A different kind of motion sensing security light?

Page 1 of 3  
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.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
John Doe wrote:

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&cvsfa961&cvsfe=2&cvsfhuC4f4d2d303738&gclid=CJ2d-vabmbUCFUid4AodwxIAIg
Jamie
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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 /
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
"Tim Williams" <tmoranwms charter.net> wrote:

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.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 2/3/2013 1:41 AM, John Doe wrote:

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
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 2/3/2013 9:16 AM, snipped-for-privacy@optonline.net wrote:

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.
Cheers
Phil Hobbs
--
Dr Philip C D Hobbs
Principal Consultant
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Most of the examples I pulled apart and hand traced the circuit years ago, were based on the LM324.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Sun, 03 Feb 2013 01:55:03 -0500, 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.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Tim Williams wrote:

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Feb 3, 8:17am, snipped-for-privacy@eskimo.com (Mark Zenier) wrote:

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.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Ian Field wrote:

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
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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

if you could make it thin enough it would work.
--
⚂⚃ 100% natural

--- news://freenews.netfront.net/ - complaints: snipped-for-privacy@netfront.net ---
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

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.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Wed, 6 Feb 2013 16:42:04 -0000, "Ian Field"

--
Apples and oranges.

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload


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.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
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.
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload


Wriggle wriggle!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Thu, 7 Feb 2013 22:05:17 -0000, "Ian Field"

--
In which way?

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.