ee5391aa@hydra.unm.edu (Duke McMullan n5gax) (11/25/89)
Yew electronickers out there take notice -- this might be useful.
Prices on infrared motion-sensor outdoor lights have dropped down to the
$15 (sale) level here in Albuquerque. I picked one up back when they were
stable at $17 (Price Club) and took the controller apart to play with it.
The meter probes showed about 16VDC running around in there, and subsequent
experimentation had the thing working just fine on 12VDC.
Of course, the triac was no longer in the circuit (hard to turn off on DC) and
the 110VAC->16VDC circuitry was bypassed, but placing an LED in place of the
optocoupler made for handy experimentation.
I'm convinced that we have here the basis for a hard-to-defeat (hard-to-de-
tect, even) space alarm. You have to have a unit which has a sense position
that isn't shut down in daylight, but all the ones I've worked with (all two
of them) had that capability.
Replacing that LED with a resistor and the base of an NPN transistor, and put-
ting a 12VDC relay in the collector circuit gives a handy combination: I'm in
the process of mounting that in a box. A modular motion-sensing switch, which
runs on 12VDC and can be moved around quite conveniently, offers possibilities
to me. A sensor for wildlife photography, a coyote scarer, a portable trail or
road "eyeball",...the mind boggles.
I think I'll take it down to the next cavers' regional get-together, and put
it in the camper on my truck, driving a Radio Schlock 49-489 piezo siren.
That's one LOUD siren, folks. Check it out.
Think about it. What would YOU do with such a device? Tell the net. We're
listening....
Click, click, ZAP!
d
Give the gift that keeps on giving...a female kitten.
Duke McMullan n5gax nss13429r phon505-255-4642 ee5391aa@hydra.unm.educraig@oakhill.UUCP (Craig Shaw) (11/27/89)
>Prices on infrared motion-sensor outdoor lights have dropped down to the >$15 (sale) level here in Albuquerque. >I ... took the controller apart to play with it. > ... >I'm convinced that we have here the basis for a hard-to-defeat (hard-to-de- >tect, even) space alarm. You have to have a unit which has a sense position >that isn't shut down in daylight... > ... >A modular motion-sensing switch, which ... > offers possibilities to me. >A sensor for wildlife photography, a coyote scarer, a portable trail or >road "eyeball",...the mind boggles. > ... >Think about it. What would YOU do with such a device? Tell the net. We're >listening.... I've experimented with such a beast, in hopes of concocting an outdoor detector, to inform me when someone comes into my yard or driveway. The unfortunate and insurmountable problem arises when it's partly cloudy outside. Every time the sun is covered/uncovered by a cloud the output is triggered. The sun can heat large areas very rapidly, and this looks like lots of motion to this type of detector. Mine generated false indications every few minutes on partly cloudy days this summer in Texas. Works fine at night though. I guess I'll have to use IR source and receiver in a fixed beam system. The big problems there are wiring it far from the house, and disguising it. If IR is used, lenses are a problem and alignment is difficult. With visible LEDs, it may be seen at night, unless a very low duty cycle pulse train is used. Sign me - Back to the Drawing Board. -- Craig D. Shaw - MCU Systems Design (512)891-2245 Motorola Inc., Austin, TX.
brian@ucsd.Edu (Brian Kantor) (11/28/89)
IR sensors for alarm systems are often available in a version which does not operate its signalling contacts until it has been tripped multiple times. That is the kind we have around here; they do trip when people walk past them but do NOT trip from glints of sunlight off windshields, flashbulbs, etc.
dag@hp-lsd.COS.HP.COM (David Geiser) (11/28/89)
"'Coons in the garbage can" detector. Now, what to scare them with?
craig@oakhill.UUCP (Craig Shaw) (11/28/89)
In article <10190@ucsd.Edu> brian@ucsd.edu (Brian Kantor) writes: >IR sensors for alarm systems are often available in a version which does >not operate its signalling contacts until it has been tripped multiple >times. That is the kind we have around here; they do trip when people >walk past them but do NOT trip from glints of sunlight off windshields, >flashbulbs, etc. The original post referred to security lighting sensors, at $15 - $17. True, alarm system sensors are more reliable since most incorporate pulse count techniques. They are also more expensive (if you find one for less than $45 let me know!). None that I have seen seem sufficiently weatherproof either. The false alarms will probably still be a problem with partly cloudy conditions. The sun may be gradually uncovered (over a period of several seconds) and could provide several pulses to trigger the sensor. Failure to trigger is also a potential problem if furry animals are to be detected when the climate/setting provides a background radiation level similar to the animal's. This is less likely to be a problem for larger animals, but could be very significant for animals the size of cats and smaller. My cat has never managed to set off my alarm system, even though the IR detector beams extend to the floor. The PIR detector I have is not of the pulse count variety, hence it should be more easily triggered. Furthermore, the PIR manufacturers warn installers to be sure the detection area doesn't cover windows, because they are prone to rapid solar heating. Also, motion outside might be able to set off the alarm. Finally, if anyone can describe a commercial product (at any price) that uses passive infared detection to detect people or animals during the DAYTIME, I will be interested to hear about it. The only reason this technology works on lighting controllers is that they only need function at night, and failure to operate is not a big deal. Sign me - Still Looking. -- Craig D. Shaw - MCU Systems Design (512)891-2245 Motorola Inc., Austin, TX.
ee5391aa@hydra.unm.edu (Duke McMullan n5gax) (12/01/89)
In article <7600031@hp-lsd.COS.HP.COM> dag@hp-lsd.COS.HP.COM (David Geiser) writes: >"'Coons in the garbage can" detector. Now, what to scare them with? Dave, let me call attention to the Radio Schlock piezo siren I mentioned in the original post. For size, etc., the little bugger is AMAZINGLY loud. d Give the gift that keeps on giving...a female kitten. Duke McMullan n5gax nss13429r phon505-255-4642 ee5391aa@hydra.unm.edu