Driver to drive?

[rickman]

On 10/30/2015 8:56 PM, Sylvia Else wrote:

On 31/10/2015 11:48 AM, Jim Thompson wrote:


I abhor microprocessors... the world is ANALOG O>:-}

I confess that my planned implementation includes a PIC. There are some
issues to be dealt with - people walking in front of the sensor,
intermittent sunlight due to clouds, and the rapid changes that occur as
the sun intersects the extended plane of the wall. No doubt these could
all be handled using analogue circuitry, but using a PIC will make life
simpler - particularly as I have much more experience with software than
I do electronics.

The sensor only needs to have a very slow response anyway, so why would
it respond to people walking in front of it? When clouds are in the way
both sensors will be shaded, so it shouldn't cause any problems. I'm
not sure what you mean be the sun intersecting the extended plane of the
wall. Do you mean self shading because the sun is blocked by the building?

--

Rick

 

[Jasen Betts]

On 2015-10-31, rickman <gnuarm@gmail.com> wrote:

On 10/30/2015 8:56 PM, Sylvia Else wrote:
On 31/10/2015 11:48 AM, Jim Thompson wrote:


I abhor microprocessors... the world is ANALOG O>:-}

I confess that my planned implementation includes a PIC. There are some
issues to be dealt with - people walking in front of the sensor,
intermittent sunlight due to clouds, and the rapid changes that occur as
the sun intersects the extended plane of the wall. No doubt these could
all be handled using analogue circuitry, but using a PIC will make life
simpler - particularly as I have much more experience with software than
I do electronics.

The sensor only needs to have a very slow response anyway, so why would
it respond to people walking in front of it? When clouds are in the way
both sensors will be shaded, so it shouldn't cause any problems. I'm
not sure what you mean be the sun intersecting the extended plane of the
wall. Do you mean self shading because the sun is blocked by the building?

maybe use something slower than LDRs, eg: thermistors.

--
\_(ツ)_

 

[Sylvia Else]

On 31/10/2015 6:08 PM, rickman wrote:

On 10/30/2015 8:56 PM, Sylvia Else wrote:
On 31/10/2015 11:48 AM, Jim Thompson wrote:


I abhor microprocessors... the world is ANALOG O>:-}

I confess that my planned implementation includes a PIC. There are some
issues to be dealt with - people walking in front of the sensor,
intermittent sunlight due to clouds, and the rapid changes that occur as
the sun intersects the extended plane of the wall. No doubt these could
all be handled using analogue circuitry, but using a PIC will make life
simpler - particularly as I have much more experience with software than
I do electronics.

The sensor only needs to have a very slow response anyway, so why would
it respond to people walking in front of it? When clouds are in the way
both sensors will be shaded, so it shouldn't cause any problems. I'm
not sure what you mean be the sun intersecting the extended plane of the
wall. Do you mean self shading because the sun is blocked by the building?

The sensor needs to be quick so that the awning extension will stop as
soon as the window is fully in shadow (plus a bit to prevent excessively
frequent movement).

As for the extended plane thing, just after the sun has moved to a
position where a wall is first illuminated, the shadows move very
quickly. I think the awning needs to be extended some distance
regardless of the sensor, again to avoid excessively frequent movement.

Sylvia.

 

[Andy Wood]

"Sylvia Else" wrote in message news:d9jnakFkgbiU1@mid.individual.net...
....

The sensor needs to be quick so that the awning extension will stop as soon
as the window is fully in shadow (plus a bit to prevent excessively
frequent movement).

I was wondering if you would have any control of the speed that the awning
moves, so I was looking at the sorts of things available. I notice that you
are re-inventing the wheel, because sun sensors (and wind sensors too) for
controlling awning motors are commercially available.

It would not surprise me if such sensors were expensive, or perhaps you just
relish the challenge of making your own. However, perhaps you could get some
ideas from a sensor made for the job?

 

[Ian Field]

"Trevor Wilson" <trevor@SPAMBLOCKrageaudio.com.au> wrote in message
news:d9gai3FoqgkU2@mid.individual.net...

On 29/10/2015 9:01 PM, o pere o wrote:
On 10/29/2015 09:25 AM, Sylvia Else wrote:
Adding sci.electronics.design, which got left out by mistake.

On 29/10/2015 5:41 PM, Sylvia Else wrote:

I want to make something to detect whether there's direct sunlight
shining on particular place. I thought the obvious approach would be to
use a pair of light dependent resistors (LDR) - one located where it
will definitely be in direct sunlight (when the sun is shining) and
another that is at the location to be tested. Compare the resistances,
and the result should be clear enough.

But this means that at least one LDR will be in direct sunlight for
extended periods, and I can find nothing in the datasheets to indicate
whether the devices will survive that. My concern is UV degradation of
the encapsulation material.

I can put them behind glass, which will provide some protection, but
even then, they'll have to survive some UV.

Anyone have experience of this?

Sylvia.


Perhaps you can use a small solar cell as the transducer? These should
survive direct sunlight during some decades.

Some time ago we even purchased a calibrated one, which could be used
for absolute measurements. I had a quick look but was unable to dig up
more details on it...

**Best idea.

Not least because the cadmium sulphide in an LDR doesn't sit well with RoHS.

Most countries comply with that even if it isn't in their own law, so they
can export to countries where it is.

Seems like most mainstream suppliers have dropped LDRs - I ordered a couple
of packets from China while I still could.

Cheap LDRs tend to be varnish coated, which is probably most likely to
degrade in UV. They used to be available in resin potted encapsulation,
which would probably be better.

There were TO5 metal cased type with a glass window that should be
completely immune - I think the last place I saw those listed, was the
company that makes Vactrols.

 

[Trevor Wilson]

On 1/11/2015 9:09 AM, Ian Field wrote:

"Trevor Wilson" <trevor@SPAMBLOCKrageaudio.com.au> wrote in message
news:d9gai3FoqgkU2@mid.individual.net...
On 29/10/2015 9:01 PM, o pere o wrote:
On 10/29/2015 09:25 AM, Sylvia Else wrote:
Adding sci.electronics.design, which got left out by mistake.

On 29/10/2015 5:41 PM, Sylvia Else wrote:

I want to make something to detect whether there's direct sunlight
shining on particular place. I thought the obvious approach would
be to
use a pair of light dependent resistors (LDR) - one located where it
will definitely be in direct sunlight (when the sun is shining) and
another that is at the location to be tested. Compare the resistances,
and the result should be clear enough.

But this means that at least one LDR will be in direct sunlight for
extended periods, and I can find nothing in the datasheets to indicate
whether the devices will survive that. My concern is UV degradation of
the encapsulation material.

I can put them behind glass, which will provide some protection, but
even then, they'll have to survive some UV.

Anyone have experience of this?

Sylvia.


Perhaps you can use a small solar cell as the transducer? These should
survive direct sunlight during some decades.

Some time ago we even purchased a calibrated one, which could be used
for absolute measurements. I had a quick look but was unable to dig up
more details on it...

**Best idea.

Not least because the cadmium sulphide in an LDR doesn't sit well with
RoHS.

**There is that, but I was thinking of the rapid degradation in an
outdoor situation. OTOH, small PV cells can be purchased, locally, for a
few Dollars (Bunnings), in the form of a nice, stainless steel encased,
garden lamp. I've had on in my garden for many years. Damned thing still
works (after a battery replacement). Cheap, reliable and available.

--
Trevor Wilson
www.rageaudio.com.au

 

[Sylvia Else]

On 1/11/2015 6:32 AM, Andy Wood wrote:

"Sylvia Else" wrote in message news:d9jnakFkgbiU1@mid.individual.net...
...
The sensor needs to be quick so that the awning extension will stop as
soon as the window is fully in shadow (plus a bit to prevent
excessively frequent movement).

I was wondering if you would have any control of the speed that the
awning moves, so I was looking at the sorts of things available. I
notice that you are re-inventing the wheel, because sun sensors (and
wind sensors too) for controlling awning motors are commercially available.

It would not surprise me if such sensors were expensive, or perhaps you
just relish the challenge of making your own. However, perhaps you could
get some ideas from a sensor made for the job?

Such examples as I've found just extend the awning to its end stop when
the sun is detected, and completely retract it when it's not. I want
something smarter than that.

Sylvia.

 

In sci.electronics.design krw <krw@nowhere.com> wrote:

On Fri, 30 Oct 2015 08:09:49 +0000 (UTC), mroberds@att.net wrote:

The air conditioning in my 2001 Toyota uses a sensor in the top of
the dash, near the bottom of the windshield, to determine how hard to
work; more sun = A/C works harder.

Our cars use those sensors for lighting control but I don't think the
HVAC is tied in. A thermostat would seem to work better.

Looking at the schematic for mine, the solar sensor goes straight into
the air conditioning ECU. That ECU also has two thermistors of its
own, one for the cabin temperature, and one for (I think) whatever the
heater or evaporator core is currently putting out. The schematic also
shows the engine ECU and its outdoor ambient thermistor, so I think it's
telling me that the air conditioner listens to that over the bus, too.

How I think it works is that it mostly uses the thermistors and the
desired temperature set by the user, like a thermostat, but that the
solar sensor changes the slope of the curve it uses to drive towards the
set point. It might also change the overshoot.

In other words, if you're 5 degrees F above the set point at night, it
will run the blower on "low", and stop when it is 1 degree F below the
set point. If you're 5 degrees F above the set point in the daytime, it
will run the blower on "high", and maybe wait until it is 2 or 3 F below
the set point to stop. The car company wants those MPG, but they also
don't want sweaty drivers.

Starting in about 2005, things got pretty chatty in a lot of cars... if
there's a sensor plugged into one ECU *anywhere*, most of the other ECUs
can get its value over the bus. By 2010, for sure. (This is partly
why Microsoft or Apple or Internet-connected anything, anywhere in the
car, scares me a lot.)

Matt Roberds

 

[Xeno]

On 1/11/2015 6:24 PM, mroberds@att.net wrote:

In sci.electronics.design krw <krw@nowhere.com> wrote:
On Fri, 30 Oct 2015 08:09:49 +0000 (UTC), mroberds@att.net wrote:

The air conditioning in my 2001 Toyota uses a sensor in the top of
the dash, near the bottom of the windshield, to determine how hard to
work; more sun = A/C works harder.

Our cars use those sensors for lighting control but I don't think the
HVAC is tied in. A thermostat would seem to work better.

Looking at the schematic for mine, the solar sensor goes straight into
the air conditioning ECU. That ECU also has two thermistors of its
own, one for the cabin temperature, and one for (I think) whatever the
heater or evaporator core is currently putting out. The schematic also
shows the engine ECU and its outdoor ambient thermistor, so I think it's
telling me that the air conditioner listens to that over the bus, too.

How I think it works is that it mostly uses the thermistors and the
desired temperature set by the user, like a thermostat, but that the
solar sensor changes the slope of the curve it uses to drive towards the
set point. It might also change the overshoot.

In other words, if you're 5 degrees F above the set point at night, it
will run the blower on "low", and stop when it is 1 degree F below the
set point. If you're 5 degrees F above the set point in the daytime, it
will run the blower on "high", and maybe wait until it is 2 or 3 F below
the set point to stop. The car company wants those MPG, but they also
don't want sweaty drivers.

Starting in about 2005, things got pretty chatty in a lot of cars... if
there's a sensor plugged into one ECU *anywhere*, most of the other ECUs
can get its value over the bus. By 2010, for sure. (This is partly
why Microsoft or Apple or Internet-connected anything, anywhere in the
car, scares me a lot.)

Matt Roberds

Microsoft having ANYTHING to to with car ECU programming has to be
dreaded! Can you imagine the 'Blue Screen Of Death' turning into an
ominous reality?

--

Xeno

 

[rickman]

On 10/31/2015 7:34 AM, Sylvia Else wrote:

On 31/10/2015 6:08 PM, rickman wrote:
On 10/30/2015 8:56 PM, Sylvia Else wrote:
On 31/10/2015 11:48 AM, Jim Thompson wrote:


I abhor microprocessors... the world is ANALOG O>:-}

I confess that my planned implementation includes a PIC. There are some
issues to be dealt with - people walking in front of the sensor,
intermittent sunlight due to clouds, and the rapid changes that occur as
the sun intersects the extended plane of the wall. No doubt these could
all be handled using analogue circuitry, but using a PIC will make life
simpler - particularly as I have much more experience with software than
I do electronics.

The sensor only needs to have a very slow response anyway, so why would
it respond to people walking in front of it? When clouds are in the way
both sensors will be shaded, so it shouldn't cause any problems. I'm
not sure what you mean be the sun intersecting the extended plane of the
wall. Do you mean self shading because the sun is blocked by the
building?


The sensor needs to be quick so that the awning extension will stop as
soon as the window is fully in shadow (plus a bit to prevent excessively
frequent movement).

You make it sound like the extension will be deployed from fully
retracted to some significant extension. If that is done, then yes,
fast reaction is needed, but once it finds it's position, it can operate
with a much slower response time.

As for the extended plane thing, just after the sun has moved to a
position where a wall is first illuminated, the shadows move very
quickly. I think the awning needs to be extended some distance
regardless of the sensor, again to avoid excessively frequent movement.

I'm still not picturing this, but that's ok.

--

Rick

 

[Sylvia Else]

On 1/11/2015 7:15 PM, rickman wrote:

On 10/31/2015 7:34 AM, Sylvia Else wrote:
On 31/10/2015 6:08 PM, rickman wrote:
On 10/30/2015 8:56 PM, Sylvia Else wrote:
On 31/10/2015 11:48 AM, Jim Thompson wrote:


I abhor microprocessors... the world is ANALOG O>:-}

I confess that my planned implementation includes a PIC. There are some
issues to be dealt with - people walking in front of the sensor,
intermittent sunlight due to clouds, and the rapid changes that
occur as
the sun intersects the extended plane of the wall. No doubt these could
all be handled using analogue circuitry, but using a PIC will make life
simpler - particularly as I have much more experience with software
than
I do electronics.

The sensor only needs to have a very slow response anyway, so why would
it respond to people walking in front of it? When clouds are in the way
both sensors will be shaded, so it shouldn't cause any problems. I'm
not sure what you mean be the sun intersecting the extended plane of the
wall. Do you mean self shading because the sun is blocked by the
building?


The sensor needs to be quick so that the awning extension will stop as
soon as the window is fully in shadow (plus a bit to prevent excessively
frequent movement).

You make it sound like the extension will be deployed from fully
retracted to some significant extension. If that is done, then yes,
fast reaction is needed, but once it finds it's position, it can operate
with a much slower response time.

It's not a one off. As the sun moves across the sky, the sensor will
again be exposed and the awning further extended.

Sylvia.

 

[krw]

On Sun, 1 Nov 2015 07:24:54 -0000 (UTC), mroberds@att.net wrote:

In sci.electronics.design krw <krw@nowhere.com> wrote:
On Fri, 30 Oct 2015 08:09:49 +0000 (UTC), mroberds@att.net wrote:

The air conditioning in my 2001 Toyota uses a sensor in the top of
the dash, near the bottom of the windshield, to determine how hard to
work; more sun = A/C works harder.

Our cars use those sensors for lighting control but I don't think the
HVAC is tied in. A thermostat would seem to work better.

Looking at the schematic for mine, the solar sensor goes straight into
the air conditioning ECU. That ECU also has two thermistors of its
own, one for the cabin temperature, and one for (I think) whatever the
heater or evaporator core is currently putting out. The schematic also
shows the engine ECU and its outdoor ambient thermistor, so I think it's
telling me that the air conditioner listens to that over the bus, too.

....or the AC ECU was simply a convenient place to connect the solar
sensor.

How I think it works is that it mostly uses the thermistors and the
desired temperature set by the user, like a thermostat, but that the
solar sensor changes the slope of the curve it uses to drive towards the
set point. It might also change the overshoot.

In other words, if you're 5 degrees F above the set point at night, it
will run the blower on "low", and stop when it is 1 degree F below the
set point. If you're 5 degrees F above the set point in the daytime, it
will run the blower on "high", and maybe wait until it is 2 or 3 F below
the set point to stop. The car company wants those MPG, but they also
don't want sweaty drivers.

Starting in about 2005, things got pretty chatty in a lot of cars... if
there's a sensor plugged into one ECU *anywhere*, most of the other ECUs
can get its value over the bus. By 2010, for sure. (This is partly
why Microsoft or Apple or Internet-connected anything, anywhere in the
car, scares me a lot.)

Matt Roberds

 

[krw]

On Sun, 1 Nov 2015 19:03:08 +1100, Xeno <xenolith@optusnet.com.au>
wrote:

On 1/11/2015 6:24 PM, mroberds@att.net wrote:
In sci.electronics.design krw <krw@nowhere.com> wrote:
On Fri, 30 Oct 2015 08:09:49 +0000 (UTC), mroberds@att.net wrote:

The air conditioning in my 2001 Toyota uses a sensor in the top of
the dash, near the bottom of the windshield, to determine how hard to
work; more sun = A/C works harder.

Our cars use those sensors for lighting control but I don't think the
HVAC is tied in. A thermostat would seem to work better.

Looking at the schematic for mine, the solar sensor goes straight into
the air conditioning ECU. That ECU also has two thermistors of its
own, one for the cabin temperature, and one for (I think) whatever the
heater or evaporator core is currently putting out. The schematic also
shows the engine ECU and its outdoor ambient thermistor, so I think it's
telling me that the air conditioner listens to that over the bus, too.

How I think it works is that it mostly uses the thermistors and the
desired temperature set by the user, like a thermostat, but that the
solar sensor changes the slope of the curve it uses to drive towards the
set point. It might also change the overshoot.

In other words, if you're 5 degrees F above the set point at night, it
will run the blower on "low", and stop when it is 1 degree F below the
set point. If you're 5 degrees F above the set point in the daytime, it
will run the blower on "high", and maybe wait until it is 2 or 3 F below
the set point to stop. The car company wants those MPG, but they also
don't want sweaty drivers.

Starting in about 2005, things got pretty chatty in a lot of cars... if
there's a sensor plugged into one ECU *anywhere*, most of the other ECUs
can get its value over the bus. By 2010, for sure. (This is partly
why Microsoft or Apple or Internet-connected anything, anywhere in the
car, scares me a lot.)

Matt Roberds

Microsoft having ANYTHING to to with car ECU programming has to be
dreaded! Can you imagine the 'Blue Screen Of Death' turning into an
ominous reality?

Microsoft did the Ford Sync-I software, and yes, it's a mess. It's
even kept lawyers employed.

 

[Ian Field]

"Trevor Wilson" <trevor@SPAMBLOCKrageaudio.com.au> wrote in message
news:d9kv61Fug3uU1@mid.individual.net...

On 1/11/2015 9:09 AM, Ian Field wrote:


"Trevor Wilson" <trevor@SPAMBLOCKrageaudio.com.au> wrote in message
news:d9gai3FoqgkU2@mid.individual.net...
On 29/10/2015 9:01 PM, o pere o wrote:
On 10/29/2015 09:25 AM, Sylvia Else wrote:
Adding sci.electronics.design, which got left out by mistake.

On 29/10/2015 5:41 PM, Sylvia Else wrote:

I want to make something to detect whether there's direct sunlight
shining on particular place. I thought the obvious approach would
be to
use a pair of light dependent resistors (LDR) - one located where it
will definitely be in direct sunlight (when the sun is shining) and
another that is at the location to be tested. Compare the
resistances,
and the result should be clear enough.

But this means that at least one LDR will be in direct sunlight for
extended periods, and I can find nothing in the datasheets to
indicate
whether the devices will survive that. My concern is UV degradation
of
the encapsulation material.

I can put them behind glass, which will provide some protection, but
even then, they'll have to survive some UV.

Anyone have experience of this?

Sylvia.


Perhaps you can use a small solar cell as the transducer? These should
survive direct sunlight during some decades.

Some time ago we even purchased a calibrated one, which could be used
for absolute measurements. I had a quick look but was unable to dig up
more details on it...

**Best idea.

Not least because the cadmium sulphide in an LDR doesn't sit well with
RoHS.


**There is that, but I was thinking of the rapid degradation in an outdoor
situation. OTOH, small PV cells can be purchased, locally, for a few
Dollars (Bunnings), in the form of a nice, stainless steel encased, garden
lamp. I've had on in my garden for many years. Damned thing still works
(after a battery replacement). Cheap, reliable and available.

If the OP is set on using a LDR, it may still be possible to get hold of the
TO5 with glass window that I mentioned but you snipped.

But with everything else considered, I agree that a solar cell is the better
option.

 

[rickman]

On 11/1/2015 3:26 AM, Sylvia Else wrote:

On 1/11/2015 7:15 PM, rickman wrote:
On 10/31/2015 7:34 AM, Sylvia Else wrote:
On 31/10/2015 6:08 PM, rickman wrote:
On 10/30/2015 8:56 PM, Sylvia Else wrote:
On 31/10/2015 11:48 AM, Jim Thompson wrote:


I abhor microprocessors... the world is ANALOG O>:-}

I confess that my planned implementation includes a PIC. There are
some
issues to be dealt with - people walking in front of the sensor,
intermittent sunlight due to clouds, and the rapid changes that
occur as
the sun intersects the extended plane of the wall. No doubt these
could
all be handled using analogue circuitry, but using a PIC will make
life
simpler - particularly as I have much more experience with software
than
I do electronics.

The sensor only needs to have a very slow response anyway, so why would
it respond to people walking in front of it? When clouds are in the
way
both sensors will be shaded, so it shouldn't cause any problems. I'm
not sure what you mean be the sun intersecting the extended plane of
the
wall. Do you mean self shading because the sun is blocked by the
building?


The sensor needs to be quick so that the awning extension will stop as
soon as the window is fully in shadow (plus a bit to prevent excessively
frequent movement).

You make it sound like the extension will be deployed from fully
retracted to some significant extension. If that is done, then yes,
fast reaction is needed, but once it finds it's position, it can operate
with a much slower response time.

It's not a one off. As the sun moves across the sky, the sensor will
again be exposed and the awning further extended.

I'm not clear what you are saying. Of course it will have to adjust
multiple times during the day. But the movement does not need to be
anything remotely fast, so the sensor does not need to be quick
responding. Even if the awning has a little overshoot, that just means
it will be a little while longer before it adjusts again. Any control
system will have overshoot and a lag in response. The only issue is how
much is acceptable and how much is too much.

I can't imagine the shadow of a passing bird or a person walking by
would have to upset a device like this that is tracking the movement of
the sun.

--

Rick

 

[krw]

On Sun, 1 Nov 2015 12:56:32 -0500, rickman <gnuarm@gmail.com> wrote:

On 11/1/2015 3:26 AM, Sylvia Else wrote:
On 1/11/2015 7:15 PM, rickman wrote:
On 10/31/2015 7:34 AM, Sylvia Else wrote:
On 31/10/2015 6:08 PM, rickman wrote:
On 10/30/2015 8:56 PM, Sylvia Else wrote:
On 31/10/2015 11:48 AM, Jim Thompson wrote:


I abhor microprocessors... the world is ANALOG O>:-}

I confess that my planned implementation includes a PIC. There are
some
issues to be dealt with - people walking in front of the sensor,
intermittent sunlight due to clouds, and the rapid changes that
occur as
the sun intersects the extended plane of the wall. No doubt these
could
all be handled using analogue circuitry, but using a PIC will make
life
simpler - particularly as I have much more experience with software
than
I do electronics.

The sensor only needs to have a very slow response anyway, so why would
it respond to people walking in front of it? When clouds are in the
way
both sensors will be shaded, so it shouldn't cause any problems. I'm
not sure what you mean be the sun intersecting the extended plane of
the
wall. Do you mean self shading because the sun is blocked by the
building?


The sensor needs to be quick so that the awning extension will stop as
soon as the window is fully in shadow (plus a bit to prevent excessively
frequent movement).

You make it sound like the extension will be deployed from fully
retracted to some significant extension. If that is done, then yes,
fast reaction is needed, but once it finds it's position, it can operate
with a much slower response time.

It's not a one off. As the sun moves across the sky, the sensor will
again be exposed and the awning further extended.

I'm not clear what you are saying. Of course it will have to adjust
multiple times during the day. But the movement does not need to be
anything remotely fast, so the sensor does not need to be quick
responding. Even if the awning has a little overshoot, that just means
it will be a little while longer before it adjusts again. Any control
system will have overshoot and a lag in response. The only issue is how
much is acceptable and how much is too much.

I can't imagine the shadow of a passing bird or a person walking by
would have to upset a device like this that is tracking the movement of
the sun.

Why does it have to track the sun? Put the sensor at the bottom of
the window. If it's in the sun, extend the awning until it isn't.

 

[Sylvia Else]

On 2/11/2015 4:56 AM, rickman wrote:

On 11/1/2015 3:26 AM, Sylvia Else wrote:
On 1/11/2015 7:15 PM, rickman wrote:
On 10/31/2015 7:34 AM, Sylvia Else wrote:
On 31/10/2015 6:08 PM, rickman wrote:
On 10/30/2015 8:56 PM, Sylvia Else wrote:
On 31/10/2015 11:48 AM, Jim Thompson wrote:


I abhor microprocessors... the world is ANALOG O>:-}

I confess that my planned implementation includes a PIC. There are
some
issues to be dealt with - people walking in front of the sensor,
intermittent sunlight due to clouds, and the rapid changes that
occur as
the sun intersects the extended plane of the wall. No doubt these
could
all be handled using analogue circuitry, but using a PIC will make
life
simpler - particularly as I have much more experience with software
than
I do electronics.

The sensor only needs to have a very slow response anyway, so why
would
it respond to people walking in front of it? When clouds are in the
way
both sensors will be shaded, so it shouldn't cause any problems. I'm
not sure what you mean be the sun intersecting the extended plane of
the
wall. Do you mean self shading because the sun is blocked by the
building?


The sensor needs to be quick so that the awning extension will stop as
soon as the window is fully in shadow (plus a bit to prevent
excessively
frequent movement).

You make it sound like the extension will be deployed from fully
retracted to some significant extension. If that is done, then yes,
fast reaction is needed, but once it finds it's position, it can operate
with a much slower response time.

It's not a one off. As the sun moves across the sky, the sensor will
again be exposed and the awning further extended.

I'm not clear what you are saying. Of course it will have to adjust
multiple times during the day. But the movement does not need to be
anything remotely fast, so the sensor does not need to be quick
responding. Even if the awning has a little overshoot, that just means
it will be a little while longer before it adjusts again. Any control
system will have overshoot and a lag in response. The only issue is how
much is acceptable and how much is too much.

Commercially available awning motors are not variable speed. Short of
modifying one or building one from scratch, I appear to have no way of
achieving slow awning movement. I have to work with what I can get.

Sylvia.

 

[rickman]

On 11/1/2015 7:39 PM, Sylvia Else wrote:

On 2/11/2015 4:56 AM, rickman wrote:
On 11/1/2015 3:26 AM, Sylvia Else wrote:
On 1/11/2015 7:15 PM, rickman wrote:
On 10/31/2015 7:34 AM, Sylvia Else wrote:
On 31/10/2015 6:08 PM, rickman wrote:
On 10/30/2015 8:56 PM, Sylvia Else wrote:
On 31/10/2015 11:48 AM, Jim Thompson wrote:


I abhor microprocessors... the world is ANALOG O>:-}

I confess that my planned implementation includes a PIC. There are
some
issues to be dealt with - people walking in front of the sensor,
intermittent sunlight due to clouds, and the rapid changes that
occur as
the sun intersects the extended plane of the wall. No doubt these
could
all be handled using analogue circuitry, but using a PIC will make
life
simpler - particularly as I have much more experience with software
than
I do electronics.

The sensor only needs to have a very slow response anyway, so why
would
it respond to people walking in front of it? When clouds are in the
way
both sensors will be shaded, so it shouldn't cause any problems. I'm
not sure what you mean be the sun intersecting the extended plane of
the
wall. Do you mean self shading because the sun is blocked by the
building?


The sensor needs to be quick so that the awning extension will stop as
soon as the window is fully in shadow (plus a bit to prevent
excessively
frequent movement).

You make it sound like the extension will be deployed from fully
retracted to some significant extension. If that is done, then yes,
fast reaction is needed, but once it finds it's position, it can
operate
with a much slower response time.

It's not a one off. As the sun moves across the sky, the sensor will
again be exposed and the awning further extended.

I'm not clear what you are saying. Of course it will have to adjust
multiple times during the day. But the movement does not need to be
anything remotely fast, so the sensor does not need to be quick
responding. Even if the awning has a little overshoot, that just means
it will be a little while longer before it adjusts again. Any control
system will have overshoot and a lag in response. The only issue is how
much is acceptable and how much is too much.

Commercially available awning motors are not variable speed. Short of
modifying one or building one from scratch, I appear to have no way of
achieving slow awning movement. I have to work with what I can get.

They are fast? Then I guess you need a fast response when in motion,
slow the rest of the time.

--

Rick

 

[Joe Hey]

On Mon, 2 Nov 2015 11:39:44 +1100
Sylvia Else <sylvia@not.at.this.address> wrote:

}snip{

Commercially available awning motors are not variable speed. Short of
modifying one or building one from scratch, I appear to have no way
of achieving slow awning movement. I have to work with what I can get.

How about intermittent adjustment?
Let's say every hour (or 30 minutes or whatever you prefer) you switch
on the tracker. It awns, maybe incredibly fast, and then it stops.
After your preferred time window it tracks again.

joe

Sylvia.

 

On Sat, 31 Oct 2015 01:20:35 -0500, John S <Sophi.2@invalid.org>
wrote:

On 10/29/2015 3:25 AM, Sylvia Else wrote:
Adding sci.electronics.design, which got left out by mistake.

On 29/10/2015 5:41 PM, Sylvia Else wrote:

I want to make something to detect whether there's direct sunlight
shining on particular place. I thought the obvious approach would be to
use a pair of light dependent resistors (LDR) - one located where it
will definitely be in direct sunlight (when the sun is shining) and
another that is at the location to be tested. Compare the resistances,
and the result should be clear enough.

But this means that at least one LDR will be in direct sunlight for
extended periods, and I can find nothing in the datasheets to indicate
whether the devices will survive that. My concern is UV degradation of
the encapsulation material.

I can put them behind glass, which will provide some protection, but
even then, they'll have to survive some UV.

Anyone have experience of this?

Sylvia.


How about using an IR-transparent filter in front of the sensors?

The usual thing they use to measure solar energy is a Pyranometer.

https://en.wikipedia.org/wiki/Pyranometer


For whatever time of the year and the typical irradiance when no
clouds are present at your latitude, this will tell you what you've
got shining down on it.

boB