# Need Help on Building Airport Runway...

Discussion in 'The Projects Forum' started by asantos3412, Feb 26, 2010.

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1. ### asantos3412 Thread Starter Member

Feb 26, 2010
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hey guys...im new this this whole forum and everything...

im been goin over everything...and lookin in a whole lot of books trying to figure out how to build a airport circuit...

i am somewhat familiar with 4017 chips and toggle switches and 555 timer chips....but i need to create an aiport runway circuit like the one found here http://www.bakatronics.com/images/PICT0040RS2.jpg
and if you are familiar with the lax pylons.. http://gyst-ink.com/blog/wp-content/uploads/2008/09/lax2.jpg

for the pylons we can use about 6...we dont actually need all of them...
not really sure how to set the relay to light up all six at the same time..

and for the runway it could be around 6 in each side...lighting up one by one and if its possible after all at the same time..

any help would be appreciated...

not sure how exactly to build the circuit..im good in seeings schematics and building it on a breadboard...

but not exactly sure...

much thanx

2. ### SgtWookie Expert

Jul 17, 2007
22,183
1,728
So, do you want them to turn on individually in sequence, and once all on, to also turn off individually in sequence?

Or once they are all on, turn them all off?

Mar 24, 2008
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4. ### asantos3412 Thread Starter Member

Feb 26, 2010
49
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well i need them to turn on since they are both parallel....in each side...
turn on in line one by one...and once the line finishes...all together...
then turn off and start all over..

5. ### SgtWookie Expert

Jul 17, 2007
22,183
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Here you go. See the attached.

You'll need to calculate the current limiting resistors for the LEDs that you are using.

I suggest you use a 10v to 16v regulated supply.
[eta]
Your LEDs will have a rating for typical Vf @ current. A white LED might have a typical Vf of 3.4v@20mA.
The ULN2004A is a 7-channel Darlington driver IC. It's overkill for this project, but that is OK - it makes building it very simple, because it eliminates lots of parts. You could also use a ULN2804A IC, which has 8 channels instead of 7.
So, to calculate the LED current limiting resistors:
Rlimit >= (Vsupply - (Vf_LED_total + 0.7v)) / Desired_Current

So, for example; two LEDs in series rated 3.4v@20mA with the ULN2x04A driver, and if your Vsupply is 12v:
Rlimit >= (12v - (3.4v+3.4v+0.7v))/20mA
Rlimit >= (12v - 7.5)/0.02A
Rlimit >= 4.5/0.02
Rlimit >= 225 Ohms. That is not an E24 standard value of resistance, so you go to the next higher standard value that you have available.
Here is a page with standard resistance values: http://www.logwell.com/tech/components/resistor_values.html
Bookmark it.
240 Ohms is the closest standard E24 value. If you don't have them, you could always use two resistors in series to add up to a resistance >= 225 (like a 150 Ohm + 75 Ohm = 225 Ohms).

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Last edited: Feb 27, 2010
6. ### asantos3412 Thread Starter Member

Feb 26, 2010
49
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ok...thanx alot
i mostly inderstand the schematics..
but i have a question..i know its kinda dumb question..but whats the difference between the vss and vdd...

i never really understood that consept..if i were to connect the breadboard to the function generator...would i need to connect something else..

and also...in skool they just gave us a couple of ic chips...would i be able to use a 4017 ic chip instead of an 4015...

would i also be able to use this schematics for the pylons of the lax..idk if your familiar with those..

heres a pic of how their supposed to look...

pretty much they have to be 6 in a circle and all turn on at the same time...

but thanx so much for the info

7. ### SgtWookie Expert

Jul 17, 2007
22,183
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Yeah, Vdd/Vcc/Vss/Vee - that's confusing at first.
Vcc is to transistors as Vdd is to FETs. So, you can think of Vcc=Vdd.
Vee is to transistors as Vss is to FETs. So, you can think of Vee=Vss. It's always more negative than Vcc/Vdd.

Sometimes, as in this circuit, there is no need for a "real" negative voltage. However, Vss is shown in the supply connections as being equal to ground.

The circuit as shown does not need an external clock. The 555 timer provides the clock.

The 4017 is a 5-stage Johnson counter. It might be used, but the logic will get ugly. You would also need some other gates along with the 4017.

OK, so the pylons all turn on at the same time. Do they flash, like the runway lights?

I don't know, I haven't been to LA in over 15 years. I used to have an office that overlooked the LAX runway, and they didn't have pylons back then.

8. ### asantos3412 Thread Starter Member

Feb 26, 2010
49
0
ohh ok then...thanks..that was alot of help ill keep that in mind..

umm no the pylons just turn all on at the same time..and stay on for a few seconds then turn off then start the sequence over...just all on then off..

the pylons look like this..
http://www.dcaslideregistry.com/slides/1762fQzIIp.jpg

i only really need to put 6 or so in a circle..

ohh ok...well ill keep that in mind..and what about the 2004 ic chip..is there any other alternative for that chip cuz i doubt i have that 1 as well...

Last edited: Feb 27, 2010
9. ### Wendy Moderator

Mar 24, 2008
20,772
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A 4017 can handle 10 outputs, so it should work pretty well. It can also drive 10ma (though this can be debated, it is speced at 6.8ma), and you can put 2 LEDs in series as is shown before.

Of course, I'm not sure what I'm looking in the pylon picture.

10. ### asantos3412 Thread Starter Member

Feb 26, 2010
49
0
well thats just a picture of how the pylons are..lol

i need a schematics of how to put them all together..and make a circle...

i need them to turn on all at the same time and then reset and keep turning bak on and off all together..

im just not sure how to put it together..

11. ### asantos3412 Thread Starter Member

Feb 26, 2010
49
0
is there any led light that i may be able to use that wen turned off and bak on they change color or something close to that..or is there only single color led lights

12. ### SgtWookie Expert

Jul 17, 2007
22,183
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Sure there are, but you seem to be limited to what you have been supplied by the school.

You've rejected my schematic, which will do just what you initially asked for with no other components.

Now you want to use a 4017, which will require LOTS more components.

I don't know for certain if you understand the difference between a 4015 and a 4017, but I suspect not.

The 4017 could be used, but the effect will be very different. Only one LED (on either side of the runway) will be lit at a given time. If you want them to come on progressively (either side lit up from the start to the end) then you will need to add lots more components.

Bill_Marden, the 4017 should not really be used to source current for LEDs. I know that it can be done for projects that one doesn't care about, but it violates the specifications in the datasheets, and that is not a good practice to pass on to our n00bs.

asantos3412 likes this.
13. ### asantos3412 Thread Starter Member

Feb 26, 2010
49
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yes i have been limited...and thats whats frustrating me...

and no of course not..for no reason am i rejecting the schematics...i really appreciate the work..i hope i can pull it off..i was trying to put things together yesterday on certain things that i know i have already....

but i wasnt sure if i needed to exactly use only parts that we have on out kit..or components supplied to us..that was my only concern..but i emailed my professor and he said we can use whatever we want as long as we get it done..so i am planning on going to fryes tomorrow and buying some new ic chips and well other things i might need...

but thanks a lot for the help i really appreciate it...

now for the pylons schematics...would i also be able to use the same schematics as the runway..

because i dont really need them to flash one at a time..they are gonna be in a circle..im guessing around 6 leds...and all i really need them to do is just all turn on at the same time and then off...
and reset and keep turnin on and off by themselves without having to use a switch...

but like i said...youve been help enough...thanks anyways

14. ### Wendy Moderator

Mar 24, 2008
20,772
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If this were a college course I would agree with you, but it is not. I've been doing it for a very long time. I agree we need to make sure the OP and other know it is not the best of practices, but it is out there on the web (and here too since I write).

Are there any videos of what these pylons are doing? It looks interested in stills.

15. ### SgtWookie Expert

Jul 17, 2007
22,183
1,728
Here is the same schematic, revised to add the pylon lights.

The pylons will turn ON at the same time the 4th runway light comes on, and turn off when the runway lights go off.

If you want them to come on earlier or later, just move the connection for IC3 pin 7 to a different input pin.

[eta]
Note that the power pins for the 4015 are not shown on the schematic.
Connect pin 16 to Vdd (+V)
Connect pin 8 to Vss (GND)

• ###### RunwayLightSequencer2b.png
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Mar 24, 2008
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17. ### hgmjr Moderator

Jan 28, 2005
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As I remember the behaviour of the pylons when I viewed them from my hotel window just across the highway, these pylons slowly shift their color through a palette of several different hues. They sequence around the circle in a seemingly unlimited variety of patterns. The effect at night is visually striking.

Are you looking to reproduce the color changes as well?

hgmjr

18. ### Audioguru New Member

Dec 20, 2007
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Sgt Wookie,
What is wrong with driving LEDs from the outputs of a CD4017 or any other CD4xxx IC? The outputs are rated for 100mW and can source up to 18mA.

19. ### Wendy Moderator

Mar 24, 2008
20,772
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Actually the spec I saw was 6.8ma for the 4017, then there is the 50% rule.

Question for the OP:

Do you have multicolor LEDs, all three colors in separate packages? I have some PWM projects that might apply here, generating lots of colors not quite randomly with not too much circuitry. The expensive part is the LEDs.

20. ### asantos3412 Thread Starter Member

Feb 26, 2010
49
0

im sorry...what exactly do you mean by multicolor LEDS...

I have separate LEDS...varying colors...have some red ones, green ones, and blue ones..just whats included in the kit..

but is there any LED lights that can change color...like a clear LED that changed color or would i need different LEDS...

im willing to buy some LEDS...i was about to step out to FRYES to check out if they might have some IC and other components i may need...but please send me the schematics..i am willing to try anything...im in such a tight schedule..i need to finish this by tuesday night..