Hello

I think we need to revisit the timing diagram in post #29. Are the following statements correct?

1. L854 timer is “master” timer and resets all other timers

2. Beacon time can be adjusted independently of other timers except master.

3. Floodlight time can be adjusted independently of other timers except master.

4. Obstacle “on” Time is dependent on floodlight time and master.

5. All control outputs are contiguous. That is, one output is always energized except at start or reset.

Questions:

A. What are the additional “time” dependencies ? For example, can be beacon “on” time be longer or shorter than floodlight time?

B. When should auto shutdown begin?

C. Manual shutdown can be initiated anytime after start is initiated?

D. Are you comfortable using AC relays or are DC relays (powered by a wall wart) an option?

E. Are there any failure modes that need to be avoided?

Answers to some of these questions may seem obvious but I want to avoid making assumptions.

eT

 

eT,

I'm not at home right now so it's a bit difficult to give your questions the time and thought they deserve. I'll get back to you in a couple of hours. (PS, all good questions, by the way!)

Harvey

 

Guys:

Did you take a look at that wacky sequencing relay yet? I thought it showed promise.
The inputs can be assigned to multiple segments except for start.

 

Are the following statements correct?

1. L854 timer is “master” timer and resets all other timers.
I wouldn’t call it a “master timer” because all it really does is enable (start and end) the sequence of the three tower lights. The actual sequence will be controlled by the circuit we’re designing.

2. Beacon time can be adjusted independently of other timers except master.
Yes

3. Floodlight time can be adjusted independently of other timers except master.
Yes

4. Obstacle “on” Time is dependent on floodlight time and master.
The Ob Lights should come on after both the beacon and flood lights extinguish, and remain on until the end of the 15 minute enable gate from the 854’s R3 relay.

5. All control outputs are contiguous. That is, one output is always energized except at start or reset.
Yes

Questions:

A. What are the additional “time” dependencies ? For example, can be beacon “on” time be longer or shorter than floodlight time?
Can be but I wouldn’t want a major deviation from the timing chart in post #29

B. When should auto shutdown begin?
About 12 minutes after startup. (This will give the Ob Lights about 3 minutes of “on” time until total system shutdown.)

C. Manual shutdown can be initiated any time after start is initiated?
I think I’m going to delete this option as it may interfere with a pilot's ability to quickly reactivate the beacon if needed.

D. Are you comfortable using AC relays or are DC relays (powered by a wall wart) an option?
AC relays are preferred due to the voltage drop of DC over 150ft. (According to an electrician friend anyway.) Some of the tower’s existing controls are 24VAC so I’d like to keep that as my system standard if possible.

E. Are there any failure modes that need to be avoided?
Yes, I'd like to avoid "Stuck on". No need to annoy the neighbors with a malfunctioning beacon that stays on all night. (Especially since its power comes from my own hangar’s electrical panel!)

 

Are the following statements correct?

1. L854 timer is “master” timer and resets all other timers.
I wouldn’t call it a “master timer” because all it really does is enable (start and end) the sequence of the three tower lights. The actual sequence will be controlled by the circuit we’re designing.

2. Beacon time can be adjusted independently of other timers except master.
Yes

3. Floodlight time can be adjusted independently of other timers except master.
Yes

4. Obstacle “on” Time is dependent on floodlight time and master.
The Ob Lights should come on after both the beacon and flood lights extinguish, and remain on until the end of the 15 minute enable gate from the 854’s R3 relay.

5. All control outputs are contiguous. That is, one output is always energized except at start or reset.
Yes

Questions:

A. What are the additional “time” dependencies ? For example, can be beacon “on” time be longer or shorter than floodlight time?
Can be but I wouldn’t want a major deviation from the timing chart in post #29

B. When should auto shutdown begin?
About 12 minutes after startup. (This will give the Ob Lights about 3 minutes of “on” time until total system shutdown.)

C. Manual shutdown can be initiated any time after start is initiated?
I think I’m going to delete this option as it may interfere with a pilot's ability to quickly reactivate the beacon if needed.

D. Are you comfortable using AC relays or are DC relays (powered by a wall wart) an option?
AC relays are preferred due to the voltage drop of DC over 150ft. (According to an electrician friend anyway.) Some of the tower’s existing controls are 24VAC so I’d like to keep that as my system standard if possible.

E. Are there any failure modes that need to be avoided?
Yes, I'd like to avoid "Stuck on". No need to annoy the neighbors with a malfunctioning beacon that stays on all night. (Especially since its power comes from my own hangar’s electrical panel!)

Hi

OK...I've attached a revised version of the circuit based on your feedback. See attached for the following comments.

1. I've reduced the number of timer relays from previous version. This version requires two Delay On and two Delay Off timer relays.

2. I've tried to eliminate (as much as practical) de-energized closed contacts to help avoid unwanted failure modes.

3. The timing sequence and durations are the same as the previous version.

4. I've removed the manual shutdown function.

5. I've added a "RESET" relay that, when energized, will remove power from all relays. If a relay gets "stuck on" for some reason, at least there will be a way to conveniently reset the circuit. This might not help if the failure is mechanical in nature. Removal of power, of course, could also be accomplished by removal of power at the circuit's power source.

Question:
One thing I noticed is that the "On" duration of the Beacon is not checked in OL circuit. This means that the OL will illuminate if the Beacon is "on" longer than the Floodlight. Is this OK?

eT

 

One thing I noticed is that the "On" duration of the Beacon is not checked in OL circuit. This means that the OL will illuminate if the Beacon is "on" longer than the Floodlight. Is this OK?

I'm having trouble visualizing the scenario but my best guess is that it'll probably be okay.

Harvey

 

Hey eT,

Are you still monitoring this thread? I'm getting ready to order the relays to build a test circuit of your revised schematic (in post #45). However, before placing the order, I thought I'd check to make sure you're comfortable with your revised schematic.

Thanks,

Harvey

 

Hey eT,

Are you still monitoring this thread? I'm getting ready to order the relays to build a test circuit of your revised schematic (in post #45). However, before placing the order, I thought I'd check to make sure you're comfortable with your revised schematic.

Thanks,

Harvey

Hi

The circuit has only been tested as a simulation but I have no reason to believe it won't work as a real circuit.
As long as your comfortable with it, I'm comfortable with it.

eT

 

As long as your comfortable with it, I'm comfortable with it.

I understand and accept your terms.

Harvey

 

eT

Off-line Conversation sent.

Harvey