# yet another improvised perimeter alarm



## tinkerhell (Oct 8, 2014)

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## tinkerhell (Oct 8, 2014)

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## tinkerhell (Oct 8, 2014)

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## tinkerhell (Oct 8, 2014)

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## thepeartree (Aug 25, 2014)

tinkerhell said:


> my goal here is to imitate this very cool and awesome product: Dakota Alert Wireless Security Equipment
> 
> Here is my version:
> 
> ...


I would add that old phone wire makes an excellent wiring link in this project. It would be nice if you could buy/salvage a red led laser for this project!


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## tinkerhell (Oct 8, 2014)

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## thepeartree (Aug 25, 2014)

tinkerhell said:


> Basic description of alarm:
> 
> The passive infrared sensor is used to detect a *change* in infrared in the zone that it is monitoring. When someone or something ( usually a person) enters the zone, the sensor will output a high voltage which travels down the cable and turns on the LED. What you do with this knowledge is up to you. There is no loud siren, no auto dialer, no wireless transmission, no key board to arm and disarm this alarm.
> 
> ...


UNLESS you want the thing to activate an alarm. Then I suggest using the output to activate a relay and let the heavy power go through the relay's wiring.


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## tinkerhell (Oct 8, 2014)

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## thepeartree (Aug 25, 2014)

tinkerhell said:


> What would you use the laser for, an indicator?


I'd use it to send the signal to a photo receptor a lot closer to home. Similar circuit to what is described above, but switches more power through a relay to run an alarm. I don't like the idea of an alarmless alarm. A red led just isn't enough in a shtf situation, so use the detector output to relay the detection through the laser.


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## tinkerhell (Oct 8, 2014)

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## tinkerhell (Oct 8, 2014)

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## tinkerhell (Oct 8, 2014)

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## DoubleA (Nov 9, 2012)

Subscribed. I'm an electronics dummy, this simple approach fas a definite appeal. Please keep the good ideas coming.


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## Deebo (Oct 27, 2012)

Lov it


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## A J (Oct 16, 2014)

Very nice, I was looking at the Jameco site and they have another sensor almost identical except it is a wide angle (180 degree). 
Should be usable in same circuit.

Any idea what the angle on this sensor would be?

AJ


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## tinkerhell (Oct 8, 2014)

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## MrsInor (Apr 15, 2013)

Sometimes you read very carefully through a thread - get to the end - and realize you didn't understand a word of it.
Maybe after another glass of wine.


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## tinkerhell (Oct 8, 2014)

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## thepeartree (Aug 25, 2014)

tinkerhell said:


> I see what you are talking about. That would definitely be an excellent improvement. I think it will require some more design and testing because as you kbnow, a sensor designed to detect visible light( ie a laser) will also see ambient light. The ambient light will be a source of noise and interference. You may have to modulate the laser, then - at the detector side - filter the signal with a band pass filter.
> 
> This is a cool project and would be fun to get involved with.


I think it's possible to get a detector that is built to see only a laser. I know it exists, the only issue could be cost. They sell them to people who use them on surveyors' range rods. The laser hits the detector and turns on a red led and optionally a buzzer (momentary). What I suggested was the same thing, except the laser is part of the alarm, rather than the initiator. It just means you could set up 3 of these and get an entire camp perimeter as far away as your line of sight allows. Whole thing should run days, mini.um on a set of batteries.


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## tinkerhell (Oct 8, 2014)

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## tinkerhell (Oct 8, 2014)

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## thepeartree (Aug 25, 2014)

I think that it's a valid concern, both for my suggested alteration AND the original. I admit that I was thinking more along the lines of a real perimeter guarding system. That would mean continuous laser use, but since it's something that can protect a really long piece of perimeter, you'd want to make dam sure that you fixed it in place. Lets all add a fistful of 12" zip ties and a roll of gorilla tape in our bobs. The electronic boxes (as I'd assume) should be waterproofed, if at all possible. Once you throw in gorilla tape, you should expect to be able to put it in place and have it stay. But, you face the threat of intelligent tampering. So I feel that an 'always on-interrupt to sound the alarm' is the best method. That way if ANYTHING screws with it you get an alarm. I admit that you could keep a bunch of rechargeable batteries busy, but you have the best available secure perimeter. It's better than a watchdog or a human version. It never gets tired, sick, bored, or sleepy.


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## thepeartree (Aug 25, 2014)

But... look here-> CAPSS3? Camp Alert Perimeter Security System.


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## Old SF Guy (Dec 15, 2013)

tinkerhell said:


> if the laser only turned on during an intruder event, it could be knocked out of alignment by the wind, etc and you would have no way of knowing. however, at the expense of a continuous drain on your batteries, you could make it shoot a continuous beam at your detector, and the absence of the beam would indicate an intruder.
> 
> or design it for both?


Tinker that would be an excessive battery drain I think...as to having a battery near the PIR vice at the LED location. You could get several of the solar charging sidewalk lights...remove or disconnect the lights, bury them down so that just the solar panel is a ground level and wire them in a fashion to get the voltage.With two you should get about 6 volts and then step it down to five.(in all honesty I am not sure what the actual voltage is for these lights). This would get you a self sustaining power source for quite awhile. You could add more in series and parallel to increase the amp hours and make it last longer.

Good post thanks.


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## thepeartree (Aug 25, 2014)

Old SF Guy said:


> Tinker that would be an excessive battery drain I think...as to having a battery near the PIR vice at the LED location. You could get several of the solar charging sidewalk lights...remove or disconnect the lights, bury them down so that just the solar panel is a ground level and wire them in a fashion to get the voltage.With two you should get about 6 volts and then step it down to five.(in all honesty I am not sure what the actual voltage is for these lights). This would get you a self sustaining power source for quite awhile. You could add more in series and parallel to increase the amp hours and make it last longer.
> 
> Good post thanks.


I can answr some of your questions. Those solar path lights actually have >1< AA size 1.32volt battery in them, trickle charged by the solar panel. Now, if you have the panels at ground level, do you know what happens when it snows? Right. No light. Or in this case, no alarm. Same for when the batteries run out at night. They do, you know. They only power one small power led and the battery runs it for about 5 hours, ideally. I know these things because I took a close look at several that fell apart during the first winter storm after installation.


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## tinkerhell (Oct 8, 2014)

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## tinkerhell (Oct 8, 2014)

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## Old SF Guy (Dec 15, 2013)

thepeartree said:


> I can answr some of your questions. Those solar path lights actually have >1< AA size 1.32volt battery in them, trickle charged by the solar panel. Now, if you have the panels at ground level, do you know what happens when it snows? Right. No light. Or in this case, no alarm. Same for when the batteries run out at night. They do, you know. They only power one small power led and the battery runs it for about 5 hours, ideally. I know these things because I took a close look at several that fell apart during the first winter storm after installation.


Thanks for the info on the solar lights. Maybe not the best way to power it then...


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## Old SF Guy (Dec 15, 2013)

tinkerhell said:


> just a little side post explanation on LED for techie geeks like me.
> 
> LEDs require a specific voltage to light up. There are some LEDs that light up quite nicely with a 1.5V laser pointer battery, and there are some that light up quite nicely with a CR2032 3.2Volt watch battery.
> 
> ...


I get the LED voltage issue, but I thought the bigger problem is powering your sensor, which I understood to need 5 volts. If you can reliably power that then the voltage for the LED is really taken care of...correct? And what is the actual delivered voltage from that 5 volts after it has run through a line of "oh let's say' 100 yards? I'm sure there is a math equation that you would use to calculate for line loss....damn where's paul when you need him....

OK found it.. a loss of about 18% over 100 yards, 25% over 100 yards, 37.7% over 300 yards. At 300 yards a 5V source will still deliver 3.1V to the LED given 16 gauge wire. If the site I was viewing is correct.


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## tinkerhell (Oct 8, 2014)

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## Old SF Guy (Dec 15, 2013)

tinkerhell said:


> True, the resistance of a copper wire over 100 feet is not a theoretical zero ohms and it varies based on the wire gauge. Something like a 28 AWG wire will drop something like 20mV per yard. 100 feet could be 1 volt loss, but the sensor works from 3V-6V and you could always add a fourth AA battery
> 
> Edit: Also, you have a good point. A power source that can provide for the sensor will be more than sufficient for an LED. The only things that might be more demanding will be a laser but it is beginning to look like the laser would be used in a homestead rather than a campsite so there should be other options available for power.


I guess my concern is that if the input range of the IR sensor is limited to 5 volts and your output run from that sensor back to your LED was such that you needed to add additional voltage to power the LED, then you would have to have the additional Battery on the Output side of the sensor, and not on the input side, unless the sensor has a bypass route that would send the full power of the input power down the line while being able to only have to add the resistance on the sensor operations side.... Did that make any sense to you?


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## tinkerhell (Oct 8, 2014)

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## thepeartree (Aug 25, 2014)

tinkerhell said:


> I don't understand you ( oh, great! Now Im going to get my ass kicked at the next prepperforums summit - lol)
> 
> The way that I drew the circuit, the battery supplies the sensor, the sensor supplies the LED. In theory this will work, but cable losses might make it difficult. Imo, it won't be an issue, because the amount of current required to light an LED is only about 1mA.
> 
> ...


Yes, you still make sense. But let it hinge on the laser. Instead of some "big" industrial laser, you're going to be dealing with an led laser. I have a laser pointer here that runs on 3 button cells... and they're LR44's at that. You can't tell me that an led laser like that pulls much current! So... let's just assume that the laser is not going to be a big issue. P.s. if you want one to play with, head for wally world and throw down $5 or less.


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## tinkerhell (Oct 8, 2014)

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## tinkerhell (Oct 8, 2014)

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## thepeartree (Aug 25, 2014)

We'll see  like waiting for Christmas...


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## tinkerhell (Oct 8, 2014)

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## tinkerhell (Oct 8, 2014)

So, anyway, 1hour and 20 minutes of 'intruder alert' is a workable limitation. Otherwise, some AA batteries could be used. Cheap alkaline batteries have about a 5OOmAh rating with more expensive Nickel metal hurried rechargeables at 2000mAh rating.

This laser could last hrs = .500/.030 which is about 16.5 hours. Multiply that by 4 if you want expensive batteries, puts you over 60 hours of laser time. A setup could have it's batteries charged/replaced once a week, and the condition of the battery would remain excellent throughout the week.


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## tinkerhell (Oct 8, 2014)

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## TacticalCanuck (Aug 5, 2014)

I cant add anything technical as im totally learning stuff here - rock on folks! I think i found a cool thing for the survival tins the scouts are building


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## tinkerhell (Oct 8, 2014)

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## thepeartree (Aug 25, 2014)

The more I think about it, the more I like the idea of a pocket laser as an optical link. By that I mean using mirrors to cover a perimeter or trip wires and then have the beam make the final leg to an optical detector inside or just outside the house. I definitely want the laser, because it has a far greater usable range than any existing regular light beam. Far cheaper, too, and without the need to focus the light. All I want is something to go BEEP! when the beam is no longer shining on the detector. You may get false positives in bad weather, but better that than not catching a real intruder.


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## tinkerhell (Oct 8, 2014)

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## tinkerhell (Oct 8, 2014)

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## tinkerhell (Oct 8, 2014)

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## tinkerhell (Oct 8, 2014)

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## thepeartree (Aug 25, 2014)

What's the shape of the detection zone and the range?


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## A J (Oct 16, 2014)

Very nice, looks like it works just as advertised.

Let us know about any range / angle measurements you do. 

I like the sensor on the tuna can, if that gave 360 degree movement detection that would be great (what angle and range?)

AJ


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## tinkerhell (Oct 8, 2014)

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## tinkerhell (Oct 8, 2014)

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## thepeartree (Aug 25, 2014)

tinkerhell said:


> The circuit board has a sensitivity adjustment. A JUMPER that puts it into night mode or 'All time' mode.
> 
> Also, there is an 'enable' pin, making this a 4 wire connector instead of 3 wire. Ground, Power, and Output. The enable pin is active without connecting it to anything, so a 3 wire cable is very do able.
> 
> By pulling the enable line to ground, the sensor turns off, and it's power drain was not registering on my test bench power supply (ie <1mA)


Hmm. 20 to 30 feet means you're going to need a bunch of them. I would suggest using telephone wire. It has plenty of conductors and is cheap and unobtrusive.

Now that I see your hardware, I can tell you that we bought a couple of security lights with sensors like that. They have very bright led arrays adjustable time on and an on/off/auto switch. It runs on 4 AA's.


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## tinkerhell (Oct 8, 2014)

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## tinkerhell (Oct 8, 2014)

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## A J (Oct 16, 2014)

Question for you.

Will the unit work through a window? 

If it will, it would greatly simplify setting it up quickly inside a house during a time of civil unrest.

I could see having a half dozen of these that you simply set on the window sill to alert you of someone in the area outside the window.

If you get a chance, let me know if that would work, especially if it is cold outside (winter) and heated in the house.

Thanks,
AJ


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## tinkerhell (Oct 8, 2014)

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## tinkerhell (Oct 8, 2014)

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## tinkerhell (Oct 8, 2014)

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