A different kind of motion sensing security light?

[John Doe]

Correct me if I'm wrong on any of this, but... The motion sensor
(part) output constantly varies. Only when its output reaches a
certain level relative to its normal state, then it trips a switch
that drives the light for some period of time. Then the lightbulb
switches off and waits for another significant change in
detection.

What I would like to do is have a lightbulb or LED
brightness/intensity follow the motion sensor output part. In
other words... If a bird flies by, the lightbulb would momentarily
dimly light. If a person walks into close range, the lightbulb
would continuously shine brightly. If the person walked behind
some object, the lightbulb would go off, and then when they
reappeared, the lightbulb would come back on. Hopefully I'm not
over describing this, but I'll be happy to provide more
description if asked.

Does such a device (or close) already exist for purchase in a
store?

The sensor output part typically could not be connected to an LED
without putting an amplifier on it? Anybody do this before, any
schematic?

Thanks.





--
Crossposted, feel free to delete the other group(s).
BTW. I'm not suggesting that anybody else could use or enjoy this.

[Jamie]

John Doe wrote:
> Correct me if I'm wrong on any of this, but... The motion sensor
> (part) output constantly varies. Only when its output reaches a
> certain level relative to its normal state, then it trips a switch
> that drives the light for some period of time. Then the lightbulb
> switches off and waits for another significant change in
> detection.
>
> What I would like to do is have a lightbulb or LED
> brightness/intensity follow the motion sensor output part. In
> other words... If a bird flies by, the lightbulb would momentarily
> dimly light. If a person walks into close range, the lightbulb
> would continuously shine brightly. If the person walked behind
> some object, the lightbulb would go off, and then when they
> reappeared, the lightbulb would come back on. Hopefully I'm not
> over describing this, but I'll be happy to provide more
> description if asked.
>
> Does such a device (or close) already exist for purchase in a
> store?
>
> The sensor output part typically could not be connected to an LED
> without putting an amplifier on it? Anybody do this before, any
> schematic?
>
> Thanks.
>

look at ultrasonic distance sensors. You can get outputs that
are analog for a distance reading of an object infront of it or
a switched output when an object is with in range.

http://store.mp3car.com/ProductDetails.asp?ProductCode=COM-078&cvsfa=3961&cvsfe=2&cvsfhu=434f4d2d303738&gclid=CJ2d-vabmbUCFUid4AodwxIAIg


Jamie

[Tim Williams]

AFAIK, pyroelectric sensors are a "single pixel" sort of thing, so they
don't know if the scene is moving, only if the average IR changes. Which it
does when someone comes into view or jumps out of the shadows, but it
doesn't do jack if someone walks around freely while holding up a
room-temperature blanket, or moves in the scene while presenting an equal
viewing cross section (probably tricky to do).

The output is positive or negative charge, corresponding to the change in
temperature viewed. Into a high resistive load (say, like something Phil
might be working on right now :) ), this has a time constant (the sensor's
just an insulating crystal), so it automatically centers after a while. In
other words, it's a temperature differentiator (for pedants, that's the RC
kind). Obviously, a motion detector needs only a window comparator; you
could use a suitably calibrated gain instead (followed by a full-wave active
rectifier), and maybe a lowpass, or falling slew rate limiter, to enhance
the effect.

Still might not be quite as intended; if the detector response is equal
across the viewing angle, then a person walking across the path will cause
it to light up (or down), then not do so much (depending on how the sensor
sees a walking body), then light up again on leaving the frame.

Tim

--
Deep Friar: a very philosophical monk.
Website: http://www.seventransistorlabs.com/

"John Doe" <jd...@usenetlove.invalid> wrote in message
news:keklhq$s3c$1...@dont-email.me...

[John Doe]

"Tim Williams" <tmoranwms charter.net> wrote:

> AFAIK, pyroelectric sensors are a "single pixel" sort of thing,
> so they don't know if the scene is moving, only if the average
> IR changes.

That's all I want. It's not going to be the only part of the
system, and I can interpret the output. I guess it could even be a
very short (1 second or less) on time by a common passive infrared
motion detector, so that it would flash during its detection time.

[Phil Hobbs]

I don't know about this particular sensor, but most of the commercial
PIR elements for porch lights have the FET built in. Maybe the 47k is
the source resistor of the JFET follower?

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510 USA
+1 845 480 2058

hobbs at electrooptical dot net
http://electrooptical.net

[harry]

You can buy sensors that have a restricted/adjustable "target" size.
To eliminate nuisance operations from small animals.

There will always be an amplifier and relay in the circuit.

[tra...@optonline.net]

On Feb 3, 1:55 am, Phil Hobbs <pcdhSpamMeSensel...@electrooptical.net>
wrote:

> On 2/3/2013 1:41 AM, John Doe wrote:
>
> > "Tim Williams" <tmoranwms charter.net> wrote:
>
> >> AFAIK, pyroelectric sensors are a "single pixel" sort of thing,
> >> so they don't know if the scene is moving, only if the average
> >> IR changes.
>
> > That's all I want. It's not going to be the only part of the
> > system, and I can interpret the output. I guess it could even be a
> > very short (1 second or less) on time by a common passive infrared
> > motion detector, so that it would flash during its detection time.
>
> I don't know about this particular sensor, but most of the commercial
> PIR elements for porch lights have the FET built in.  Maybe the 47k is
> the source resistor of the JFET follower?
>
> Cheers
>
> Phil Hobbs
>

I doubt he's going to find a finished product that does what
he wants. The products ready to be mounted have not
only the sensor, but as he points, out the circuitry that
turns it into some kind of on/off output that is needed for
the product.

However those motion detector products use ICs which
he can probably find. Some of the ICs provide an analog
output that he could use together with his own circuit.
Here are examples from one company:

http://www.mouser.com/ds/2/281/s21e-6137.pdf

[tra...@optonline.net]

> There will always be an amplifier and relay in the circuit.- Hide quoted text -
>
> - Show quoted text -

Wrong yet again. harry is like a cosmic black hole of ignorance, no
real knowledge can exist anywhere near him.

[Phil Hobbs]

On Page 3 of that brochure there's a schematic like the one I'm talking
about--the sensor load resistor is inside the capsule, and the external
resistor is the source load for the JFET follower. That's the usual
approach IME.

Porch light sensors are actually pretty cool devices--they use a split
pyroelectric sensor, with the two halves wired opposing each other. A
segmented Fresnel lens casts a dozen or so images of the scene, so as
you walk up to the door, a dozen of you cross the sensor, causing about
a 10- or 12- cycle AC waveform, which is detected with a comparator.

The split cell makes the sensor much more resistant to changes in
ambient temperature, power supply voltage, and that sort of stuff. A
cute design--whoever came up with it should be better known.

[Jamie]

Tim Williams wrote:

> AFAIK, pyroelectric sensors are a "single pixel" sort of thing, so they
> don't know if the scene is moving, only if the average IR changes.
> Which it does when someone comes into view or jumps out of the shadows,
> but it doesn't do jack if someone walks around freely while holding up a
> room-temperature blanket, or moves in the scene while presenting an
> equal viewing cross section (probably tricky to do).
>
> The output is positive or negative charge, corresponding to the change
> in temperature viewed. Into a high resistive load (say, like something
> Phil might be working on right now :) ), this has a time constant (the
> sensor's just an insulating crystal), so it automatically centers after
> a while. In other words, it's a temperature differentiator (for
> pedants, that's the RC kind). Obviously, a motion detector needs only a
> window comparator; you could use a suitably calibrated gain instead
> (followed by a full-wave active rectifier), and maybe a lowpass, or
> falling slew rate limiter, to enhance the effect.
>
> Still might not be quite as intended; if the detector response is equal
> across the viewing angle, then a person walking across the path will
> cause it to light up (or down), then not do so much (depending on how
> the sensor sees a walking body), then light up again on leaving the frame.
>
> Tim
>

we used a few of those for wire break and jerk detectors just as the
conductor comes out of the induction heater and prior to entering the
extrusion head assembly.

Since the conductor will jerk with a over sized section going through
or a breakage, it works out well. There is also a small air jet that
sits infront of the IR passive glass to keep the dust off.

Jamie

[SoothSayer]

On Sun, 03 Feb 2013 01:55:03 -0500, Phil Hobbs
<pcdhSpamM...@electrooptical.net> wrote:

>On 2/3/2013 1:41 AM, John Doe wrote:
>> "Tim Williams" <tmoranwms charter.net> wrote:
>>
>>> AFAIK, pyroelectric sensors are a "single pixel" sort of thing,
>>> so they don't know if the scene is moving, only if the average
>>> IR changes.
>>
>> That's all I want. It's not going to be the only part of the
>> system, and I can interpret the output. I guess it could even be a
>> very short (1 second or less) on time by a common passive infrared
>> motion detector, so that it would flash during its detection time.
>>
>
>I don't know about this particular sensor, but most of the commercial
>PIR elements for porch lights have the FET built in. Maybe the 47k is
>the source resistor of the JFET follower?
>
>Cheers
>
>Phil Hobbs

One must also be *VERY* careful when handling/installing the device as
well. They usually come with shorting wires on the leads they are so
worried.

Some FETs can be blown by an ESD field, particularly prior to being
installed. Does not even require contact.

That is why a smock is required at the 'proper' ESD safe workstation.
It 'contains' whatever fields you and your insulative clothing may be
carrying.

[John Fields]

On Sun, 3 Feb 2013 03:28:58 +0000 (UTC), John Doe
<jd...@usenetlove.invalid> wrote:

>Correct me if I'm wrong on any of this, but... The motion sensor
>(part) output constantly varies.

---
Generally, no.

The common pyroelectric motion sensor outputs a single pulse when the
incident radiation which falls on the detector has a higher or lower
wavelength than that of the ambient radiation within the field of view
of the transducer.
---

>Only when its output reaches a
>certain level relative to its normal state, then it trips a switch
>that drives the light for some period of time. Then the lightbulb
>switches off and waits for another significant change in
>detection.

---
All true, but since it's only the rate of change of amplitude of the
pulse - which goes with the velocity of the target - which drives the
switch, there's no range information to be gleaned.

There are sensor arrays available with multiple transducers.

Knowing, then, the focal length of the lens, the distance between the
transducers and the difference in time between the responses of the
transducers, the range to the target can be calculated.
---

>What I would like to do is have a lightbulb or LED
>brightness/intensity follow the motion sensor output part. In
>other words... If a bird flies by, the lightbulb would momentarily
>dimly light. If a person walks into close range, the lightbulb
>would continuously shine brightly. If the person walked behind
>some object, the lightbulb would go off, and then when they
>reappeared, the lightbulb would come back on. Hopefully I'm not
>over describing this, but I'll be happy to provide more
>description if asked.
>
>Does such a device (or close) already exist for purchase in a
>store?

---
Someone already mentioned a TOF SONAR sensor, which would be ideal if
it could resolve distance to the accuracy you require, which will vary
depending on temperature, humidity, and atmospheric pressure.

Can you address that?
---

>The sensor output part typically could not be connected to an LED
>without putting an amplifier on it? Anybody do this before, any
>schematic?
>
>Thanks.
--

JF

[John Doe]

John Fields <jfields austininstruments.com> wrote:

> John Doe <jdoe usenetlove.invalid> wrote:
>
>>Correct me if I'm wrong on any of this, but... The motion sensor
>>(part) output constantly varies.

> Generally, no.
>
> The common pyroelectric motion sensor outputs a single pulse
> when the incident radiation which falls on the detector has a
> higher or lower wavelength than that of the ambient radiation
> within the field of view of the transducer.

I guess that means there is no analog output. So it's not like a
photo resistor. I've played with photo resistors, controlling a
variable frequency connected to a speaker. Aiming it towards a TV
produced amusing and rapidly changing frequencies. I wonder if
there are hypersensitive photo resistors that might do (with a
wide field of view), maybe infrared or whatever. Or maybe that has
already been suggested under different terminology.

> Someone already mentioned a TOF SONAR sensor, which would be
> ideal if it could resolve distance to the accuracy you require,
> which will vary depending on temperature, humidity, and
> atmospheric pressure.
>
> Can you address that?

I don't need to know distance or speed. All I want to sense is
changes in radiation in the area. But if the changes in intensity
are great, that might suggest the object is either large or
nearby. I guess that would be a function of something like a
long-range omnidirectional (or wide angle, as long as it's view is
not narrow) infrared photo resistor/sensor if there is such a
thing. I'll look.

Distance to sense a person, to noticeably and distinctly change
the output, needs to be at least 20 feet, preferably 50-100.




--
Thanks to the replies.

[mike]

https://www.google.com/search?num=100&hl=en&lr=&safe=images&tbo=d&as_qdr=all&q=xbox+motion+detection&oq=xbox+motion+detection&gs_l=serp.12..0j0i5i30l2j0i8i10i30j0i8i30l3.7907.7907.0.10998.1.1.0.0.0.0.934.934.6-1.1.0.les%3B..0.0...1c..2.serp.z6TfNc9RhwA

[John Doe]

To be clear...
actually, what I played with might be called a photodiode (not a
photoresistor), it looked like an ordinary white LED, it didn't have
the squiggly wires inside

[John Doe]

John Fields <jfields austininstruments.com> wrote:

> The common pyroelectric motion sensor outputs a single pulse
> when the incident radiation which falls on the detector has a
> higher or lower wavelength than that of the ambient radiation
> within the field of view of the transducer.

FWIW...
I will plan to use that, that will be easiest. I will see if the
output can be made to flash a light as long as motion is being
detected, without a long delay or long on-time.

[Jasen Betts]

On 2013-02-03, John Doe <jd...@usenetlove.invalid> wrote:
> What I would like to do is have a lightbulb or LED
> brightness/intensity follow the motion sensor output part. In
> other words... If a bird flies by, the lightbulb would momentarily
> dimly light. If a person walks into close range, the lightbulb
> would continuously shine brightly. If the person walked behind
> some object, the lightbulb would go off, and then when they
> reappeared, the lightbulb would come back on. Hopefully I'm not
> over describing this, but I'll be happy to provide more
> description if asked.

these sensors detect movement by having two "pixels" that are focused by
the lens onto alternating bands of the scene, the sensors only produce
a signal proportional to the rate of change of average temperature of
the area viewed by the pixel.

a person walking across the fiels od view would produce a signal that
alternates between the two sensors.

> Does such a device (or close) already exist for purchase in a
> store?

I've not heard of one.

> The sensor output part typically could not be connected to an LED
> without putting an amplifier on it? Anybody do this before, any
> schematic?
>
> Thanks.
>
>
>
>
>


--

⚂⚃ 100% natural

--- news://freenews.netfront.net/ - complaints: ne...@netfront.net ---

[Mark Zenier]

In article <keku69$6s1$1...@dont-email.me>,

Tim Williams <tmor...@charter.net> wrote:
>AFAIK, pyroelectric sensors are a "single pixel" sort of thing, so they
>don't know if the scene is moving, only if the average IR changes. Which it
>does when someone comes into view or jumps out of the shadows, but it
>doesn't do jack if someone walks around freely while holding up a
>room-temperature blanket, or moves in the scene while presenting an equal
>viewing cross section (probably tricky to do).

They're two "pixels" in an AC coupled differential circuit.
The optics are set so that the sensors see adjacent areas and
react to fast changes. (You can fool them if you move real slow).

The best analogy of the optics is to spread your fingers apart and put the
flat of your palms together so that the fingers interleave. One sensor
per "hand", with the views of the two sensors interlinked. Any movement
quick enough, and one sensor will decrease while the other increases.
The response is usually flat in one plane, determined by the way the
plastic lens is molded.

Radio-Electronics/Electronic Now magazine had a long distance pyroelectric
sensor project that used a motor driven mechanical chopper, back when
these things were new.

Mark Zenier mze...@eskimo.com
Googleproofaddress(account:mzenier provider:eskimo domain:com)

[Robert Macy]

On Feb 3, 8:17 am, mzen...@eskimo.com (Mark Zenier) wrote:
> In article <keku69$6s...@dont-email.me>,

>
> Tim Williams <tmoran...@charter.net> wrote:
> >AFAIK, pyroelectric sensors are a "single pixel" sort of thing, so they
> >don't know if the scene is moving, only if the average IR changes.  Which it
> >does when someone comes into view or jumps out of the shadows, but it
> >doesn't do jack if someone walks around freely while holding up a
> >room-temperature blanket, or moves in the scene while presenting an equal
> >viewing cross section (probably tricky to do).
>
> They're two "pixels" in an AC coupled  differential circuit.
> The optics are set so that the sensors see adjacent areas and
> react to fast changes.  (You can fool them if you move real slow).
>
> The best analogy of the optics is to spread your fingers apart and put the
> flat of your palms together so that the fingers interleave.  One sensor
> per "hand", with the views of the two sensors interlinked.  Any movement
> quick enough, and one sensor will decrease while the other increases.
> The response is usually flat in one plane, determined by the way the
> plastic lens is molded.
>
> Radio-Electronics/Electronic Now magazine had a long distance pyroelectric
> sensor project that used a motor driven mechanical chopper, back when
> these things were new.
>

> Mark Zenier  mzen...@eskimo.com

> Googleproofaddress(account:mzenier provider:eskimo domain:com)

If you're going mechanical, why not make it a capacitive sensor.
Chopping the field from the intruder. Since you kknow the speed of the
chopping, you can synchronously detect and obtain EXACTLY the type of
signal you want. ...I think.

[John Fields]

On Sun, 03 Feb 2013 18:55:42 -0600, John Fields
<jfi...@austininstruments.com> wrote:


>All true, but since it's only the rate of change of amplitude of the
>pulse - which goes with the velocity of the target - which drives the
>switch, there's no range information to be gleaned.
>
>There are sensor arrays available with multiple transducers.
>
>Knowing, then, the focal length of the lens, the distance between the
>transducers and the difference in time between the responses of the
>transducers, the range to the target can be calculated.

---

Oops...

That's wrong.

A target with a high velocity far from the sensor could the elicit the
same response from the sensor as a nearer, slower target, so range
can't be resolved that way.

Sorry 'bout that.

--
JF

[John Fields]

---
Then it's more than likely either a photodiode or a phototransistor.

Can you post a schematic of the circuit you played with?

--
JF

[John Fields]

---
I've done long-range PIR detection before and 20 feet is pretty easy,
but 100 feet is going to take some care.

Can you tell us a little more about your application?

--
JF

[John Doe]

John Fields <jfields austininstruments.com> wrote:

> John Doe <jdoe usenetlove.invalid> wrote:
>
>>To be clear... actually, what I played with might be called a
>>photodiode (not a photoresistor), it looked like an ordinary

>>white [clear] LED, it didn't have the squiggly wires inside

> Then it's more than likely either a photodiode or a
> phototransistor.
>
> Can you post a schematic of the circuit you played with?

Google produces 280 results for my "Tonal Voltmeter". I'm sure it
was just that, using a photodiode to vary resistance/voltage. It
looked like a clear T1 LED. I have nothing left (except fond
memories) from experimenting with electronics.

[John Fields]

---
eternalseptember.org, huh?

Bye.

--
JF

[John Doe]

John Fields <jfields austininstruments.com> wrote:

> John Doe <jdoe usenetlove.invalid> wrote:
>>John Fields <jfields austininstruments.com> wrote:
>>> John Doe <jdoe usenetlove.invalid> wrote:
>>>
>>>>To be clear... actually, what I played with might be called a
>>>>photodiode (not a photoresistor), it looked like an ordinary
>>>>white [clear] LED, it didn't have the squiggly wires inside
>>
>>> Then it's more than likely either a photodiode or a
>>> phototransistor.
>>>
>>> Can you post a schematic of the circuit you played with?
>>
>>Google produces 280 results for my "Tonal Voltmeter". I'm sure
>>it was just that, using a photodiode to vary resistance/voltage.
>>It looked like a clear T1 LED. I have nothing left (except fond
>>memories) from experimenting with electronics.
>
> --- eternalseptember.org, huh?

Yes?

As I said in two prior separate replies... I am FWIW satisfied
with the discussion. I will probably use a cheap motion detector,
and maybe try to shorten the on-time so that the light blinks
while motion is being sensed.

--












>
> Bye.
>
> --
> JF
>
>

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> Subject: Re: A different kind of motion sensing security light?
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[Ian Field]

"Tim Williams" <tmor...@charter.net> wrote in message
news:keku69$6s1$1...@dont-email.me...

> AFAIK, pyroelectric sensors are a "single pixel" sort of thing, so they
> don't know if the scene is moving, only if the average IR changes. Which
> it does when someone comes into view or jumps out of the shadows,

If you mean PIR motion detectors, they usually have twin element pyrometers
(thin film thermistor) a motion of a IR source (person) is "grated" to
produce a gross change from one element to the other - this is done in
various ways such as Freznel type lenses (special IR transparent material)
and faceted surface reflecting reflectors.

[Ian Field]

<tra...@optonline.net> wrote in message
news:68dc88eb-af9d-4cc2...@r3g2000yqd.googlegroups.com...

> On Feb 3, 1:55 am, Phil Hobbs <pcdhSpamMeSensel...@electrooptical.net>
> wrote:
>> On 2/3/2013 1:41 AM, John Doe wrote:
>>
>> > "Tim Williams" <tmoranwms charter.net> wrote:
>>
>> >> AFAIK, pyroelectric sensors are a "single pixel" sort of thing,
>> >> so they don't know if the scene is moving, only if the average
>> >> IR changes.
>>
>> > That's all I want. It's not going to be the only part of the
>> > system, and I can interpret the output. I guess it could even be a
>> > very short (1 second or less) on time by a common passive infrared
>> > motion detector, so that it would flash during its detection time.
>>
>> I don't know about this particular sensor, but most of the commercial
>> PIR elements for porch lights have the FET built in. Maybe the 47k is
>> the source resistor of the JFET follower?
>>
>> Cheers
>>
>> Phil Hobbs
>>
>
>
> I doubt he's going to find a finished product that does what
> he wants. The products ready to be mounted have not
> only the sensor, but as he points, out the circuitry that
> turns it into some kind of on/off output that is needed for
> the product.
>
> However those motion detector products use ICs which
> he can probably find.

Most of the examples I pulled apart and hand traced the circuit years ago,
were based on the LM324.

[Jamie]

That's strange that you would call them thermistors? TO me a thermistor
is a slow reacting device? But yet we have an application where we use a
basic pyroelectric 3 wire detector for detecting vibration of small
conductor as it exits from an induction heater. This vibration can get
up to around 1khz or more when the wire snaps for what ever reason.

I would think a thermistor device would be a little slow for this
wouldn't you?

Maybe the units I used have different smoke in side.

Jamie

[Jasen Betts]

On 2013-02-06, Jamie <jamie_ka1lpa_not_v...@charter.net> wrote:
> Ian Field wrote:
>
>>
>>
>> "Tim Williams" <tmor...@charter.net> wrote in message
>> news:keku69$6s1$1...@dont-email.me...
>>
>>> AFAIK, pyroelectric sensors are a "single pixel" sort of thing, so
>>> they don't know if the scene is moving, only if the average IR
>>> changes. Which it does when someone comes into view or jumps out of
>>> the shadows,
>>
>>
>> If you mean PIR motion detectors, they usually have twin element
>> pyrometers (thin film thermistor) a motion of a IR source (person) is
>> "grated" to produce a gross change from one element to the other - this
>> is done in various ways such as Freznel type lenses (special IR
>> transparent material) and faceted surface reflecting reflectors.
>
> That's strange that you would call them thermistors?

AIUI they are closer to capacitor than resistor, the device does sense
its own temperature though, they detect remote temperature by
black-body radiation changing the temperature of the sensor.

TO me a thermistor
> is a slow reacting device? But yet we have an application where we use a
> basic pyroelectric 3 wire detector for detecting vibration of small
> conductor as it exits from an induction heater. This vibration can get
> up to around 1khz or more when the wire snaps for what ever reason.
>
> I would think a thermistor device would be a little slow for this
> wouldn't you?

if you could make it thin enough it would work.

[Ian Field]

"Jamie" <jamie_ka1lpa_not_v...@charter.net> wrote in message
news:j_gQs.69570$H5.2...@newsfe28.iad...

> Ian Field wrote:
>
>>
>>
>> "Tim Williams" <tmor...@charter.net> wrote in message
>> news:keku69$6s1$1...@dont-email.me...
>>
>>> AFAIK, pyroelectric sensors are a "single pixel" sort of thing, so they
>>> don't know if the scene is moving, only if the average IR changes.
>>> Which it does when someone comes into view or jumps out of the shadows,
>>
>>
>> If you mean PIR motion detectors, they usually have twin element
>> pyrometers (thin film thermistor) a motion of a IR source (person) is
>> "grated" to produce a gross change from one element to the other - this
>> is done in various ways such as Freznel type lenses (special IR
>> transparent material) and faceted surface reflecting reflectors.
>
> That's strange that you would call them thermistors? TO me a thermistor
> is a slow reacting device?

I have some continuity/voltage checkers with a thin film PTC in series with
an inverse parallel pair of high efficiency LEDs (2mA rating) - the series
PTC thermistor can react fast enough to protect the LEDs from application to
voltages upto 450V.

[John Fields]

On Tue, 5 Feb 2013 21:53:57 -0000, "Ian Field"
<gangprob...@ntlworld.com> wrote:

>
>
>"Tim Williams" <tmor...@charter.net> wrote in message
>news:keku69$6s1$1...@dont-email.me...
>> AFAIK, pyroelectric sensors are a "single pixel" sort of thing, so they
>> don't know if the scene is moving, only if the average IR changes. Which
>> it does when someone comes into view or jumps out of the shadows,
>
>If you mean PIR motion detectors, they usually have twin element pyrometers
>(thin film thermistor)

---
The sensor elements aren't thermistors, which are made from sintered
metal oxides (NTC) or a doped polycrystalline ceramic (PTC).

They're made from gallium nitride, cesium nitrate, polyvinyl
fluorides, derivatives of phenylpyridine, or cobalt phthalocyanine.

Moreover, thermistors exhibit a static change in resistance with a
change in temperature, while PIR elements generate a charge when
abruptly heated or cooled below their ambient temperature.
---

>a motion of a IR source (person) is "grated" to
>produce a gross change from one element to the other - this is done in
>various ways such as Freznel type lenses (special IR transparent material)

---
"Fresnel" lens, and they're available in many more materials than just
IR transmitting.

--
JF

[John Fields]

---
Apples and oranges.

--
JF

[Ian Field]

"John Fields" <jfi...@austininstruments.com> wrote in message
news:2f55h8hgb34k7dk6b...@4ax.com...

Your usual disingenuous self!

My point is that a thin film thermistor can have a very fast response time -
there was no need to be specific exactly what material the thin film was.

[John Fields]

On Thu, 7 Feb 2013 20:54:23 -0000, "Ian Field"

---
Identifying the materials was necessary in order to show you that
PTC's can't be PIR sensors, and vice versa.

Whether a thin-film PTC thermistor can have a very fast response time
is irrelevant when the discussion is about PIR sensors so, as usual,
you're befuddled.

On the one hand, consider the PTC thermistor you described and, on the
other, a PIR sensor.

The PTC thermistor is designed to have its resistance increase
spectacularly as it self-heats because of small changes in the current
through it, while the PIR sensor is designed to generate a miniscule
charge when the temperatures its elements are exposed to change
abruptly, ergo apples and oranges.

--
JF

[Ian Field]

"John Fields" <jfi...@austininstruments.com> wrote in message

news:9d58h81gtrnkd2dm9...@4ax.com...

Wriggle wriggle!

[John Fields]

On Thu, 7 Feb 2013 22:05:17 -0000, "Ian Field"

---
In which way?

--
JF

[Ian Field]

"John Fields" <jfi...@austininstruments.com> wrote in message

news:pptah8t3j72uqpv44...@4ax.com...

Any which way it takes when caught out.

[John Fields]

On Fri, 8 Feb 2013 22:16:55 -0000, "Ian Field"

---
I merely point out your errors, and since you were caught out as not
knowing the difference between a thin-film thermistor and a PIR sensor
and not knowing that a Fresnel lens isn't just for use with IR, it
seems you're the one doing all the wriggling when what you should be
doing is thanking me for smartening you up a bit.

--
JF

[Ian Field]

"John Fields" <jfi...@austininstruments.com> wrote in message

news:poubh85q6ulf4chg9...@4ax.com...

They can both be thin film - a point you're too thick to get!

> and not knowing that a Fresnel lens isn't just for use with IR

This is a copy/paste of what I typed: " Freznel type lenses (special IR
>>>>>>>>>> transparent material) "

Being "Freznel type lenses" they're obviously based on something that
existed before PIR sensors. - the more you wriggle - the more you have to be
disingenuous about what I actually said.

You're even too thick to snip what I actually said, so everyone can see
you're making it up the things I never said!

[John Fields]

On Sat, 9 Feb 2013 14:49:03 -0000, "Ian Field"

---
Ah, but that wasn't the point.

Since you wrote:

"If you mean PIR motion detectors, they usually have twin element

pyrometers (thin film thermistor)"...

The point was that that clearly indicates you thought PIR elements
were thermistors, which they never were, aren't, and probably never
will be.

I could be wrong, of course, and if you can provide an example of a
thermistor being used as a PIR motion detector, I'll be happy to
concede the point.
---

>> and not knowing that a Fresnel lens isn't just for use with IR

>This is a copy/paste of what I typed: " Freznel type lenses (special IR
>transparent material) "
>
>Being "Freznel type lenses" they're obviously based on something that
>existed before PIR sensors. - the more you wriggle - the more you have to be
>disingenuous about what I actually said.

---
Disingenuousness has nothing to do with it, since it's all about
getting to the unvarnished truth and pointing out your errors.

For example, you wrote:

"Freznel type lenses (special IR transparent material)"...

which, if you're at all familiar with the English language, implies
that _Fresnel_ lenses are made from IR transparent material.

They're not, of course, in every case, and now that you've had ample
time to do your homework you come back pretending to have known then
what you've only found out now.
---

>You're even too thick to snip what I actually said, so everyone can see
>you're making it up the things I never said!

---
More wine, m'sieur?

--
JF

[Ian Field]

"John Fields" <jfi...@austininstruments.com> wrote in message

news:dkbdh8tjts7qig750...@4ax.com...

One of the PIR sensor datasheets I read described them as such, It was many
years ago that I worked for the alarm company that made the PIR alarms, I
can't remember the part number and I've no idea if I still have those old
datasheets.

But at least I've had actual hands on industrial experience - and not just
swinging through the trees beating my chest.

[John Fields]

On Sat, 9 Feb 2013 22:21:34 -0000, "Ian Field"

<gangprob...@ntlworld.com> wrote:

>
>
>"John Fields" <jfi...@austininstruments.com> wrote in message

>news:dkbdh8tjts7qig750...@4ax.com...

>> ---
>> Disingenuousness has nothing to do with it, since it's all about
>> getting to the unvarnished truth and pointing out your errors.
>>
>> For example, you wrote:
>>
>> "Freznel type lenses (special IR transparent material)"...
>>
>> which, if you're at all familiar with the English language, implies
>> that _Fresnel_ lenses are made from IR transparent material.
>>
>> They're not, of course, in every case, and now that you've had ample
>> time to do your homework you come back pretending to have known then
>> what you've only found out now.
>
>
>One of the PIR sensor datasheets I read described them as such, It was many
>years ago that I worked for the alarm company that made the PIR alarms, I
>can't remember the part number and I've no idea if I still have those old
>datasheets.

---
Convenient.
---

>But at least I've had actual hands on industrial experience - and not just
>swinging through the trees beating my chest.

---
About 11 years ago I took on a project to design and build prototype
quantities of a battery-operated, programmable, video camera based
outdoor wild animal recording system.

Of necessity it required a long-range PIR sensor to wake up the system
and start recording the animal's activities while in view, and I
successfully executed that design, including the optics and
electronics.

Therefore, your claim that I have no industrial experience is
baseless, and instead of my swinging through the trees beating my
chest, your posting history smacks of that it's much more likely you
sit in front of a monitor beating your meat.

--
JF

[The Daring Dufas]

You helped the DEA catch a lot of pot growers. ^_^

TDD

[Jim Thompson]

Ian worked for an alarm company alright... sitting in front of a
monitor in a call center making cold calls trying to sell crap alarm
systems... and believed the boilerplate he read off a script.

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

[John Fields]

---
OUCH!!! :-(

--
JF

[The Daring Dufas]

A friend of mine worked for a local company that put together custom
built electronics for a lot of different customers back in the 1980's.
One of the projects was taking off the shelf video cameras and recorders
built into a weatherproof package with a magnetic detector to video any
unauthorized vehicles visiting coal mine sites. Law enforcement was also
a customer for the item including another variation built into a fake
pole mounted power transformer to be mounted outside the home of any
sort of suspect. An anonymous unsuspicious bucket truck comes out and
mounts the setup which actually draws power from the power line so
there are no batteries. Makes you kind of wonder what sort of hidden
cameras the spooks have hidden around your town. ^_^

TDD

[Ian Field]

"John Fields" <jfi...@austininstruments.com> wrote in message

news:tjifh89fpki5rdafu...@4ax.com...

So that explains your confused ranting!

[John Fields]

On Sun, 10 Feb 2013 17:37:08 -0000, "Ian Field"

---
You have enough first-hand experience with marijuana to substantiate
that claim?

--
JF

[UltimatePatriot]

I think he just did the same thing most (if not all) pigs do.

[Uncle Steve]

Cell towers are ubiquitous in some areas; on buildings, towers, etc.
I wonder if it is possible that 'dummy' antennas could operate as
tempest monitoring stations. But otherwise, the degree of electronics
miniaturization that has occurred means that it should be possible to
manufacture spy-enabled passive components that could be relatively
easily substituted in just about anything, and remember that things
like TVs and such never really turn off.

I worry less about video surveillance than audio, but MEMS devices
will eventually advance to the point where microscopic bugs will be
able to crawl or fly into a residence and set up a fairly
comprehensive spying network. All of which is an NSA/CIA wet-dream
scenario, so they're probably working on it.



Regards,

Uncle Steve

--
More than a century has passed since science laid down sound
propositions as to the origins of the universe, but how many have
mastered them or possess the really scientific spirit of criticism? A
few thousands at the outside, who are lost in the midst of hundreds of
millions still steeped in prejudices and superstitions worthy of
savages, who are consequently ever ready to serve as puppets for
religious impostors. -- Peter Kropotkin

[The Daring Dufas]

I buy gear from Supercircuits Inc. and there are all sorts of covert
cameras you can by from them. Good grief, the cameras in cellphones are
so tiny you would expect them to be available as components to build any
sort of surveillance system. The stuff Supercircuits sells would have
been science fiction not that many years ago. ^_^

TDD