DESIGNING AN AIRFIELD LIGHTS CONTROLLER (Second try)

Howdy Guys,

I need some advice in designing and building a circuit that will sequentially turn on three lights and after a preset time, sequentially turn them back off. The lights are part of an airfield lighting system on a private residential airport. I originally posted this request on AAC about half a year ago ( https://forum.allaboutcircuits.com/...ling-the-lights-at-a-private-airfield.148305/ ) but that thread languished and ultimately died, largely because I was unsure of what I wanted to accomplish at the time. While that thread attracted several helpful replies, I've decided to start a new thread to keep the old discussion from creeping in and confusing things! Please note that since our runway is restricted (not open to regular public-use) the FAA doesn't approve or disapprove such installations other than to offer guidance.

The purpose of the three light systems are to aid an inbound pilot in locating our runway at night and determining the wind direction and intensity prior to landing. The lights will be turned on by the inbound pilot keying his/her communications microphone 5 times within 5 seconds on a designated frequency (an FAA standard). After landing, the pilot can extinguish the lights by clicking his/her mic another 3 times, or the lights will automatically extinguish after 12-15 minutes. A professionally-built ground-based receiver/decoder for receiving the pilot’s mic clicks (aka “squelch breaks”) has already been purchased but I still need to build the light sequencer and timer.

The sequencer/timer that I need to build should function as follows:

1. Upon receiving and decoding the pilot’s mic clicks, an internal set of “dry” SPDT contacts will change state for 1, 15, 30 or 60 minutes (selectable during system installation) and will immediately activate our rotating beacon.

2. 2-5 seconds later (the actual delay will be determined after initial system installation and testing) the windsock’s floodlight will illuminate, thus completing the “turn on” sequence.

3a. The “automatic shutdown” sequence will start 10-15 minutes later (again, determined by system testing). The windsock’s floodlight extinguishes first and the rotating beacon will extinguish 2-5 seconds later. At the same time the beacon extinguishes, the obstacle lights on top of the tower will illuminate and remain illuminated for 5 minutes.

- or -

3b. The system can be shut down manually by the pilot by clicking his/her mic 3 more times after the turn on sequence has completed. (This will toggle a different set of SPDT contacts within the receiver/decoder unit.) Other than shutting down earlier than the automatic sequence (3a) the manual shutdown sequence will be the same order as the automatic sequence.

Notes:
1. All lights and the rotating beacon will be activated via heavy duty relays, lighting contactors. or solid state relays located at the top of the 42ft rotating beacon tower.

2. The Receiver-Decoder unit, as well as all other beacon controls, will be located in a hangar 150ft away. All tower power circuits are 110VAC and the control circuits are 24VAC. Twenty 16ga "signal" wires and five 12ga "low voltage power" wires in underground conduits connect the control unit in the hangar to the relay cabinet at the top of the beacon tower

3. All of my designs so far have been based around commercially-available "delay" relays because a “simple” sequencer is preferred over one that requires complicated programming. That said, I’m not totally against a “Smart Relay” or Arduino, providing that I don’t have to call NASA for help in troubleshooting the system!

Unfortunately, all of my designs so far have turned out amazingly way-overcomplicated! (A simple circuit somehow eludes me!!!) Your help is greatly appreciated!

Harvey

 

Two approaches -

1) C code a standard UP

2) Basic code a UP like ATTINY using bascom interpretor

https://www.mcselec.com/


3) State machine either using Verilog or using State Machine Wizard
in PSOC.

Couple state machine to onboard timers.


Regards, Dana.

 

DESIGNING AN AIRFIELD LIGHTS CONTROLLER (Second try)

Howdy Guys,

I need some advice in designing and building a circuit that will sequentially turn on three lights and after a preset time, sequentially turn them back off. The lights are part of an airfield lighting system on a private residential airport. I originally posted this request on AAC about half a year ago ( https://forum.allaboutcircuits.com/...ling-the-lights-at-a-private-airfield.148305/ ) but that thread languished and ultimately died, largely because I was unsure of what I wanted to accomplish at the time. While that thread attracted several helpful replies, I've decided to start a new thread to keep the old discussion from creeping in and confusing things! Please note that since our runway is restricted (not open to regular public-use) the FAA doesn't approve or disapprove such installations other than to offer guidance.

The purpose of the three light systems are to aid an inbound pilot in locating our runway at night and determining the wind direction and intensity prior to landing. The lights will be turned on by the inbound pilot keying his/her communications microphone 5 times within 5 seconds on a designated frequency (an FAA standard). After landing, the pilot can extinguish the lights by clicking his/her mic another 3 times, or the lights will automatically extinguish after 12-15 minutes. A professionally-built ground-based receiver/decoder for receiving the pilot’s mic clicks (aka “squelch breaks”) has already been purchased but I still need to build the light sequencer and timer.

The sequencer/timer that I need to build should function as follows:

1. Upon receiving and decoding the pilot’s mic clicks, an internal set of “dry” SPDT contacts will change state for 1, 15, 30 or 60 minutes (selectable during system installation) and will immediately activate our rotating beacon.

2. 2-5 seconds later (the actual delay will be determined after initial system installation and testing) the windsock’s floodlight will illuminate, thus completing the “turn on” sequence.

3a. The “automatic shutdown” sequence will start 10-15 minutes later (again, determined by system testing). The windsock’s floodlight extinguishes first and the rotating beacon will extinguish 2-5 seconds later. At the same time the beacon extinguishes, the obstacle lights on top of the tower will illuminate and remain illuminated for 5 minutes.

- or -

3b. The system can be shut down manually by the pilot by clicking his/her mic 3 more times after the turn on sequence has completed. (This will toggle a different set of SPDT contacts within the receiver/decoder unit.) Other than shutting down earlier than the automatic sequence (3a) the manual shutdown sequence will be the same order as the automatic sequence.

Notes:
1. All lights and the rotating beacon will be activated via heavy duty relays or lighting contactors at the top of the 42ft rotating beacon tower.

2. The Receiver-Decoder unit, as well as all other beacon controls, will be located in a hangar 150ft away. All tower power circuits are 110VAC and the control circuits are 24VAC.

3. All of my designs so far have been based around commercially-available "delay" relays because a “simple” sequencer is preferred over one that requires complicated programming. That said, I’m not totally against a “Smart Relay” or Arduino, providing that I don’t have to go to NASA for help!

Unfortunately, all of my designs so far have turned out amazingly way-overcomplicated! (A simple circuit somehow eludes me!!!) Your help is greatly appreciated!

Harvey

All airfields should comply to regulations including their lighting.
for the US https://www.faa.gov/airports/engineering/construction_standards/

I assume that not complying to the standard could put the airfield owner into trouble and could lead to exclusion of insurance.

Picbuster
Yes, regulation and laws will make life miserable!!

 

Define the inputs and the outputs and maybe not in the traditional sense.

You might have a state in your flowchart that says:

Shutdown sequence received. -or-
Start-up sequence received.
You might create "variables" as you enter certain states.

You need some sort of state diagram or at least a flow chart.

There may be a "test mode" too.

The 150 feet feet of multiple 24 Vac type of contacts might actually be yuk!

There is a protocol called MODBUS that operates on RS-485, Ethernet or Fiber.

You need some sort of "cable diagram". I had a few cabinits to wire and I had the electricians run the wires. There were not a lot of cables.
My stupid list would have something like 3J2 (originates at 3); cable J; The other end was 2J3. It gave me the idea of what wires were required.

You may be automating something existing or you may not be.

If, indeed you have say 7 things 150 feet away, using fourteen conductors of a length of 150' cables is not necessarily a good thing.
Fiber/Wireless is a possibilty.

There is some stuff here: http://www2.advantech.com/industrial-automation/ particularly ADAM modules.

then www.automationdirect.com

I ran into LabView for embedded recently and it's definitely different. http://sine.ni.com/nips/cds/view/p/lang/en/nid/212478. I've used LabView before, but not like that set-up. Aparently, you can develop with the PC and an embedded system together and then run the embedded system stand-alone. really wierd.

LabView was different. I learned it early when there were little resources and it was Macintosh only. It was at the time becoming cross-platform.
It's the de-facto standard for automating Instrumentation and doing measurements. it's quick if and only if, the instrument drivers exist. When you have to develop an instrument driver, development slows considerably.

The cool part, is you can have the interface act as a web server very easily.

I still don't think a bunch of timers is going to cut it.






This thing should be simple enough for someone else to fix.

 

DESIGNING AN AIRFIELD LIGHTS CONTROLLER (Second try)

Howdy Guys,

I need some advice in designing and building a circuit that will sequentially turn on three lights and after a preset time, sequentially turn them back off. The lights are part of an airfield lighting system on a private residential airport. I originally posted this request on AAC about half a year ago ( https://forum.allaboutcircuits.com/...ling-the-lights-at-a-private-airfield.148305/ ) but that thread languished and ultimately died, largely because I was unsure of what I wanted to accomplish at the time. While that thread attracted several helpful replies, I've decided to start a new thread to keep the old discussion from creeping in and confusing things! Please note that since our runway is restricted (not open to regular public-use) the FAA doesn't approve or disapprove such installations other than to offer guidance.

The purpose of the three light systems are to aid an inbound pilot in locating our runway at night and determining the wind direction and intensity prior to landing. The lights will be turned on by the inbound pilot keying his/her communications microphone 5 times within 5 seconds on a designated frequency (an FAA standard). After landing, the pilot can extinguish the lights by clicking his/her mic another 3 times, or the lights will automatically extinguish after 12-15 minutes. A professionally-built ground-based receiver/decoder for receiving the pilot’s mic clicks (aka “squelch breaks”) has already been purchased but I still need to build the light sequencer and timer.

The sequencer/timer that I need to build should function as follows:

1. Upon receiving and decoding the pilot’s mic clicks, an internal set of “dry” SPDT contacts will change state for 1, 15, 30 or 60 minutes (selectable during system installation) and will immediately activate our rotating beacon.

2. 2-5 seconds later (the actual delay will be determined after initial system installation and testing) the windsock’s floodlight will illuminate, thus completing the “turn on” sequence.

3a. The “automatic shutdown” sequence will start 10-15 minutes later (again, determined by system testing). The windsock’s floodlight extinguishes first and the rotating beacon will extinguish 2-5 seconds later. At the same time the beacon extinguishes, the obstacle lights on top of the tower will illuminate and remain illuminated for 5 minutes.

- or -

3b. The system can be shut down manually by the pilot by clicking his/her mic 3 more times after the turn on sequence has completed. (This will toggle a different set of SPDT contacts within the receiver/decoder unit.) Other than shutting down earlier than the automatic sequence (3a) the manual shutdown sequence will be the same order as the automatic sequence.

Notes:
1. All lights and the rotating beacon will be activated via heavy duty relays or lighting contactors at the top of the 42ft rotating beacon tower.

2. The Receiver-Decoder unit, as well as all other beacon controls, will be located in a hangar 150ft away. All tower power circuits are 110VAC and the control circuits are 24VAC.

3. All of my designs so far have been based around commercially-available "delay" relays because a “simple” sequencer is preferred over one that requires complicated programming. That said, I’m not totally against a “Smart Relay” or Arduino, providing that I don’t have to go to NASA for help!

Unfortunately, all of my designs so far have turned out amazingly way-overcomplicated! (A simple circuit somehow eludes me!!!) Your help is greatly appreciated!

Harvey

Hi

You've mentioned a few selectable timeouts.
What comes to mind is using cascaded IC timers.
But what type of precision is required for the timers?

eT

 

Danadak and KISS,

Thanks for your inputs but you're both talking waaaaayyyyy over my head! Note my reference to "Delay Relays" in my initial post. THIS is the kind of technology that I'm familiar with!

Harvey

 

All airfields should comply to regulations including their lighting.

Picbuster,

Please note that I stated in my opening post that the FAA doesn't regulate non-public-use airports. It only offers suggestions and guidance.

Harvey

 

eetech00,
You and I are practically on the same page but I was thinking of a single-cycle CMOS ring-counter with pick-offs. A provision for resetting it to the beginning at any time would be necessary too.

None of the times that I spoke of are critical.

Harvey

 

eetech00,
You and I are practically on the same page but I was thinking of a single-cycle CMOS ring-counter with pick-offs. A provision for resetting it to the beginning at any time would be necessary too.

None of the times that I spoke of are critical.

Harvey

Yes....if the time tolerance is not critical, then a timer like a CD4060 with an RC oscillator might do the job. Or maybe some cascaded RC timers. The timer output logic could be opto-coupled, or drive small relays to interface with the 24VAC control circuits.

But a tower that high.....what about lightning strikes?

What does the lighting circuits look like? Any existing wiring diagrams?

What is the lighting sequence for the lights? (on)1->2->3, (off)1->2->3...?

Are the time settings variable(for example, anywhere between 1s and 15s) or fixed values ( 1s or 5s or 10s or 15s)?

eT

 

eetech00 said:
"If, indeed you have say 7 things 150 feet away, using fourteen conductors of a length of 150' cables is not necessarily a good thing.
Fiber/Wireless is a possibility."

RabbitH said:
While burying long lengths of copper wire may seem archaic to some, remember that the phone companies have buried copper cables (often without the luxury of conduit) all over the country. Therefore, my 150ft of wires in conduit should easily outlast me and probably my grandkids.

It may be helpful to tell all of you that our beacon tower is an 85 year old survivor of America's 1930s Lighted Airway Beacon System (relocated to our airport from one of the southeast Texas airway route segments). While it is now being used as an airport beacon (aka a "terminal" beacon) instead of cross-country navigation, every attempt to remain faithful to its heritage is being taken, as we are able. For example, the original timer for these lights was a motor-driven rotating cam with microswitch pick-offs. However, this system required a lot more maintenance than we want to deal with so we're willing (reluctantly) to update it with solid state technology that's more reliable. However, we're not ready to embrace fiber or WiFi yet if we don't have to because we desperately need to limit our modifications to technology that a bunch of 60-something-year-old retirees are capable of maintaining !

eetech00 said:
But a tower that high.....what about lightning strikes?

RabbitH said:
Good point because Texas is, indeed, in America's Thunderstorm Alley and my tower will undoubtedly be a 42ft lightning magnet. To protect against strikes, I followed recommended standards for protecting communications towers. ​

If you’re interested in the old airway beacon system or my restoration and relocation of one of its towers, check out…

The short version...
https://thesurveystation.com/2017/01/29/the-story-behind-our-new-beacon-tower/

or the long version...
http://www.dreamsmithphotos.com/arrow/States/tx/skylake.html

Harvey

​

 

Maybe, that it. A multi-cam rotating timer with say weird abilities like reversing quickly?

just a thought...

Just remember, I'll throw out everything when I'm brainstorming.

 

eetech00,
You and I are practically on the same page but I was thinking of a single-cycle CMOS ring-counter with pick-offs. A provision for resetting it to the beginning at any time would be necessary too.

None of the times that I spoke of are critical.

Harvey

Hi

So...here is a first pass at designing the circuit.

Keep in mind that the timer ICs are not precision timers so will require adjustment. I've shown (6) 555's but they can also be (3) 556's (dual timer IC).
The circuit is basically a sequencer made up of cascaded timers. I followed your description the best I could but some things were still a little fuzzy.

I've attached a preliminary schematic.
The inputs from control contacts connect to optocouplers, so the signal can be 24 vac.
I haven't shown the output interface circuits because I'm not sure what is being driven.
I've also shown a manual shutdown input that can initiate shutdown after the startup sequence completes.

I've attached a graph showing the timing sequence. Although its a little difficult to see, there is a 5 second delay from the time the beacon activates and the FloodLight activates.The obstacle lights remain on 5 minutes after the beacon shutsdown.
Time is shown in minutes across the bottom of the graph.

Please review. Let me know if you would like to pursue this.

I'm sure you'll have questions...

Edit: Updated Schematic and included .PDF for easier viewing. 8/17/2018

eT

 

eT

I saw your circuit just as I was shutting down my computer for the night. My initial assessment is that we might need to tweak some of the timing a little but I already appreciate the effort that you've put into the design!!!

See you in the morning,

Harvey

 

This is just a suggestion, but surely a simple microcontroler would be the easiest option? (Arduino as you suggest)
Then you could directly connect any SPDT contacts (5v from the Arduino straight back and into an input, by my calculations you will lose 0.8v max over that cable length). Then if you are driving solid state relays you can literally connect them directly to an Arduino output, or for any other option you can just add a relay board. The program for this would be nice and simple, and there is plenty of help available on the Arduino forum as well as this one.

 

eT

I saw your circuit just as I was shutting down my computer for the night. My initial assessment is that we might need to tweak some of the timing a little but I already appreciate the effort that you've put into the design!!!

See you in the morning,

Harvey

Hi

Just so you know..
The timing is adjustable and it follows the timing sequence described in post #28 of this previous discussion:

https://forum.allaboutcircuits.com/...he-lights-at-a-private-airfield.148305/page-2

eT

 

eetech00 Said:
Just so you know..
The timing...follows the timing sequence described in post #28...

I see that now. The 5sec delays aren't very pronounced on a graph that goes to 15minutes.

Harvey

 

This is just a suggestion, but surely a simple microcontroler would be the easiest option? (Arduino as you suggest).

Blue,

I have to admit that on first glance, eetech00's digital circuit looks to be reminiscent of the overcomplicated circuits that I kept coming up with on my own before turning to AAC, but I also said somewhere earlier that my VCRs flashed 12:00 throughout the 1990s because programming, and its inevitable REprogramming, aren't my forte! And while I understand that help will probably always be just a couple of clicks away on AAC, I prefer a troubleshooting solution that I can easily understand and implement myself.

That said, I haven't completely closed the door on an Arduino-based solution, or eT's IC chip-based circuit. However, recall that plug-in electromechanical delay relays (or the like) are about as complex as I wanted to go with this if possible. That's because I want to be able to walk out to my hangar with little more than my trusty Simpson 360 to get a malfunctioning beacon back into operation.

Harvey

 

Blue,

I have to admit that on first glance, eetech00's circuit looks to be reminiscent of the overcomplicated circuits that I kept coming up with on my own before turning to AAC, but I also said somewhere earlier that my VCRs flashed 12:00 throughout the 1990s because programming, and its inevitable REprogramming, aren't my forte! (And while I understand that help will probably always be just a couple of clicks away on AAC, I prefer a troubleshooting solution that I can easily understand and implement myself if necessary.

That said, I haven't completely closed the door on an Arduino-based solution, or eT's IC chip-based circuit. However, recall that plug-in electromechanical delay relays (or the like) are about as complex as I wanted to go with this (if possible). That's because I want to be able to walk out to my hangar with little more than my trusty Simpson 360 to get a malfunctioning beacon back into operation.

Harvey

hello again...

While the circuit looks over complicated, it really isn’t. Most of what you need to know is how a 555 timer works. Each timer circuit is basically identical..so if you know how one works it’s easy to understand the rest.
What was difficult for me was understanding the desired timing sequence. I could have done this with a PIC micro controller but still would need to understand the timing sequence.
Hopefully I came close....I actually found the timing diagram you posted after I posted the circuit.
Oh...and yes...you’ll be able to trouble shoot it with a Simpson 260
( I used to have a Simpson 262)

eT

 

Thanks eT,

There's a possibility that the simple solution that I'm seeking doesn't exist. Therefore, I may HAVE to step up to something a little more complicated.

 

Just throwing another idea out there...

plug-in electromechanical delay relays (or the like) are about as complex as I wanted to go with this

Ok, so let's design a circuit to work only on relays. To do what you need, we essentially need a way of daisy chaining time delay relays so that when one goes off it starts the next. Supposing your timer relays are DPDT, you would also need another load of standard DPDT relays, I think the attached should work (I haven't tested). This supposes the bottom row of relays are the time delay ones, and the top row are standard ones. The input to start the sequence is the connection on the lower left, and the input to cut the sequence is on the upper right. How it works, is that the first time delay relay turns power on to the standard relay, which latches itself once it has switched on (not a latching relay). When the first time delay relay goes off the standard relay stays on, therefore providing power down to the common, which connects through the NC contact to trigger the second time delay relay. This then turns on the second standard relay, which turns off the first standard relay and ends the input pulse to the second time delay relay, and so on.