Re: diy microwave alarm

[Jim <alarminex@xxxxxxx>]

On Monday, May 5, 2014 7:13:42 PM UTC-4, joe hey wrote:
> On Mon, 05 May 2014 11:26:59 -0700, Jim wrote:
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> > On Saturday, May 3, 2014 8:40:12 AM UTC-4, joe hey wrote:
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> >> On Sat, 03 May 2014 09:18:50 +0000, joe hey wrote:
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> >> > On Sat, 03 May 2014 09:17:25 +0000, joe hey wrote:
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> >> >> On Sat, 03 May 2014 01:28:52 -0500, G. Morgan wrote:
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> >> >>> joe hey Wrote:
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> >> >>>>On Fri, 02 May 2014 14:11:30 -0500, G. Morgan wrote:
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> >> >>>>
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> >> >>>>> joe hey Wrote:
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> >> >>>>>>(What is a 'PE beam'?)
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> >> >>>>> Photo-electric
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> >> >>>>
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> >> >>>>PE beams would be fine if they could span about 200 m in heavy
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> >> >>>>rain.
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> >> >>> You would need an array, and if CCTV breaks the budget than PE
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> >> >>> beams
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> >> >>> are out of the question.
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> >> >> oh, my bad, I thought CCTV would just be more expensive than PE.
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> >> >> After all, I thought, PE is just an infrared emitting diode on the
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> >> >> one,
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> >> >> and a receiving photo diode on the other side.
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> >> >> But maybe this is something useful?
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> >> >> http://www.aliexpress.com/item/P92-Wired-250M-Alarm-Triple-Beam-
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> >> >> Photoelectric-Infrared-LED-Detector-Tamper-Alarm-
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> Output/1011069523.html
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> >> >> It would only require 6 of those sets to cover al sides...
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> >> >> Totalling about $380, wiring excluded!
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> >> > Oh, and solar panels for power, batteries for during the night.
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> >> > And then have it all stolen one night...
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> >> Forget the last remark. All units can be series-fed through one curren=
t
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> >> source that's on a protected location and I'm sure an 'alarm voltage
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> >> pulse' can be put on the feeding line which will be seen at the source
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> >> which then would be able to ignite the alarm.
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> >> I found this 'DIY' project.
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> >> http://www.electroschematics.com/782/infrared-light-barrier/
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> >> Double-modulated beam. With a bit of logic it can be made multi-beam,
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> >> different frequencies, and such that the alarm goes off only when all
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> >> beams are interrupted.
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> >> I wonder if this can be equipped with laser pen-style laserdiodes, so
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> >> that a high distance can be reached.
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> > Laser pen diodes are in the visible light spectrum. You'd want somethin=
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> > in the infra red range.
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> > But .... I still think you're going to spend a lot more money (and
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> > certainly time)  developing this Rube Goldberg device than it would cos=
t
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> > to just go out and buy it. I know one thing that you haven't even
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> > considered and that is alignment of the beams. You're thinking it's
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> > going to be easy ..... (HA!)  And don't kid yourself ..... there ARE
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> > going to be lots of false alarms regardless ..... and MORE of them if
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> > you design it. You've got to guess that the manufacturers of these
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> > devices didn't just think up the idea, put the device together and it
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> > worked the first time. Outdoor sensors take years to develop and refine
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> > and even then they are prone to false alarms.
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> > But ...... you sound like you're on a mission to prove something ....
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> > so be it. Good luck.
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> Actually I'm not. I'm just trying to explore the options we have.
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> And yes, I did consider alignment of the beams of a laser pen and think=
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> it's nearly impossible to do that right. Even if taking some very sturdy=
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> concrete posts, put them 4 m deep in the soil for stability, attach=20
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> strong steel sockets around them holding the mirrors while using fine-
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> threaded screws to adjust them.
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> Keeping them aligned, or even clean after a rain without destroying the=
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> adjustment, will certainly be near to impossible.
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And yet you still want to try to design and build one yourself?


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> 'Just go out and buy it'? : X6, that's the problem :)
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> thanks

Well then ... let's try it this way ...... how much do you think it would c=
ost you to make a device yourself? How many hours are you prepared to spend=
 experimenting? How long do you think it will take you to produce a viable =
device? How many strawberry seasons are you willing to sacrifice before the=
 unit works to your satisfaction? What will you have gained if you never (l=
ikely) get it to work properly? What will you have lost? =20

Unless you're not telling us all the details .... with the information at h=
and so far ..... well ... I won't say it again but .... you know what I'm g=
oing to say .....=20

And ........ I really think that even with a professionally manufactured de=
vice, you'd still have an unreliable system. Outdoor sensors are just .....=
 plain and simple ... unreliable.=20

How about some good watchdogs with one of those electronic dog fence thingi=
es and collars? You'd just have to be sure the dogs are meat eaters and not=
 vegetarian.