RadioBanter - Antenna rotator

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I am wondering if anyone has managed to convert/use a standard antenna
rotator for tracking purposes? I know that very expensive antenna rotators
are available for this use but hey there is no fun or challenge in that!

Want to use it to automate tracking the sun - have two solar panels mounted
on one, currently using manual control.

If you want to see what I am talking about here is a link to the picture (
bottom one) of what I am using.

http://www.flightsimulatorandhobbies.com/solar.htm

-----------------------------------------
You have hobbies. I have hobbies.
Chances are I have one that you don't.
I'll leave it up to you to decide!
http://www.flightsimulatorandhobbies.com/
-----------------------------------------

"JERD" wrote in message
...
I am wondering if anyone has managed to convert/use a standard antenna
rotator for tracking purposes? I know that very expensive antenna rotators
are available for this use but hey there is no fun or challenge in that!

Want to use it to automate tracking the sun - have two solar panels
mounted
on one, currently using manual control.

I invented such a thing in my head but have never built it. My idea could
be adapted to what you already have. It is quite difficult to describe
without diagrams, but I'll give it a shot.

Imagine that your rotator is reset by you each sunny morning, pointing east
at the rising sun. You flip a TRANSFER switch and westward rotator power
is then applied through the contacts of a normally-closed (NC) relay . At
that moment, however, the relay is held open with coil current provided by
the amplified signal of a photosensor which is collocated with the collector
panels. It is aimed in the same direction as the panels, but it has
blinders on it so it has only a narrow field of view in the east-west
direction. Thus, the photosensor is illuminated because it is pointing in
the direction of the sun. First thing in the morning, with the panels and
the photosensor pointing at the sun, nothing happens when you throw the
TRANSFER switch.

But wait ...
As the sun rises, it gradually moves to a point where it is NOT illuminating
the photosensor. The relay drops and energizes the rotator. The rotator
moves but an instant later, the whole rig is again aimed at the sun, which
illuminates the photosensor. The relay re-energizes, removing power from
the rotator and movement stops. This process might repeat ten or twenty
times a day, depending on the angle of view of the photosensor.

For the fans of disclaimers, let me say I fully realize the relay could be
of the normally open (NO) variety and be pulled closed when the sensor is in
shade. (I had to pick one possibility for the description.) Photosensor
means any one of several types of light-to-electricity transducers. Relays
have solid-state alternatives. The TRANSFER switch is a minor
modification of the rotator control box he's probably using now.

Clouds will louse this up. With no sunshine, the tracking process should be
halted; thus, the circuit requires the addition of an all-seeing photosensor
(no blinders) to test whether the sun is shining and interrupt the power if
it's not.

This is hardly the only autotracker design that would work and you could
even add elevation tracking.(However, in addition to all the mechanical
things, elevation tracking control would require at least another pair of
sensors and possibly a lens system rather than simple blinders. Probably
too hard.)

Automatic daily resetting could be accomplished with a dedicated
sunrise-sensing photosensor and additional modification of the control box.
This would enable you to sleep in. (You could involve the "all-seeing
photosensor," above, in this, but the logic would have to include a test for
the approximate time-of day, so the daily reset could happen only in the
morning.)

Lest anybody be concerned this has nothing to do with antennas, let me
hasten to state that my last unconventional use for an antenna rotator was
to make a true tracking polar mount for a Ku-band satellite dish. Looks
like crap but tracks the arc perfectly. So there is a tenuous connection.

"Sal"

Imagine that your rotator is reset by you each sunny morning, pointing
east
at the rising sun. You flip a TRANSFER switch and westward rotator
power
is then applied through the contacts of a normally-closed (NC) relay . At
that moment, however, the relay is held open with coil current provided by
the amplified signal of a photosensor which is collocated with the
collector
panels. It is aimed in the same direction as the panels, but it has
blinders on it so it has only a narrow field of view in the east-west
direction. Thus, the photosensor is illuminated because it is pointing in
the direction of the sun. First thing in the morning, with the panels and
the photosensor pointing at the sun, nothing happens when you throw the
TRANSFER switch.

But wait ...
As the sun rises, it gradually moves to a point where it is NOT
illuminating
the photosensor. The relay drops and energizes the rotator. The rotator
moves but an instant later, the whole rig is again aimed at the sun, which
illuminates the photosensor. The relay re-energizes, removing power from
the rotator and movement stops. This process might repeat ten or twenty
times a day, depending on the angle of view of the photosensor.

Surely it is much simpler than that, as long as you are only interested in
azimuth and not elevation. The trouble with photo-sensors and the like is
that there will be a problem when the sun is behind cloud, and that will
cause all sorts of 'hunting' problems.

The good thing about the sun is that you always know where it will be at any
time of the day, and the rate at which it moves, so all you have to do is
arrange a mechanism that rotates by 15 degrees an hour. If you are only
pointing solar panels the you could step in at say 15 or 30 minute
intervals, rather than have it continuously tracking.

73
Jeff

Likewise only a thought experiment from this end.

I favour using an old PC running Linux and whatever I/O cards are
available for the purpose. If you network the device into the ROW you
will have time of day and if you need the accuracy, the actual sun
motion numbers.

You can also use a old DOS version as that allows direct access to ports
using debug. (Finally found a use for a 286! I use to have one moving a
stepper motor ez-al array some years ago. Used 3 bits each axis from the
printer port)

From memory most rotators have a pot feedback that determines where it
is pointed. This means you need some kind of analogue input to the PC. A
joy stick port maybe? Don't forget that a sound card input could also be
used once you remove the AC coupling capacitor to its A/D.

So after calibrating the system for azimuth vs input volts you have a
lookup table that you can base your command on. You can use serial or
parallel port pins to actuate the motor.

Problem of course is that the PC uses a considerable amount of the
energy gained from the array just to run itself! You could of course
automatically sleep and wake it every 30 minutes or so!

Another possibility - Your rotator controller either has a direct
feedback to a position knob or a display and CW/CCW switch? Should be
pretty easy to use the feedback knob/display meter volts/comparator to
actuate the drive. Just create an analogue lookup table with a simple
4-8 bit TTL/CMOS counter and a stack of resistors and you are away! It
would even reset itself for the start of the new day. Only real problem
is where you source the counter clock from.

Cheers Bob VK2YQA

JERD wrote:
I am wondering if anyone has managed to convert/use a standard antenna
rotator for tracking purposes? I know that very expensive antenna rotators
are available for this use but hey there is no fun or challenge in that!

"Jeff" wrote in message
. com...
The trouble with photo-sensors and the like is
that there will be a problem when the sun is behind cloud, and that will
cause all sorts of 'hunting' problems.

No, there won't be hunting. First, there is one photsensor that has no
blinders. It senses the presence of sun -- anywhere. When a cloud obscures
the sun, it inhibits tracking.

Second, the tracker only goes in one direction, advancing ever-westward,
automatically following the sun by steps, assuming a sunny day. Recall, I
said the shining of the sun onto the photosensor is what stops the advance
and the loss of sunshine onto the sensor restarts the advance.

The good thing about the sun is that you always know where it will be at
any
time of the day, and the rate at which it moves, so all you have to do is
arrange a mechanism that rotates by 15 degrees an hour.

Describe your mechanism. Making the version I originally described requires
only two photosensors, a dual DC amplifier chip, two relay driver modules,
two relays, a switch, a small prototyping board and some wire.

"JERD" wrote in news:bgt0j.14841$CN4.8264
@news-server.bigpond.net.au:

http://www.flightsimulatorandhobbies.com/solar.htm

It doesn't seem that you have any adjustment of the elevation, and that you
are just going to drive the azimuth.

If that is the case, why not just drive it from a clock, ie the azimuth
angle calculated or looked up from hour of day.

BTW, this is hardly an optimised pointing.

You comment about 15°/hr is applicable to an hour angle / declination
mount... but that isn't what is in the picture.

Owen

that there will be a problem when the sun is behind cloud, and that will
cause all sorts of 'hunting' problems.

No, there won't be hunting. First, there is one photsensor that has no
blinders. It senses the presence of sun -- anywhere. When a cloud
obscures
the sun, it inhibits tracking.

Second, the tracker only goes in one direction, advancing ever-westward,
automatically following the sun by steps, assuming a sunny day. Recall, I
said the shining of the sun onto the photosensor is what stops the advance
and the loss of sunshine onto the sensor restarts the advance.

The system works unitil it gets out of sync for some reason. A leaf
obscuring a sensor, a bird sitting on it etc etc.
One the rotator gets ahead of itself it will never find the sun.

The good thing about the sun is that you always know where it will be at
any
time of the day, and the rate at which it moves, so all you have to do is
arrange a mechanism that rotates by 15 degrees an hour.

Describe your mechanism. Making the version I originally described
requires
only two photosensors, a dual DC amplifier chip, two relay driver modules,
two relays, a switch, a small prototyping board and some wire.

The actual system will depend on what type of rotator you are using, a
stepper motor would be the easiest since you know how many degrees each step
is. If you are using an 'normal' antenna' rotator then most have a feedback
pot, and a control pot. All you have to do is apply a voltage in place of
the control pot to get your desired position. There are many ways of doing
that from a computer, a micro controller, a counter chip feeding a d/a
converter. a series of relays switching in resistors, the list is almost
endless.

73
Jeff

"Jeff" wrote in message
. com...

snip

The system works unitil it gets out of sync for some reason. A leaf
obscuring a sensor, a bird sitting on it etc etc.
One the rotator gets ahead of itself it will never find the sun.

This is true.Perhaps multiple sensors to some OR gates would provide the
necessary redundancy. I provided only one fail-safe mechanism and that is
for a cloud.

snip

The actual system will depend on what type of rotator you are using, a
stepper motor would be the easiest since you know how many degrees each
step
is. If you are using an 'normal' antenna' rotator then most have a
feedback
pot, and a control pot. All you have to do is apply a voltage in place of
the control pot to get your desired position. There are many ways of doing
that from a computer, a micro controller, a counter chip feeding a d/a
converter. a series of relays switching in resistors, the list is almost
endless.

What, no hamsters? :-)

Seriously, OP "JERD" never said whether he wanted a complicated, highly
accurate setup or just something that works. I went for bare-bones, basic
El Cheapo, the most fun, IMHO.

(I have more of a history of jury rigging antenna rotators than most people.
My first [1968] was the building of a controller based on two doorbell
pushbuttons from the hardware store; I bought the correct transformer and
capacitor from the electronics store. No indicator ... We aimed it solely
by looking at the TV. The components were screwed down to a chunk of
plywood I found in the yard. Oy! But I was a young sailor living in town
on my own dime for the first time. After rent and utilities, there was beer
money and not much else.)

73
"Sal"

On Nov 20, 3:41 am, "Sal M. Onella"
wrote:
"JERD" wrote in message

.. . . . . .
have solid-state alternatives. The TRANSFER switch is a minor
modification of the rotator control box he's probably using now.

Clouds will louse this up.

Use an infrared sensor.

"Sal"

w3rv

"Brian Kelly" wrote in message
...
On Nov 20, 3:41 am, "Sal M. Onella"
wrote:
"JERD" wrote in message

. . . . . .
have solid-state alternatives. The TRANSFER switch is a minor
modification of the rotator control box he's probably using now.

Clouds will louse this up.

Use an infrared sensor.

"Sal"

Or U/V, maybe. No wonder we enjoy so much good stuff -- there is no end to
the ingenuity. Thanks, Brian.

BTW, I don't see the OP back in here. He may be out buying photosensors and
relays. Ya' think?