse thing.
Sure, that the circuit will lit the LED in sequence only. All leds go off at the same time, not getting them off one by one in reverse.

But Boolagoosh didn't mention the reverse effects anyway.

I think it can also be done but not with this circuit. i have idea to obtain such effect with circuits contain tristors, transistors and IC Combination. But it still need to be work on it.
 

kinjalgp

Active Member
Ofcourse he has mentioned the revese effect. See: 123456789 and then 987654321
 

Sarac

New Member
kinjalgp said:
Ofcourse he has mentioned the revese effect. See: 123456789 and then 987654321

ok you may be right but i thought he wants leds should be put on 2 by 2.
both 9th led will be lit at the same time and then 8th and then 7th
so he would have two running light proceeding to oposit direction since he said " I want the 9s to light up first, joined next by the 8s, then the 7s etc........"

anyway it may help to somebody else if boolagoosh didn't mean what i mean

sorry,
 

bogdanfirst

New Member
from what i see the order, its like putting the leds in circle and one led lights and then another.....but some leds remain lit up for some time afer they had lit.
 

kinjalgp

Active Member
Seems we all are becoming taillight designers with new super bright ideas. :lol: Let boolagoosh tell us what he wants before any new model comes up ;)
 

john1

Active Member
Hi boolagoosh, kinjalp, bogdanfirst, herbymcduff,
Sarac, and any others looking in,

Apparently 'Halfords', a popular car-spares shop
sell ready made units to do just this effect.

This would probalbly be cheaper than buying all
the bits, and a case, and spending the time to
build one yourself,

But projects like this are usually taken on where
the person wants to make it themselves, people
are usually aware that ready made items are
available.

Building something from discrete components is a
far cry from programming nested loops into some
programmable chip, that may not be what he wants.

As to the reverse effect,
it is assumed that they will all go out, wherever
they are in their sequence, opon release of the
brake pedal. That seems logical to me.

Sarac is correct, the circuit as drawn, is for
lighting the LEDs in the manner described, they would
all go out together.

Also as mentioned, the circuit is only a skeleton,
only a suggestion, it may be found that high to med
value resistors need to be put between the base-
emitter junction of the outputs, to keep them shut
when not being driven, if the leakage from the drivers
is a bit high.
And the cap doesnt want to be too big, cos it has to
empty fairly quickly when the supply goes off, it
would be feeding the LEDs so it would empty quickly
anyway, i mention it because there are capacitors
available which are such massive values that using
a very large value could actually make a visible
delay between releasing the brake, and the lights
going out. Unlikely, but best mentioned.

For someone wanting to 'learn as they go' such a
project is fairly good, easy to fault-find, no
RF, no dificult to understand parts, moderately
easy to understand, and gives a visible result to
satisfy the constructor.

John
 

Phasor

Member
Ok, here's a challenge for you all - I have designed a logic circuit to do this - it lights them in sequence, then turns them off in reverse - using only flip-flops and AND gates (+ a clock source)

I wonder if any else here can figure it out :twisted: . I'll give you a hint - for 10 LEDs, I used 11 J/K flip flops and 20 AND gates.

BTW, it's not very compact, that's why I set this challenge, rather than post the circuit here (I can't fit the whole picture on the screen) :lol:

I shall be greatly impressed if you can use less logic than I did, without resorting to anything more advanced than flipflops (such as up/down counters, microprocessors etc).
 

kinjalgp

Active Member
No big deal! :) Its a matter of 15 minutes to design a synchronous counter for ANY given sequence using flip-flops. Because of complexity of this circuit (at-least 10 ICs or more), I have not suggested it. And since we have an easy solution out there why not use it.
What do you think 10 ICs or 1 uC ??
 

Phasor

Member
Yeh, ok, point taken, kinjal - but I was hoping for a reply from someone with less experience - I just thought it was a good learning exercise.

Of course I wouldn't build it that way, either. U/D counter is far simpler. I'm only trying to tickle the brain cells.
 

bogdanfirst

New Member
well, i think you only need a clock source, a counter with enough outputs for the leds and a FF for each led.?for 20 leds i think about 7 ics considerring 2 FF in an IC. maybe you can make it simpler.
 

boolagoosh

New Member
Hi
sorry for my latency. I did not intend for the leds to shut off in reverse order, but it would be cool if it was easy.
 
Status
Not open for further replies.

Latest threads

EE World Online Articles

Loading
Top