Burglar Alarm with EXTREMELY LOUD siren - Page 1
Forum section: electronics / projects

author: Ecklar
author_rank: Regular Contributor
timestamp: October 16, 2016, 11:52:37 pm
content: I am building a burglar alarm system. Yes simple enough, but I want it to be so loud that it's weird, sick and really scary. The thought is to have the room (building) internal siren to be so loud that it shocks and scares trespassers and makes it difficult for a person to think and continue with any action except a desire to flee. I'm thinking of limiting the system to 12 volts so I can run it off of a power supply backed up with 12 volt rechargeable batteries so it will work if main power is cut or generally down; i.e., after a natural disaster like a storm.It seems most available sirens come in around 110 - 120db. Why not 135db? And it would be nice to have a noise source that could project the noise sound pressure such that you'd still get obnoxiously loud sound 100 feet from the source. I want the noise source to be no larger than about 1 cubic foot. The smaller the better so it is as inconspicuous as possible. I'd love to use an old air raid siren, but they seem huge and probably require more than 12 volts.With that in mind do you have any ideas as to what sound source I could use in my alarm system to create a situation that would be difficult and truly shocking for intruders?Thank You

author: rs20
author_rank: Super Contributor
timestamp: October 17, 2016, 12:17:30 am
content: The sheer malice in this question is pretty disgusting. In any case, by my rushed calculations 135 dB SPL @ 1m corresponds to over 40 watts of pure audio power from an isotropic emitter;afterthe inefficiency of the speaker. I can't really think of anything complimentary to say about this statistic.

author: Ecklar
author_rank: Regular Contributor
timestamp: October 17, 2016, 12:22:50 am
content: Quote from: evb149 on October 17, 2016, 12:06:33 amVolcano and magic speakers. Yeah. That's brilliant. I'm asking for the best idea within the limitations or even pushing the criteria a bit if viable. Also, I never suggested that I wanted to fill a auditorium with 10,000 screaming fans. I AM looking for the most obnoxiously loud effective solution ideas to my project. Please, I am looking for ideas I may have overlooked.... not beer talk.Thanks

author: Ecklar
author_rank: Regular Contributor
timestamp: October 17, 2016, 12:31:16 am
content: Quote from: rs20 on October 17, 2016, 12:17:30 amIf by malice you mean an effective way to physically arrest or repel an intruder to save life and property, then yes, that is what i AM seeking. However, I would really appreciate and am looking for a concrete product, device or build solution. I am not trolling for pedantic analysis that goes nowhere.Thank You

author: Ian.M
author_rank: Super Contributor
timestamp: October 17, 2016, 12:56:03 am
content: Compressed gas cylinder with a rupture disk, a carefully designed whistle that works with up to 2000psi input pressure and a solonoid to strike the pin to pierce the rupture disk. With a big enough cylinder to get enough gas flow and a larger whistle and a horn to direct the sound, it would be possible to reach lethal dB levels.Alternatively an array of electrically detonated thunderflashes scattered around the area triggered by a psuedorandom sequencer - think weaponized Vetinari clock!

author: Ecklar
author_rank: Regular Contributor
timestamp: October 17, 2016, 01:10:47 am
content: Quote from: wilfred on October 17, 2016, 12:52:46 amBetter locks stop only children. CCTV deters absolutely nobody. Monitored alarm systems average response time from authority averages 27 minutes. Any ideas on actual physical device solutions greatly appreciated. Please. I am looking for engineering ideas and not tricked out social commentary or beer talk.Thank You Wilfred for your contribution.

author: Ecklar
author_rank: Regular Contributor
timestamp: October 17, 2016, 01:17:59 am
content: Quote from: Ian.M on October 17, 2016, 12:56:03 amI DID consider the air horn but I want to stay as close to 1 cubic foot device dimensions as possible. The horns, compressor and tank to make this work will come out to easily over 5 or 6 cubic feet and I don't believe will run off my 12 V battery backup. If there are some small air horn system I've overlooked, maybe that could be the solution, usually YOU need the compressed air tank and requires more volumetric space than I have.

author: MK14
author_rank: Super Contributor
timestamp: October 17, 2016, 01:21:11 am
content: Quote from: Ecklar on October 17, 2016, 01:17:59 amMy reply (which I just removed), was a JOKE. I did not think you would be crazy enough to consider it.Surely it is against the law where you live ?

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 17, 2016, 01:27:33 am
content: There are automotive air horns that will easily fit in a cubic foot for the whole kit. Other than that, maybe firecrackers?I would also suggest a bunch of Xenon strobes set to flash at 5-10Hz. Such a flash rate is very disorienting.

author: Ecklar
author_rank: Regular Contributor
timestamp: October 17, 2016, 01:33:11 am
content: Quote from: NiHaoMike on October 17, 2016, 01:27:33 amI like the Xeon idea to enhance the effect. Any ideas on which air horns would fit the small space? Somehow either a compressor and compressed air tank would be needed so I am thinking that would push me beyond the 1 cubic foot. Frankly, that is my starting point. A little beyond the 1 cubic would be OK.

author: Ian.M
author_rank: Super Contributor
timestamp: October 17, 2016, 01:37:09 am
content: There's alsohttps://en.wikipedia.org/wiki/Blaster_(flamethrower)Legal in some jurisdictions . . . . .

author: Ecklar
author_rank: Regular Contributor
timestamp: October 17, 2016, 01:44:55 am
content: Quote from: MK14 on October 17, 2016, 01:21:11 amCrazy? When brainstorming, all ideas are worth consideration on an engineering basis. Air horns are illegal for passenger cars, but not necessarily for certain alarm situations if zoning allows and that depends on the local. If the proper alarm could save life and/or property in a non-lethal fashion, I don't think there is anything crazy about that. If you have serious property and people that exist in a dangerous situation and maybe it's your familly, it's perfectly sane to put your best effort into the effort mate.I really didn't know you were joking. I just thought you had no idea for the actual size of the air horn system since I've already evaluated and dismissed it as not feasible.

author: IanB
author_rank: Super Contributor
timestamp: October 17, 2016, 01:48:41 am
content: Loud sounds will only work once. The second time the intruders will come back with ear defenders. If you are in the USA suitable hearing protection is easily purchased from any shooting range or gun shop.

author: MK14
author_rank: Super Contributor
timestamp: October 17, 2016, 01:53:55 am
content: Quote from: Ecklar on October 17, 2016, 01:44:55 amWhen I said "Crazy", I meant it in two different senses.Firstly that to hurt the burglars was a bad idea and could lead to you being prosecuted.But enough about that aspect of crazy for now.The other crazy sense, was that the idea was not very practical (massive tanked air horns and stuff). Such as you mentioning being too big, etc.I've experienced VERY loud conventional sirens (electric piezo/speaker), indoors. They definitely made me want to leave the area. So I think it can be done, with conventional sirens, if placed indoors, and they are the loud variety.They can be relatively cheap (perhaps $10 to $20 or so), small (about 6 inches square, and a few inches deep). Also fairly easy to connect to your alarm system.This is what I think (but maybe a bit louder), was in the last youtube video I linked to above.tl;drAt least for me, it makes me want to leave the area, quickly and not stay there.

author: jonovid
author_rank: Super Contributor
timestamp: October 17, 2016, 02:00:52 am
content: QuoteWhy not 135db? , the Law, your sky high cast of haveing public liability insurance for the permanent hearing damage. or killing someone in a mantrap!you go to jail.So a bank of piezoelectric elements running square wave at 2kHz to 3kHz will cause hearing pain. disorientation, sound perception confusion.a Note that young people'shearingis the full 20 Hz to 20 kHz. & that most breaking and entering is by people under 25 yo. -must be fit so a sweeping 3kHz to 20 kHz at 110db will do.

author: ruairi
author_rank: Frequent Contributor
timestamp: October 17, 2016, 02:01:31 am
content: The owner/user of your proposed alarm system will set it off accidentally and suffer permanent hearing damage. This is a dreadful idea.

author: BradC
author_rank: Super Contributor
timestamp: October 17, 2016, 02:29:05 am
content: Back when I was an apprentice we had a job installing and commissioning a security system for a lovely but eccentric gentleman worth a *lot* of money. He had some innovations like staged wire rope gates on his driveway that would trap intruding vehicles, sequenced floodlights that made the property light up like a disco to alert the neighbours to an alarm and a few other interesting features.In his boathouse/garage he had a very large horn he wanted hooked up. It was rated well in excess of 135dB and consumed an inordinate amount of power. We provided a power source, contactor, terminals and interconnecting cable but politely refused to hook it up or test/commission it. The theory was to cause immediate damage to any intruder. I believe he hooked it up, but we wanted no further part in the endeavour. I don't know where he got it and I never asked.I did some work recently for an LNG plant with an LRAD (Long Range Audio Device) that was rated to provide a painful level of sound at 5Km using a focused beam. Again, not interested in the how or why, just decided I didn't want to play in that sandpit.

author: ez24
author_rank: Super Contributor
timestamp: October 17, 2016, 03:10:07 am
content: Try what the police use, a stun grenade. It works on the principle of sound, so loud it stuns, thus the name. I am sure an electronic activated one can be designed and built. I like the idea. Maybe you would get a fine for using it.They were used at my house to wake people up ha ha ha (they work)

author: helius
author_rank: Super Contributor
timestamp: October 17, 2016, 03:14:16 am
content: Ordinary smoke or CO detectors are unbearably loud when tested up close. These devices are less than 200 cm3and run off 4.5V. They could possibly be extended with appropriate horns to cover a larger area at longer range and still be effective.The issue highlighted by IanB applies: once attackers know that the system is in use, they will use ear protection. I suggest you use multiple modes of action to make the response unpredictable.An electronic noise system can easily emit warning chirps before it goes full blast. Attackers won't know what the warning means, so they won't cover their ears before the alarm activates, but property owners will.

author: DaJMasta
author_rank: Super Contributor
timestamp: October 17, 2016, 03:52:11 am
content: Please don't make it, even if you find a suitable noise maker.The vast majority of alarm soundings will be false alarms or routine tests, and unless you're trying to protect something with no hearing and no people within half a mile or more, there will be hell to pay every time it sounds (provided you can fit such a device into a cubic foot that can fire more than a few times without damaging itself). 110 dB, your basic low end estimate, is enough to cause physical pain in some people and measurable hearing loss with just a couple minutes exposure. 120dB is enough to cause pain in most, instant temporary hearing damage, and long term hearing damage with only 30 seconds or so of exposure - think a nearby thunderclap, working in an active steel mill, or small arms firing close to you. The range you're talking about is akin to the deck of an active aircraft carrier, a gun going off within just a couple feet of your ear, fireworks going off next to you, or an air raid siren in the same room as you. 135dB and thereabouts is enough to instantly do permanent hearing damage, cause significant physical pain, and is nearing the physical breaking point of the ear drum.The alarm WILL misfire, they always do. Sound this loud WILL damage the hearing of anyone within a few dozen yards and piss off anyone for several hundred more. This is enough sound pressure to start picking frequencies and nearby materials carefully because it can damage them, and even if there are no explicit laws against it on the books for your area, you are likely to be sued by any potential invader, if not your neighbors.So yes, it's probably possible to meet your goals, but if you really think it's beneficial to risk so much damage and pain on accidental victims and unprepared criminals..... just hire a security detail, clearly you need something better than an automated system and they will be much more acceptable in your community and much less likely to injure someone you're trying to protect (if the idea really is for protecting a residential property). Please do not implement this.

author: ez24
author_rank: Super Contributor
timestamp: October 17, 2016, 04:50:12 am
content: Quote from: DaJMasta on October 17, 2016, 03:52:11 amHow about use 12ga shotgun shells, take out the buck shot and stuff in a small rag. Then use a small heating coil to fire them off. A few of these going off will cause pee stains on the floor. And probably easier to make than a flash bang grenade. Have a loud high pitch siren that ramps up (I would try 2 sec) and at the peak, have a shell go off. I think this would be pretty nasty.A ramping screaming alarm with explosive sounds - sounds cool. umm Kickstarter timeHere is an idea to get startedIf you are wimpy here is another idea ( 8.6 million views ! )Man can you just imagine this going off with shot gun shells - oh yeah !

author: MK14
author_rank: Super Contributor
timestamp: October 17, 2016, 04:55:38 am
content: Quote from: ez24 on October 17, 2016, 04:50:12 amThere already was a kickstarter project, very similar to how you just described. There was a thread about it here.You have to be careful, otherwise you can be prosecuted for laying down man traps (terminology may vary by country).EDIT:Here it is:https://www.eevblog.com/forum/crowd-funded-projects/bike-mine-a-literal-mine-on-your-bike/

author: Ian.M
author_rank: Super Contributor
timestamp: October 17, 2016, 05:10:33 am
content: Party poppers repacked with finely ground dried Ghost Chillis + a job lot of solenoids to fire them. No hazard to the neighbours, but your burger wont be very happy. Add the 110dB warbling sirens and strobe lights for maximum effectiveness. Personally, if you do experiment with this the first priority would be to develop an effective RFID lockout system for the more vigorous parts of the system so although the alarm can be activated, the nasty bits cant easily be triggered if there is a family member in the room wearing a tag.

author: MK14
author_rank: Super Contributor
timestamp: October 17, 2016, 05:21:58 am
content: Quote from: Ian.M on October 17, 2016, 05:10:33 am[Family Member]I've forgotten my necklace (with built in RFID tag). Better go back inside and get it.Oops I've set the alarm off.Then walks towards the man traps, "nasty bits", WITHOUT the RFID tag.Boom BOOM boom.Broom BROOM brooms to tidy the mess.boo BOO boo, family member says about new alarm system...tl;drI'm not entirely convinced that this is a good/safe/legal idea.

author: Ian.M
author_rank: Super Contributor
timestamp: October 17, 2016, 05:41:36 am
content: Its still kinder than the automatic 'camera' aiming servo I was asked to develop for 'warehouse security' by a somewhat shady client from the Near East with connections to the local dictactorship. I told the client the only way I'd take the job would be if the solution was purely a combination of optics and software processing. He wanted the physical camera pointed with fast heavy duty servos with a high shock rating and spare actuator channels. I said "Not Interested." as I didn't want to build an ED-209.

author: MK14
author_rank: Super Contributor
timestamp: October 17, 2016, 05:47:14 am
content: We probably really will get some kind of property protection robot. In the not too distant future.A USA one, which can fire live bullets at intruders.A UK one, which can shout at the intruders to leave at once, or the robot will cry.All joking aside. I wonder what technology they will invent, to give the protection/security robots of the future "teeth", like a dog.Maybe some kind of very safe electric stun gun or something ?

author: NiHaoMike
author_rank: Super Contributor
timestamp: October 18, 2016, 01:55:14 am
content: http://www.harborfreight.com/automotive-motorcycle/horns/12-volt-super-loud-air-horn-40134.htmlNo idea if it would actually put out 135dB but it's likely plenty loud. The 10W rating is a typo - they probably meant 10A.Presumably, you could PWM it to start at maybe 80dB or so and ramp up to full volume in about 10 seconds, to make it slightly less of a surprise.

author: helius
author_rank: Super Contributor
timestamp: October 18, 2016, 02:49:23 am
content: Quote from: MK14 on October 17, 2016, 05:47:14 amThe robot bloodhound in "Fahrenheit 451" was armed with a hypodermic syringe.

author: SkyMaster
author_rank: Frequent Contributor
timestamp: October 18, 2016, 04:39:27 am
content: Back in December 1989, Radio Electronics magazine had an article about building a "Phasor Property Guard" that could "... protect your valuables by scaring criminals away with an unbearable ear-piercing sound."The article starts on page 37 -www.americanradiohistory.com/Archive-Radio-Electronics/80s/1989/Radio-Electronics-1989-12.pdf

author: MK14
author_rank: Super Contributor
timestamp: October 18, 2016, 04:59:00 am
content: Quote from: helius on October 18, 2016, 02:49:23 amOr better still get these guys, from Terminator. Don't be greedy, just buy 2 or 3 per room, and you should be fine:

author: GreyWoolfe
author_rank: Unknown
timestamp: October 18, 2016, 11:30:20 am
content: Years ago, I did a simple alarm using 2 110 dB sirens. Plenty loud enough to get everyone's attention. Now, my sirens weigh 40 and 70 lbs apiece with the added benefits of very sharp canine teeth and very protective attitudes.

author: Fungus
author_rank: Super Contributor
timestamp: October 18, 2016, 01:34:36 pm
content: Quote from: Ecklar on October 16, 2016, 11:52:37 pmThere's a reason for that.120db is plenty in an enclosed space. Use multiple sirens for larger spaces.Add strobe lights, a few confetti guns, a wind machine and a water sprayer for extra effect.What's the floor like? Could you squirt baby oil all over the floor? With enough baby oil and a strong wind machine it could take them several minutes to escape.Can you get stink bombs on eBay? I don't think I'd enjoy being sprayed with stink bomb liquid while I was being blown around a slippery room full of strobe lights and sirens.

author: CM800
author_rank: Frequent Contributor
timestamp: October 18, 2016, 04:05:33 pm
content: Quote from: Fungus on October 18, 2016, 01:34:36 pmStarting to sound more and more like home alone.Most building's ceilings have a load of slots running along them about 1ft wide or so between the beams, put flaps on the bottom (on your room's ceiling) and fill them with marbles. Have them drop ALL the marbles at once, fire off a mini air raid siren and 2 commerical smoke machines.

author: Zero999
author_rank: Super Contributor
timestamp: October 18, 2016, 05:29:32 pm
content: Quote from: Ecklar on October 16, 2016, 11:52:37 pmBecause as many people here have already said, it would be too big.I think you're unaware of the fact that dB (not db) is a logarithmic scale. Every 10dB increase in sound pressure is 10 times the power, so 20dB is 10 times as much power as 10dB and a 135dB siren would need to be 31.6 times the size of a 120dB siren, which is why it's impractical.

author: Fungus
author_rank: Super Contributor
timestamp: October 18, 2016, 05:35:24 pm
content: Quote from: CM800 on October 18, 2016, 04:05:33 pmBut nothing that would directly hurt them... just make them think very long and hard about coming back again.(and would make a very funny video)

author: SeanB
author_rank: Super Contributor
timestamp: October 18, 2016, 06:42:09 pm
content: Well here in south Africa there is a good selling burglar deterrent that works really well. A can ( or more than one) of pepper spray ( the regular type you use for personal protection, in a larger can) and a high wall mounted dispenser that fills the room when activated. Unless your burglars come with suitable protective clothing and a full mask and breather they will not like it, and will not be able to do much while their eyes are watering uncontrollably.

author: ez24
author_rank: Super Contributor
timestamp: October 18, 2016, 07:05:39 pm
content: Quote from: SeanB on October 18, 2016, 06:42:09 pmSounds interesting, I could not use it because I have deaf dogs. Can you provide a link?

author: Marco
author_rank: Super Contributor
timestamp: October 18, 2016, 07:06:08 pm
content: Inferno hasa thesisresearching hearing damage of their system on their website (link found onwikipedia's Sonic Weapon page).

author: ez24
author_rank: Super Contributor
timestamp: October 18, 2016, 07:08:55 pm
content: Quote from: Marco on October 18, 2016, 07:06:08 pmI tried to find this, thanks. Now if only someone would take one of these and make an alarm out of it. I wonder what the OP is up to?

author: nctnico
author_rank: Super Contributor
timestamp: October 18, 2016, 07:13:49 pm
content: Quote from: wilfred on October 17, 2016, 12:52:46 amI agree. The burglars won't mind (they probably wear ear plugs anyway) and the neighbours will be annoyed. I wouldn't be surprised if there are legal limits on the amount of noise an alarm may make and how long that noise is allowed to last.

author: bitslice
author_rank: Frequent Contributor
timestamp: October 18, 2016, 07:56:00 pm
content: Have you thought of playing an MP3 of "Ebony And Ivory", by Paul McCartneyI'd happily leave the planet to avoid hearing that turd again.

author: Ecklar
author_rank: Regular Contributor
timestamp: October 18, 2016, 08:02:11 pm
content: Quote from: NiHaoMike on October 18, 2016, 01:55:14 amYour idea is probably the most practical starting point.

author: MK14
author_rank: Super Contributor
timestamp: October 18, 2016, 08:07:54 pm
content: Quote from: bitslice on October 18, 2016, 07:56:00 pmThere's some modern stuff, which is much better.

author: MK14
author_rank: Super Contributor
timestamp: October 18, 2016, 08:14:27 pm
content: Quote from: Ecklar on October 18, 2016, 08:02:11 pmWhy can't you get professional/sensible advice on how to secure a home, against burglars ?If what you are planing had any merit. Then people would probably be using the method by now.So it scares them off once, they then return with ear defenders/plugs and clean you out.

author: nuno
author_rank: Frequent Contributor
timestamp: October 18, 2016, 08:17:17 pm
content: An array of those small cheap window reed/magnet alarms?

author: chickenHeadKnob
author_rank: Super Contributor
timestamp: October 19, 2016, 12:32:28 am
content: This is a solved problem, the original poster is just focused on the wrong sense modality. Commercial alarm system room foggers have been available for 20 or more years now.I don't know of any countermeasure short of disabling the system before it goes off.but what do I know with my beer talk.

author: Marco
author_rank: Super Contributor
timestamp: October 19, 2016, 12:53:46 am
content: Quote from: chickenHeadKnob on October 19, 2016, 12:32:28 amWon't that coat everything in the room in propylene glycol? (It doesn't readily evaporate.)

author: ez24
author_rank: Super Contributor
timestamp: October 19, 2016, 01:44:07 am
content: This is the way to gotrain horns - that is what you neednot cheap howeverhttp://www.ebay.com/itm/Die-Cast-Nathan-Airchime-K5LA-Train-Horn-Air-Horns-/281302781128?hash=item417ef3ccc8:g:-GkAAOxy0x1TPzc2&vxp=mtrQuoteI think a real train horn inside would shock someone

author: chickenHeadKnob
author_rank: Super Contributor
timestamp: October 19, 2016, 01:45:52 am
content: Quote from: Marco on October 19, 2016, 12:53:46 amI don't know but I suspect it will, however it is easy to wash off and non-toxic. You just need to wipe down all hard surfaces and hope you have slip-covers on your furniture. It can't be worse than years of exposure to nicotine tinged cigarette smoke. Some folks live in that filth their whole lives.

author: ez24
author_rank: Super Contributor
timestamp: October 19, 2016, 02:46:00 am
content: Here is the real dealhttps://www.hornblasters.com/products/details.php?i=nathan-airchime-k5-k5la-train-hornYou wanted an EXTREMELY LOUD siren

author: AlanR
author_rank: Regular Contributor
timestamp: October 19, 2016, 02:49:38 am
content: A huge array of ultra bright blue LED's are very effective at keeping thieves away. Just have to pulse them with the right frequency. Makes them feel sick to the stomach. Also, no noise to wake up the neighbors.

author: vodka
author_rank: Frequent Contributor
timestamp: October 19, 2016, 06:52:52 pm
content: That is the best that you have a danger pet on the home for protecting from burglars . That is as joke of the burglar and danger pet.A burglar go into in a house, he found that the home is full the advice of the danger pet("Careful", "Dangerous animal") . Until he arrived to room where he found a little cage inside it , there is a little parrot.So the burglar begin to mock the parrot until the parrot shout " Sultan, Attack" ,then a huge dog appears..Now reallly, apart of the alarm system , you have to have a pair the dogs (Style Spanish Mastin , Alano or other dog) on his garden.https://youtu.be/1kl7QpR7K5Ahttps://youtu.be/j5IKpQO9cp4