[TowerTalk] Motorized tower auto-lower

[Dave]

Since there have been a number of responses, I will address each here in
summary rather than individually.

First off, it was just a suggestion in response to a question I saw posted
in the archives. Ny needs are probably a bit different from the norm, so I
won't be using the suggested circuit. My needs are that the tower both lower
and raise automatically. In my case, there are a number of inputs to be
considered before acting. This will require a more complex setup.

Cranking the tower down while under a side load:
Since I am about to buy a motorized tower, it had better be able to be
safely cranked down with a load on it. I will make sure that the tower I
purchase has this capability - in writing.
I understand that some people in certain areas deal with continuous wind
loads. As such, the proposed device probably wouldn't be a good idea for
you. For Alabama, where the gust front before a thunderstorm is the norm,
you would need a relatively short sample period since you would be dealing
with gusts. In an area like Alabama, you would likely be lowering *without*
a side load, having detected a gust.

Vane type switch:
This is not a bad idea, but the "trip" range is fairly wide, so accuracy
will suffer. Also, these devices need to be perpendicular to the airflow. As
mentioned by K6SDW, you would need multiple switches. Unless you know which
way the wind is likely to blow, that would basically rule a single vane type
device out. There is a possibility that you could construct a wind vane to
point a single switch in the right direction.

RFI and the Davis Instrument weather station:
I was talking just about the vane/anemometer portion which is available
separately. I do have a couple of the Davis weather stations. Both are
wireless for the very same reason W2YR mentioned, RFI. I haven't had any RFI
problems with the wireless Davis systems as opposed to the wired ones.

Lowering hazards:
I agree with AD3F that there is some liability to moving anything
unattended. Much of my work has involved man/machine life and limb
situations. In this case, a fence is a good idea. I wouldn't think the
actual liability would be any worse than having a pool or the tower blowing
over on your neighbor's house.

Using a meteorological warning system:
I have a couple. Again, my goal was simplicity. If you are going to
automatically lower your tower with a computer, you are introducing
complexity. Besides, do you really want windows controlling your tower? I
certainly don't. In any case, if you want to see a an online weather system,
I have one online at http://www.dbtech.net/weather It even has a real time
lightning detection system.
The weather station is outside and operates wireless utilizing a solar cell
and battery. The lightning detector is in the attic.

If the weather is bad, just lower it:
That is good solid common sense. In my case, my tower will have a couple of
wireless data links in addition to my antennas. The tower needs to stay up
unless the weather is bad. It needs to lower automatically since it is often
unattended. The reasons I don't want a guyed tower are simple. Climbing
liability issues (and I don't want to climb it anyway) and tornados. Around
here the question isn't IF we will have a tornado, but WHEN. Seeing tall
structures bent around here is fairly common.

Using a controller such as a PIC:
Nothing wrong with that, but I don't see the need when a simple circuit will
do the job. If you have more demanding needs than just lowering on detection
of wind in excess of x speed, then the PIC might be a good choice. The PIC
*does* present a single chip solution if you are familiar with programming them.

Available power:
A good point that should be addressed by anyone with a motorized tower.
Not a problem here since I have an 80 kilowatt automatic backup generator,
but a  UPS sized to provide enough energy to lower your tower in an
emergency would be a good idea for anyone with weather issues. Weather
issues are the driving force behind the generator here. It is not uncommon
to see days without power. 
  
Circuit debounce:
Since debouncing is a function of time vs. input, I don't see the need since
a sample period is inherent in the design of the wind speed detector. If,
however, you wanted exceptional accuracy, then a debounce could kill some
potential noise introduced pulses.

All this is just my opinion, of course. I am sure many people on the list
feel that a crank-up or motorized crank-up tower is a waste of money and
time, as well as adding complexity to the issue. For my purposes, (and I
suspect for many others as well) a motorized tower fits my needs. Also,
automating any mechanical device is wrought with peril, *but*, it is doable.
If it weren't for automation, we would still be in the dark ages :-)

Thanks much for all the comments!

73,
David W4DLB


+++++++++++++++++++++++++++++++++++++
Sir, are you classified as human?
"Ah, negative. I am a meat popsicle"
+++++++++++++++++++++++++++++++++++++


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