A different kind of motion sensing security light?

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Robert Macy wrote:

A microwave sensor with a F/V converter & the input signal would let him have amplitute & speed. Doppler RADAR measure the frequency difference from the transmitted signal by mixing the echo with the transmitted RF. You have to filter the phase noise for best perfomance, but just selecting the right capacitor for capacitive coupling into the amp will limit the LF response. The amplitude will give you distance, the frequency change will show the speed of the target. You can use the signals seperatly, or mix them for whatever result you want.
You can get the doppler microwave module for $7 and add the rest.
http://www.ebay.com/itm/360556310119
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wrote:

I agree that he has the highest potential of success using microwave, or such. But what you describe is usually AC coupled output and you're back to standing still not showing up. You could DC couple the detector, 'remember' the level coming out when nothing is there, and simply go from there, with a cheap ADC and map back into a DAC that runs the lighting.
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On Sun, 3 Feb 2013 03:28:58 +0000 (UTC), John Doe

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Generally, no.

The common pyroelectric motion sensor outputs a single pulse when the
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John Fields <jfields austininstruments.com> wrote:

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.

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.
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Thanks to the replies.

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On 2/3/2013 5:51 PM, John Doe wrote:

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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
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On Mon, 4 Feb 2013 03:05:37 +0000 (UTC), John Doe

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

Can you post a schematic of the circuit you played with?
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John Fields <jfields austininstruments.com> wrote:

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.
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On Mon, 4 Feb 2013 23:35:40 +0000 (UTC), John Doe

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eternalseptember.org, huh?

Bye.

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John Fields <jfields austininstruments.com> wrote:

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.
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> Bye.
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On Mon, 4 Feb 2013 01:51:54 +0000 (UTC), John Doe

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I've done long-range PIR detection before and 20 feet is pretty easy,
but 100 feet is going to take some care.
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John Fields <jfields austininstruments.com> wrote:

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.
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On Sun, 03 Feb 2013 18:55:42 -0600, John Fields

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Oops...

That's wrong.
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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.

I've not heard of one.

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