Simple cheap alarm design.

[patrick_g]

Patrick,
You ideas are hilarious. The first item made me smile but the final two had me laughing outloud. Especially the part about the hellicopters.

Remember RADAR O'Reilly on the TV series, "MASH?" Well those dogs were similar. They would start getting antsy before anyone else heard the choppers.

"Gee dear, I don't know whey the dogs hate choppers so much, maybe there is something special about the sound of the chopper that they don't like!"

Meanwhile, the dogs are experiencing the equivalent of having a steam whistle go off inside your head but at frequencies people can't hear.

I have always thought deer could be deterred with ultrasonics but never had enough incentive to set up an experiment. If you put out enough ultrasonics just above human hearing say 25-30KHz you could run the volume up till you melted their antlers and they would try to make it to the next county but people would not hear a thing.

Of course there is always the possibility for collateral damage. The Racoon and Opossum's local union reps or their PETA fellow travelers might have a hissy fit along with any nearby dogs, cats, many birds, etc.

Pat

 

[Soundguy]

That circuit will sure be robust.. but very 'party'.. lots of contacts to wire in.. but heck.. it's clean and it works... what can ya say?

soundguy

 

[patrick_g]

That circuit will sure be robust.. but very 'party'.. lots of contacts to wire in.. but heck.. it's clean and it works... what can ya say?

soundguy

Well... I guess I can say, I'm not sure what contacts to which you refer. Any multi sensor alarm system has to have sensors for all protected doors, windows, etc.

If you refer to the relay, then well maybe there is a simpler way with one less pole but I went with what instilled confidence in me.

On the topic of the relays... If the siren is a heavy current user then maybe wiring another relay coil in place of the siren would be a good idea. Then contacts on that "buffering" relay could switch power to the siren. This will not be required if the siren's current draw does not require a heavy duty (read expensive) relay in the original posted circuit (on yellow ruled paper.)

There is something to be said for a system that will survive a near miss from lightning (or atomic weapons.) Several years ago a pilot defected and flew his shiny new Russian fighter to Japan. US personnel scrutinized the technology and many of them were amused to see all the miniature electronic TUBES in the systems instead of transistors. Lots of guffaws and there was talk about it being a ruse, a specially prepared trick to fool us into thinking they were backward in electronics.

Well the "real deal" was that their avionics were designed to not be crippled by the giant electromagnetic pulse from a thermonuclear weapon. Solid state junctions are fried by a strong EMP but tubes can survive. The Russians were building fighter aircraft that could fight during a nuclear exchange. Ours would not. Sobering isn't it.

Back to the alarm stuff... I don't know when thermal delay relays were first used in decent numbers but I saw them in instrument flying trainers (simulators) in the early-mid 60's (designed in the 50's) The parts you will buy today with the designators of say... 12NO120 or 6NC30 which are respectively a 12 volt operated thermal delay relay with contacts that close 120 seconds after power is applied and the other is a 6 volt powered unit with contacts that open up after 30 seconds, may not in fact be "old" technology. They may be pin compatible solid state substitutes. Time was when you could buy solid state substitutes for many common tubes (valves for you Anglophiles.)

This alarm could have easily been designed with solid state components. Signetics type 555 and 556 timer chips and a hand full of SSI chips and discretes would do the trick with ease ..B..U..T.. It would:

1. be harder for a non-ET to understand
2. not be as much fun
3. not be as lightning proof

Pat

 

[Soundguy]

Don't get me wrong.. I wasn't berating the design.. I like robust designs. It's just one with , depending on how many legs and doors.. etc. you have.. especially bypass or delay ones.. that the system is getting pretty big with lots of relay work.. nutting wrong with that though. Ditto ont he buzzer / buffer relay... lets you drive a real big one.. perhaps blinking lamps too!

soundguy

 

[patrick_g]

No problemo, SoundGuy, I just wasn't sure of your reference.

Should require only one delay relay for all delayed alarm ingress doors but nothing bad if you delay all doors unless you worry about home invasion while you are there and then there are bigger problems.

Surprisingly, no one squawked about the original drawing even though as shown there was no exit delay and you would have to have the controls outside the alarmed space or only use it with the space occupied.

As far as complicated wiring goes, the professionally installed system in our new house has the sensors in series parallel strings. Way too many sensors for reasonably available panels. So groups of sensors are wired in series. then the several groups each go to a single circuit at the panel. Of course the glass breaks and motion detectors are not bundled with windows and doors. This way you can leave a window open and still set the alarm. relying on the motion detector in that area to catch an intruder.

One of the best features of our system is the cell phone module which keeps the system monitoring capability intact even if the phone line is cut. That and the contacts they provided me by my request so I can trigger any action in tandem with the sirens. Like my truck which pages me if the alarm is activated, so can the house. This is not through a regular pay for play pager but direct from a transmitter module triggered by the panel to call the pager.

I thought about opening a valve to a 80CF aluminum scuba bottle (super noisy) and then playing a recorded message over the whole house intercom, "You have been exposed to a colorless, odorless, and tasteless poison gas. after you turn yourself into the police have them contact (phone number) for antidote information. You have about 30-45 min." Of course the message would be in idiomatic Spanish as well as English.

Pat

 

[Soundguy]

All this talk of alarm designs got me to thinking.

If our justice system weren't so lax on property crimes and personal rights of victoms.. and they would just let you execute each and every thief you catch.. my guess is there would be less need for things like this.

.. oh sorry.. I must have been daydreaming again!

soundguy

 

[Egon]

"You have been exposed to a colorless, odorless, and tasteless poison gas. after you turn yourself into the police have them contact (phone number) for antidote information. You have about 30-45 min." Of course the message would be in idiomatic Spanish as well as English.

Throw in a Halon system that dumps.

 

[rebb]

Pat,

i never said nuthin' bout the original design 'cause it was perfect for my application-the garage doors, i figured would be the last thing they hit, as the windows are much easier to break and crawl in through first...especially the offside to the house one-i get about as much lightning and storms as you prolly do, also-flimsy don't cut it around my place. the delay switches are jsut an added bonus in case they happen to get in a window without breaking a wire. actually, the first one in is gonna open the service door for the rest of them, anyway, and break that wire, chances are....

did i tell you the little 102 db piezo alarm i bought is way loud? i'm trying to find a small flashing led that would serve as a visual for my def neighbor (lol!). the other alarm came in-weather proof, and also loud, but in a different frequency range...good karma...

the russians aren't stupid at all. lol! some western systems are not 'genius' in action; we are so over-dependent on a very vulnerable internet and off shore parts...hmmmm....lol! i recall being at work one day, when everything went down...some poor fool backed his backhoe into the main electric station; fried him, killed everything except the traffic lights...we got sent home...the 'human sensing toilet flushers' wouldn't work either (why do we need those again?)

simple works...fancy sometimes don't.
reb

 

[patrick_g]

SoundGuy, Egon, Rebb,

All good comments, guys.

SoundGuy, I think there should be a Citizen Law Enforcement Lisc. You take some classes and pass some written and practical demonstration tests and procure a Government approved weapon with built in cell phone, GPS, and video feed off the telescopic sight.

You will have studied under what circumstances you may collect a bounty, the gun sight documentation video required to substantiate the shoot and such. You are then free to collect the going head price on drug dealers, muggers, and such. Home invasion, carjack, mugging, theft, etc would take a dip in the statistics. It would be a self limiting part time job as the more people who did it the fewer opportunities to do it there would be.

Egon, I converted a Halon system with a glass ampule which boiled and broke at the desired "detection" temp to system with a manual override. I put a small stainless steel cable around the glass vial. I provided a handle to pull to tension the cable which broke the glass vial releasing the Halon. I put a safety pin with a red flag in the handle mechanism to prevent accidental discharge.

This was in a Helicopt Hut, an environmental enclosure used by the military. It fit in the bed of a deuce and a half and had lifting eyes for helicopter transport. They are used for all sorts of things. One of the ones I customized for the Army to be used at Ft. Irwin (the Army NTC, National Training Center, for desert warfare) contained a computer controlled microwave spectrum analysis system I put together. One of the parts of the system was a 12.5KW Onan diesel genset sitting atop a custom fuel tank I designed. I felt better giving the two operators a Halon system.

Rebb, I have used alligator clips attached to nails on window frames before as sensors. You can't get through the window without knocking a wire off and setting off the alarm. These were temporary and so corrosion was not an issue.

Pat

 

[Soundguy]

You know.. if they just offered a bounty on any crooks head.. it might start to self limit too.. I bet crooks would start turning in other crooks!

soundguy