Driver to drive?

Nov 4, 2015

ĺ¨ 2002ĺš´2ć14ćĽććĺ UTC+8ä¸ĺ2:46:53ďźJim Drewĺéďź

I have a project that uses a small DC electric motor, powered by a 0-9v
source and can draw up to 1 amp of current.

I need a way to convert the current draw (0-1 amp) into a voltage (0 to
5v). I need 0-5v so that I can feed it a microcontroller's A/D
converter.

I realize that I need an op-amp and a super low value resistor, but I am
confused about turning 0-9v based current into proportional 0-5v
voltage. Anyone have a simple schematic that will work for this
application?

Thanks!

Sell:
China Shenzhen ZHAOWEI Machinery & Electronics Co. Ltd engages in designing, manufacturing and marketing all kinds of electric motors. They are mainly suitable for the following applications: smart home application used in smart kitchen and laundry, medical instrument for personal care, smart E-transmission applied in automobile, industry automation applied in telecommunication and a great variety of plastic/metal planetary gearbox in different sizes.
In order to develop the oversea market, we are current seeking new partners around the world to create a bright future together. ZhaoWei is a right choice and excellent partnership with sincere services.

Company: Shenzhen ZHAOWEI Machinery & Electronics Co., Ltd
URL: http://www.zwgearbox.com/
Contact: Anny Liu
Telďź+86-755-27322652
Faxďź+86-755-27323949
E-mail:sales@zwgearbox.com
Add: Blk. 18, Longwangmiao Industry Park, Fuyong Tn., Baoâan Dist., Shenzhen 518103, Guangdong, China

Jim Thompson · Nov 4, 2015

On Sat, 31 Oct 2015 11:56:40 +1100, Sylvia Else
<sylvia@not.at.this.address> 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.

Sylvia.

Nov 5, 2015

Sell:
China Shenzhen ZHAOWEI Machinery & Electronics Co. Ltd engages in designing, manufacturing and marketing all kinds of electric motors. They are mainly suitable for the following applications: smart home application used in smart kitchen and laundry, medical instrument for personal care, smart E-transmission applied in automobile, industry automation applied in telecommunication and a great variety of plastic/metal planetary gearbox in different sizes.
In order to develop the oversea market, we are current seeking new partners around the world to create a bright future together. ZhaoWei is a right choice and excellent partnership with sincere services.

Company: Shenzhen ZHAOWEI Machinery & Electronics Co., Ltd
URL: http://www.zwgearbox.com/
Contact: Anny Liu
Telďź+86-755-27322652
Faxďź+86-755-27323949
E-mail:sales@zwgearbox.com
Add: Blk. 18, Longwangmiao Industry Park, Fuyong Tn., Baoâan Dist., Shenzhen 518103, Guangdong, China

Sylvia Else · Nov 5, 2015

On 5/11/2015 2:23 AM, Jim Thompson wrote:

On Sat, 31 Oct 2015 11:56:40 +1100, Sylvia Else
sylvia@not.at.this.address> 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.

Sylvia.

It struck me this morning that all you need to do is sense the
elevation angle of the sun... half of a typical sun-follower sensor,
then use your PIC to adjust the awning.

...Jim Thompson

I can't accurately position the awning, since I haven't found an awning
motor that gives position feedback (or any feedback, come to that).
There are some for roller blinds, but they're for indoor use only.

I'd have to implement something to sense the awning position, and that
seems likely to work out even more complicated than sensing when the
awning puts the bottom of the widow into shadow.

Sylvia.

Jim Thompson · Nov 5, 2015

On Thu, 5 Nov 2015 19:45:41 +1100, Sylvia Else
<sylvia@not.at.this.address> wrote:

On 5/11/2015 2:23 AM, Jim Thompson wrote:
On Sat, 31 Oct 2015 11:56:40 +1100, Sylvia Else
sylvia@not.at.this.address> 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.

Sylvia.

It struck me this morning that all you need to do is sense the
elevation angle of the sun... half of a typical sun-follower sensor,
then use your PIC to adjust the awning.

...Jim Thompson

I can't accurately position the awning, since I haven't found an awning
motor that gives position feedback (or any feedback, come to that).
There are some for roller blinds, but they're for indoor use only.

I'd have to implement something to sense the awning position, and that
seems likely to work out even more complicated than sensing when the
awning puts the bottom of the widow into shadow.

Sylvia.

Lasse Langwadt Christense · Nov 6, 2015

Den fredag den 6. november 2015 kl. 01.10.17 UTC+1 skrev Sylvia Else:

On 6/11/2015 1:51 AM, Jim Thompson wrote:
On Thu, 5 Nov 2015 19:45:41 +1100, Sylvia Else
sylvia@not.at.this.address> wrote:

On 5/11/2015 2:23 AM, Jim Thompson wrote:
On Sat, 31 Oct 2015 11:56:40 +1100, Sylvia Else
sylvia@not.at.this.address> 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.

Sylvia.

It struck me this morning that all you need to do is sense the
elevation angle of the sun... half of a typical sun-follower sensor,
then use your PIC to adjust the awning.

...Jim Thompson

I can't accurately position the awning, since I haven't found an awning
motor that gives position feedback (or any feedback, come to that).
There are some for roller blinds, but they're for indoor use only.

I'd have to implement something to sense the awning position, and that
seems likely to work out even more complicated than sensing when the
awning puts the bottom of the widow into shadow.

Sylvia.

Can you describe the awning and its mechanism?

...Jim Thompson

This is a typical pivot arm awning.

http://www.supaview.com.au/wp-content/uploads/2013/06/Mesh-Drop-Arm-Awning.jpg

At the top there is a cylinder, onto which the fabric is rolled as the
awning is pulled up. The arm pivots on a bearing that is fixed to the
wall, with the other end being attached to a fixed position on the
awning. So, as the awning is extended, the lower end of the awning
describes a semicircle centred on the pivot bearing.

The motor fits inside one end of the cylinder. Here is a typical example:

https://www.somfy.co.uk/common/img/library//332x332/SUNEA_50_IO1.jpg

So the options I can think of are

a) Measure the angular position of the cylinder.

b) Paint a Gray code onto the fabric, and use an optical sensor to track
how much is extended.

c) Measure the angular position of the pivot arm.

d) Get the motor to report the angular position of the cylinder.

As I've said, some motors will do (d) for interior roller blinds, but
I've not found such a capability in exterior awning motors.

Option (b) has both cosmetic and longevity issues.

Option (a) might be feasible if enough of the cylinder remains exposed
at all times, and depending on how the top of the awning is enclosed.

Not sure about option (c).

Sylvia.

stick a magnet on the cylinder and use a hall sensor to count when you are

-Lasse

Sylvia Else · Nov 6, 2015

On 6/11/2015 1:51 AM, Jim Thompson wrote:

On Thu, 5 Nov 2015 19:45:41 +1100, Sylvia Else
sylvia@not.at.this.address> wrote:

On 5/11/2015 2:23 AM, Jim Thompson wrote:
On Sat, 31 Oct 2015 11:56:40 +1100, Sylvia Else
sylvia@not.at.this.address> 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.

Sylvia.

It struck me this morning that all you need to do is sense the
elevation angle of the sun... half of a typical sun-follower sensor,
then use your PIC to adjust the awning.

...Jim Thompson

I can't accurately position the awning, since I haven't found an awning
motor that gives position feedback (or any feedback, come to that).
There are some for roller blinds, but they're for indoor use only.

I'd have to implement something to sense the awning position, and that
seems likely to work out even more complicated than sensing when the
awning puts the bottom of the widow into shadow.

Sylvia.

Can you describe the awning and its mechanism?

...Jim Thompson

This is a typical pivot arm awning.

<http://www.supaview.com.au/wp-content/uploads/2013/06/Mesh-Drop-Arm-Awning.jpg>

At the top there is a cylinder, onto which the fabric is rolled as the
awning is pulled up. The arm pivots on a bearing that is fixed to the
wall, with the other end being attached to a fixed position on the
awning. So, as the awning is extended, the lower end of the awning
describes a semicircle centred on the pivot bearing.

The motor fits inside one end of the cylinder. Here is a typical example:

https://www.somfy.co.uk/common/img/library//332x332/SUNEA_50_IO1.jpg

So the options I can think of are

a) Measure the angular position of the cylinder.

b) Paint a Gray code onto the fabric, and use an optical sensor to track
how much is extended.

c) Measure the angular position of the pivot arm.

d) Get the motor to report the angular position of the cylinder.

As I've said, some motors will do (d) for interior roller blinds, but
I've not found such a capability in exterior awning motors.

Option (b) has both cosmetic and longevity issues.

Option (a) might be feasible if enough of the cylinder remains exposed
at all times, and depending on how the top of the awning is enclosed.

Not sure about option (c).

Sylvia.

Xeno · Nov 6, 2015

On 6/11/2015 11:10 AM, Sylvia Else wrote:

On 6/11/2015 1:51 AM, Jim Thompson wrote:
On Thu, 5 Nov 2015 19:45:41 +1100, Sylvia Else
sylvia@not.at.this.address> wrote:

On 5/11/2015 2:23 AM, Jim Thompson wrote:
On Sat, 31 Oct 2015 11:56:40 +1100, Sylvia Else
sylvia@not.at.this.address> 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.

Sylvia.

It struck me this morning that all you need to do is sense the
elevation angle of the sun... half of a typical sun-follower sensor,
then use your PIC to adjust the awning.

...Jim Thompson

I can't accurately position the awning, since I haven't found an awning
motor that gives position feedback (or any feedback, come to that).
There are some for roller blinds, but they're for indoor use only.

I'd have to implement something to sense the awning position, and that
seems likely to work out even more complicated than sensing when the
awning puts the bottom of the widow into shadow.

Sylvia.

Can you describe the awning and its mechanism?

...Jim Thompson

This is a typical pivot arm awning.

http://www.supaview.com.au/wp-content/uploads/2013/06/Mesh-Drop-Arm-Awning.jpg

At the top there is a cylinder, onto which the fabric is rolled as the
awning is pulled up. The arm pivots on a bearing that is fixed to the
wall, with the other end being attached to a fixed position on the
awning. So, as the awning is extended, the lower end of the awning
describes a semicircle centred on the pivot bearing.

The motor fits inside one end of the cylinder. Here is a typical example:

https://www.somfy.co.uk/common/img/library//332x332/SUNEA_50_IO1.jpg

So the options I can think of are

a) Measure the angular position of the cylinder.

b) Paint a Gray code onto the fabric, and use an optical sensor to track
how much is extended.

c) Measure the angular position of the pivot arm.

d) Get the motor to report the angular position of the cylinder.

As I've said, some motors will do (d) for interior roller blinds, but
I've not found such a capability in exterior awning motors.

Option (b) has both cosmetic and longevity issues.

Option (a) might be feasible if enough of the cylinder remains exposed
at all times, and depending on how the top of the awning is enclosed.

Not sure about option (c).

Sylvia.

Option C looks like your best bet. Option D might be problematic given
that the blind will require multiple turns of the motor to extend the
awning.

--

Xeno

rickman · Nov 6, 2015

On 11/5/2015 7:10 PM, Sylvia Else wrote:

On 6/11/2015 1:51 AM, Jim Thompson wrote:
On Thu, 5 Nov 2015 19:45:41 +1100, Sylvia Else
sylvia@not.at.this.address> wrote:

On 5/11/2015 2:23 AM, Jim Thompson wrote:
On Sat, 31 Oct 2015 11:56:40 +1100, Sylvia Else
sylvia@not.at.this.address> 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.

Sylvia.

It struck me this morning that all you need to do is sense the
elevation angle of the sun... half of a typical sun-follower sensor,
then use your PIC to adjust the awning.

...Jim Thompson

I can't accurately position the awning, since I haven't found an awning
motor that gives position feedback (or any feedback, come to that).
There are some for roller blinds, but they're for indoor use only.

I'd have to implement something to sense the awning position, and that
seems likely to work out even more complicated than sensing when the
awning puts the bottom of the widow into shadow.

Sylvia.

Can you describe the awning and its mechanism?

...Jim Thompson

This is a typical pivot arm awning.

http://www.supaview.com.au/wp-content/uploads/2013/06/Mesh-Drop-Arm-Awning.jpg

At the top there is a cylinder, onto which the fabric is rolled as the
awning is pulled up. The arm pivots on a bearing that is fixed to the
wall, with the other end being attached to a fixed position on the
awning. So, as the awning is extended, the lower end of the awning
describes a semicircle centred on the pivot bearing.

The motor fits inside one end of the cylinder. Here is a typical example:

https://www.somfy.co.uk/common/img/library//332x332/SUNEA_50_IO1.jpg

So the options I can think of are

a) Measure the angular position of the cylinder.

b) Paint a Gray code onto the fabric, and use an optical sensor to track
how much is extended.

c) Measure the angular position of the pivot arm.

d) Get the motor to report the angular position of the cylinder.

As I've said, some motors will do (d) for interior roller blinds, but
I've not found such a capability in exterior awning motors.

Option (b) has both cosmetic and longevity issues.

Option (a) might be feasible if enough of the cylinder remains exposed
at all times, and depending on how the top of the awning is enclosed.

Not sure about option (c).

Attach a simple sensor to a point at the bottom of the shade. Mount it
so it can swivel. Attach a bungee cord to the point you wish the shade
to end and connect that to the sensor so it always point along the line
of the bungee. Now the sensor will point along the line you wish the
shadow to fall, but not be blocked by short things like people.

Of course you may not like the bungee cord since it may block access
under the shade. But you don't like any other approach so far.

The only other approach I can imagine is to install an inertial angle
sensor on the support arm. This can be calibrated each time the awning
in retracted. It will let the position of the end of the awning be
calculated very accurately with a very small number of parameters set
during installation. The awning could then track the sun even when the
sun isn't visible. A separate sensor near the top of the awning could
sense total light allowing the awning to be retracted during low light
conditions.

--

Rick

Jim Thompson · Nov 7, 2015

On Thu, 29 Oct 2015 17:41:59 +1100, Sylvia Else
<sylvia@not.at.this.address> 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.

Computer Nerd Kev · Nov 8, 2015

In aus.electronics Sylvia Else <sylvia@not.at.this.address> wrote:

This is a typical pivot arm awning.

http://www.supaview.com.au/wp-content/uploads/2013/06/Mesh-Drop-Arm-Awning.jpg

At the top there is a cylinder, onto which the fabric is rolled as the
awning is pulled up. The arm pivots on a bearing that is fixed to the
wall, with the other end being attached to a fixed position on the
awning. So, as the awning is extended, the lower end of the awning
describes a semicircle centred on the pivot bearing.

The motor fits inside one end of the cylinder. Here is a typical example:

https://www.somfy.co.uk/common/img/library//332x332/SUNEA_50_IO1.jpg

So the options I can think of are

a) Measure the angular position of the cylinder.

b) Paint a Gray code onto the fabric, and use an optical sensor to track
how much is extended.

c) Measure the angular position of the pivot arm.

d) Get the motor to report the angular position of the cylinder.

As I've said, some motors will do (d) for interior roller blinds, but
I've not found such a capability in exterior awning motors.

Option (b) has both cosmetic and longevity issues.

Option (a) might be feasible if enough of the cylinder remains exposed
at all times, and depending on how the top of the awning is enclosed.

Not sure about option (c).

I would be inclined to go with option (c) using a potentiometer on the
support arm which then feeds to the ADC of the microcontroller. A
multiturn pot and a pulley or gearing might be required if the
resolution isn't good enough with a normal potentiometer. Or indeed
this could be used on the motor itself to measure its rotation, if
the movement of the pivot arm is effectively geared down too much.

The resolution of the ADC in the microcontroller must of course be
considered as well. Alternatively an optical rotary encoder such as
used in inkjet printers could be used, but would have to be well
shielded from ambient light.

--
__ __
#_ < |\| |< _#

Lasse Langwadt Christense · Nov 8, 2015

Den sřndag den 8. november 2015 kl. 19.23.37 UTC+1 skrev Ian Field:

"Computer Nerd Kev" <not@telling.you.invalid> wrote in message
news:n1m9hi$qt5$1@speranza.aioe.org...
In aus.electronics Sylvia Else <sylvia@not.at.this.address> wrote:

This is a typical pivot arm awning.

http://www.supaview.com.au/wp-content/uploads/2013/06/Mesh-Drop-Arm-Awning.jpg

At the top there is a cylinder, onto which the fabric is rolled as the
awning is pulled up. The arm pivots on a bearing that is fixed to the
wall, with the other end being attached to a fixed position on the
awning. So, as the awning is extended, the lower end of the awning
describes a semicircle centred on the pivot bearing.

The motor fits inside one end of the cylinder. Here is a typical example:

https://www.somfy.co.uk/common/img/library//332x332/SUNEA_50_IO1.jpg

So the options I can think of are

a) Measure the angular position of the cylinder.

b) Paint a Gray code onto the fabric, and use an optical sensor to track
how much is extended.

c) Measure the angular position of the pivot arm.

d) Get the motor to report the angular position of the cylinder.

As I've said, some motors will do (d) for interior roller blinds, but
I've not found such a capability in exterior awning motors.

Option (b) has both cosmetic and longevity issues.

Option (a) might be feasible if enough of the cylinder remains exposed
at all times, and depending on how the top of the awning is enclosed.

Not sure about option (c).

I would be inclined to go with option (c) using a potentiometer on the
support arm which then feeds to the ADC of the microcontroller.

If there's a microcontroller there anyway - a rotary encoder would be more
reliable than a pot, and they can usually rotate continuously as opposed to
the stops on a pot.

An opto-interruptor or Hall-effect sensor can tell the MCU where it is when
it needs to know.

stick on of the numerous cheap accelerometers on the arm and you have angle directly with no moving parts

-Lasse

Computer Nerd Kev · Nov 8, 2015

In aus.electronics Ian Field <gangprobing.alien@ntlworld.com> wrote:

"Computer Nerd Kev" <not@telling.you.invalid> wrote in message
news:n1m9hi$qt5$1@speranza.aioe.org...
In aus.electronics Sylvia Else <sylvia@not.at.this.address> wrote:

This is a typical pivot arm awning.

http://www.supaview.com.au/wp-content/uploads/2013/06/Mesh-Drop-Arm-Awning.jpg

At the top there is a cylinder, onto which the fabric is rolled as the
awning is pulled up. The arm pivots on a bearing that is fixed to the
wall, with the other end being attached to a fixed position on the
awning. So, as the awning is extended, the lower end of the awning
describes a semicircle centred on the pivot bearing.

The motor fits inside one end of the cylinder. Here is a typical example:

https://www.somfy.co.uk/common/img/library//332x332/SUNEA_50_IO1.jpg

So the options I can think of are

a) Measure the angular position of the cylinder.

b) Paint a Gray code onto the fabric, and use an optical sensor to track
how much is extended.

c) Measure the angular position of the pivot arm.

d) Get the motor to report the angular position of the cylinder.

As I've said, some motors will do (d) for interior roller blinds, but
I've not found such a capability in exterior awning motors.

Option (b) has both cosmetic and longevity issues.

Option (a) might be feasible if enough of the cylinder remains exposed
at all times, and depending on how the top of the awning is enclosed.

Not sure about option (c).

I would be inclined to go with option (c) using a potentiometer on the
support arm which then feeds to the ADC of the microcontroller.

If there's a microcontroller there anyway - a rotary encoder would be more
reliable than a pot, and they can usually rotate continuously as opposed to
the stops on a pot.

If you're connecting it to the pivot arm, then it will never have more than
180 deg. of movement unless you need to gear it up for higher resolution.

Agreed, a rotary encoder is likely to survive the elements better over
time if it is a suitable design.

--
__ __
#_ < |\| |< _#

Ian Field · Nov 9, 2015

"Computer Nerd Kev" <not@telling.you.invalid> wrote in message
news:n1m9hi$qt5$1@speranza.aioe.org...

In aus.electronics Sylvia Else <sylvia@not.at.this.address> wrote:

This is a typical pivot arm awning.

http://www.supaview.com.au/wp-content/uploads/2013/06/Mesh-Drop-Arm-Awning.jpg

At the top there is a cylinder, onto which the fabric is rolled as the
awning is pulled up. The arm pivots on a bearing that is fixed to the
wall, with the other end being attached to a fixed position on the
awning. So, as the awning is extended, the lower end of the awning
describes a semicircle centred on the pivot bearing.

The motor fits inside one end of the cylinder. Here is a typical example:

https://www.somfy.co.uk/common/img/library//332x332/SUNEA_50_IO1.jpg

So the options I can think of are

a) Measure the angular position of the cylinder.

b) Paint a Gray code onto the fabric, and use an optical sensor to track
how much is extended.

c) Measure the angular position of the pivot arm.

d) Get the motor to report the angular position of the cylinder.

As I've said, some motors will do (d) for interior roller blinds, but
I've not found such a capability in exterior awning motors.

Option (b) has both cosmetic and longevity issues.

Option (a) might be feasible if enough of the cylinder remains exposed
at all times, and depending on how the top of the awning is enclosed.

Not sure about option (c).

I would be inclined to go with option (c) using a potentiometer on the
support arm which then feeds to the ADC of the microcontroller.

If there's a microcontroller there anyway - a rotary encoder would be more
reliable than a pot, and they can usually rotate continuously as opposed to
the stops on a pot.

An opto-interruptor or Hall-effect sensor can tell the MCU where it is when
it needs to know.

krw · Nov 9, 2015

On Sun, 8 Nov 2015 10:32:41 -0800 (PST), Lasse Langwadt Christensen
<langwadt@fonz.dk> wrote:

Den sřndag den 8. november 2015 kl. 19.23.37 UTC+1 skrev Ian Field:
"Computer Nerd Kev" <not@telling.you.invalid> wrote in message
news:n1m9hi$qt5$1@speranza.aioe.org...
In aus.electronics Sylvia Else <sylvia@not.at.this.address> wrote:

This is a typical pivot arm awning.

http://www.supaview.com.au/wp-content/uploads/2013/06/Mesh-Drop-Arm-Awning.jpg

At the top there is a cylinder, onto which the fabric is rolled as the
awning is pulled up. The arm pivots on a bearing that is fixed to the
wall, with the other end being attached to a fixed position on the
awning. So, as the awning is extended, the lower end of the awning
describes a semicircle centred on the pivot bearing.

The motor fits inside one end of the cylinder. Here is a typical example:

https://www.somfy.co.uk/common/img/library//332x332/SUNEA_50_IO1.jpg

So the options I can think of are

a) Measure the angular position of the cylinder.

b) Paint a Gray code onto the fabric, and use an optical sensor to track
how much is extended.

c) Measure the angular position of the pivot arm.

d) Get the motor to report the angular position of the cylinder.

As I've said, some motors will do (d) for interior roller blinds, but
I've not found such a capability in exterior awning motors.

Option (b) has both cosmetic and longevity issues.

Option (a) might be feasible if enough of the cylinder remains exposed
at all times, and depending on how the top of the awning is enclosed.

Not sure about option (c).

I would be inclined to go with option (c) using a potentiometer on the
support arm which then feeds to the ADC of the microcontroller.

If there's a microcontroller there anyway - a rotary encoder would be more
reliable than a pot, and they can usually rotate continuously as opposed to
the stops on a pot.

An opto-interruptor or Hall-effect sensor can tell the MCU where it is when
it needs to know.

stick on of the numerous cheap accelerometers on the arm and you have angle directly with no moving parts

Except the connecting wires.

Sylvia Else · Nov 9, 2015

On 7/11/2015 11:47 AM, Jim Thompson wrote:

On Thu, 29 Oct 2015 17:41:59 +1100, Sylvia Else
sylvia@not.at.this.address> 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.

Maybe something like this...

http://www.analog-innovations.com/SED/AwningController.pdf

...Jim Thompson

Well, that's pretty much what I had in mind, though given the
orientation of the window (westward), it only needs one sensor below it
- there's no situation in which partial retraction makes any sense.

As it happens, it's occurred to me that since the awnings are custom
made to fit the window, I can presumably specify that the cylinder be a
few centimetres longer than required for the fabric, and use the extra
space to create an angular position sensor. This has the advantage of
avoiding any sensors below the window, which were going to be a
challenge to connect in an aesthetically acceptable way on a brick wall
facing the garden (yard, to those in the USA).

I still need a sensor somewhere above the window line to tell me whether
there's any sunlight justifying awning extension, to avoid extending on
cloudy days

Sourcing components without excessive shipping costs can be a problem
here in Australia, and sometimes it makes sense to buy a moderately
expensive component. I'm considering using one of these behind glass.

http://au.rs-online.com/web/p/photodiodes/6278366/

None of this can happen until I move house, which isn't for a couple of
months, so there's time to reflect on the best design.

Sylvia.

Jim Thompson · Nov 9, 2015

On Mon, 9 Nov 2015 11:56:21 +1100, Sylvia Else
<sylvia@not.at.this.address> wrote:

On 7/11/2015 11:47 AM, Jim Thompson wrote:
On Thu, 29 Oct 2015 17:41:59 +1100, Sylvia Else
sylvia@not.at.this.address> 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.

Maybe something like this...

http://www.analog-innovations.com/SED/AwningController.pdf

...Jim Thompson

Well, that's pretty much what I had in mind, though given the
orientation of the window (westward), it only needs one sensor below it
- there's no situation in which partial retraction makes any sense.

As it happens, it's occurred to me that since the awnings are custom
made to fit the window, I can presumably specify that the cylinder be a
few centimetres longer than required for the fabric, and use the extra
space to create an angular position sensor. This has the advantage of
avoiding any sensors below the window, which were going to be a
challenge to connect in an aesthetically acceptable way on a brick wall
facing the garden (yard, to those in the USA).

I still need a sensor somewhere above the window line to tell me whether
there's any sunlight justifying awning extension, to avoid extending on
cloudy days

Sourcing components without excessive shipping costs can be a problem
here in Australia, and sometimes it makes sense to buy a moderately
expensive component. I'm considering using one of these behind glass.

http://au.rs-online.com/web/p/photodiodes/6278366/

None of this can happen until I move house, which isn't for a couple of
months, so there's time to reflect on the best design.

Sylvia.

krw · Nov 9, 2015

On Mon, 9 Nov 2015 13:14:18 +1100, Sylvia Else
<sylvia@not.at.this.address> wrote:

On 9/11/2015 12:13 PM, Jim Thompson wrote:
On Mon, 9 Nov 2015 11:56:21 +1100, Sylvia Else
sylvia@not.at.this.address> wrote:

On 7/11/2015 11:47 AM, Jim Thompson wrote:
On Thu, 29 Oct 2015 17:41:59 +1100, Sylvia Else
sylvia@not.at.this.address> 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.

Maybe something like this...

http://www.analog-innovations.com/SED/AwningController.pdf

...Jim Thompson

Well, that's pretty much what I had in mind, though given the
orientation of the window (westward), it only needs one sensor below it
- there's no situation in which partial retraction makes any sense.

As it happens, it's occurred to me that since the awnings are custom
made to fit the window, I can presumably specify that the cylinder be a
few centimetres longer than required for the fabric, and use the extra
space to create an angular position sensor. This has the advantage of
avoiding any sensors below the window, which were going to be a
challenge to connect in an aesthetically acceptable way on a brick wall
facing the garden (yard, to those in the USA).

I still need a sensor somewhere above the window line to tell me whether
there's any sunlight justifying awning extension, to avoid extending on
cloudy days

Sourcing components without excessive shipping costs can be a problem
here in Australia, and sometimes it makes sense to buy a moderately
expensive component. I'm considering using one of these behind glass.

http://au.rs-online.com/web/p/photodiodes/6278366/

None of this can happen until I move house, which isn't for a couple of
months, so there's time to reflect on the best design.

Sylvia.

Once lower sensor is shaded, how do you know when to raise the awning?

Since the window is west facing, the awning has to descend throughout
the afternoon, and is only retracted once the sun sets. At that point
the sensor above the window ceases to be in sunlight, which triggers the
complete retraction of the awning.

For a north facing window (given that I'm in the southern hemisphere)
things would be more complicated and a sensor based system would indeed
need two below the window.

It just needs to be a little below the window. In the morning, just
keep the awning (just) in the light. When it gets shaded, move it up
a little. Use a timer to measure how fast you're moving it. When you
think it should be moved and it doesn't have to be, start keeping the
window (just) in the dark (repeat the above, backwards). The "little
below the window" hides the hysterisis.

Sylvia Else · Nov 9, 2015

On 9/11/2015 12:13 PM, Jim Thompson wrote:

On Mon, 9 Nov 2015 11:56:21 +1100, Sylvia Else
sylvia@not.at.this.address> wrote:

On 7/11/2015 11:47 AM, Jim Thompson wrote:
On Thu, 29 Oct 2015 17:41:59 +1100, Sylvia Else
sylvia@not.at.this.address> 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.

Maybe something like this...

http://www.analog-innovations.com/SED/AwningController.pdf

...Jim Thompson

Well, that's pretty much what I had in mind, though given the
orientation of the window (westward), it only needs one sensor below it
- there's no situation in which partial retraction makes any sense.

As it happens, it's occurred to me that since the awnings are custom
made to fit the window, I can presumably specify that the cylinder be a
few centimetres longer than required for the fabric, and use the extra
space to create an angular position sensor. This has the advantage of
avoiding any sensors below the window, which were going to be a
challenge to connect in an aesthetically acceptable way on a brick wall
facing the garden (yard, to those in the USA).

I still need a sensor somewhere above the window line to tell me whether
there's any sunlight justifying awning extension, to avoid extending on
cloudy days

Sourcing components without excessive shipping costs can be a problem
here in Australia, and sometimes it makes sense to buy a moderately
expensive component. I'm considering using one of these behind glass.

http://au.rs-online.com/web/p/photodiodes/6278366/

None of this can happen until I move house, which isn't for a couple of
months, so there's time to reflect on the best design.

Sylvia.

Once lower sensor is shaded, how do you know when to raise the awning?

Since the window is west facing, the awning has to descend throughout
the afternoon, and is only retracted once the sun sets. At that point
the sensor above the window ceases to be in sunlight, which triggers the
complete retraction of the awning.

For a north facing window (given that I'm in the southern hemisphere)
things would be more complicated and a sensor based system would indeed
need two below the window.

Sylvia.

krw · Nov 9, 2015

On Sun, 08 Nov 2015 18:13:52 -0700, Jim Thompson
<To-Email-Use-The-Envelope-Icon@On-My-Web-Site.com> wrote:

On Mon, 9 Nov 2015 11:56:21 +1100, Sylvia Else
sylvia@not.at.this.address> wrote:

On 7/11/2015 11:47 AM, Jim Thompson wrote:
On Thu, 29 Oct 2015 17:41:59 +1100, Sylvia Else
sylvia@not.at.this.address> 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.

Maybe something like this...

http://www.analog-innovations.com/SED/AwningController.pdf

...Jim Thompson

Well, that's pretty much what I had in mind, though given the
orientation of the window (westward), it only needs one sensor below it
- there's no situation in which partial retraction makes any sense.

As it happens, it's occurred to me that since the awnings are custom
made to fit the window, I can presumably specify that the cylinder be a
few centimetres longer than required for the fabric, and use the extra
space to create an angular position sensor. This has the advantage of
avoiding any sensors below the window, which were going to be a
challenge to connect in an aesthetically acceptable way on a brick wall
facing the garden (yard, to those in the USA).

I still need a sensor somewhere above the window line to tell me whether
there's any sunlight justifying awning extension, to avoid extending on
cloudy days

Sourcing components without excessive shipping costs can be a problem
here in Australia, and sometimes it makes sense to buy a moderately
expensive component. I'm considering using one of these behind glass.

http://au.rs-online.com/web/p/photodiodes/6278366/

None of this can happen until I move house, which isn't for a couple of
months, so there's time to reflect on the best design.

Sylvia.
]
Once lower sensor is shaded, how do you know when to raise the awning?

You need to define three states, raise, stop, lower.

Or hunt. It doesn't have to happen very fast and you know the
direction everywhere but the endpoints.

Driver to drive?

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