Someone was in my shop Friday night

MossRoad · Dec 16, 2009

You need a car battery, a car horn, a relay that operates on 12V, a magnetic switch for the door(it will have Normally Open and Normally Closed contacts inside), some wire large enough to handle the horn current, some smaller wire, a couple small battery clamps and an on-off keyed switch for outdoor use.

Mount the horn above the door, under the eves pointing straight down at the door. Run the heavy current wire into the building.

Run a high current wire from the positive battery terminal clamp to the A side of the high current relay.
Run a high current wire from the B side of the high current relay to the positive horn lead.
Run a high current wire from the negative(ground) of the horn back to the negative battery terminal clamp.
The horn is wired. Now you need to wire the coil of the relay.
Mount the magnetic switch on the inside door frame.
Mount the key switch through the wall.
Run a small wire from the positive battery terminal clamp to the A side of the key switch.
Run a small wire from the B side of the key switch to the A side of the normally open contact on the magnetic switch.
Run a small wire from the B side of the normally open contact to the A side of the coil on the relay.
Run a small wire from the B side of the coil on the relay to the negative battery terminal clamp.

Clamp the clamps on the battery. Arm the switch. If someone opens the door, the horn goes off. Chances are they will leave the door open and run, which will leave the horn on until the door is closed or you turn off the switch. Pretty simple, but the horn will stop if the door is closed. So you may want to make a latching circuit that will keep the horn sounding even if they close the door. The only way to silence the horn will be to turn off the switch, or remove the battery clamps. I will have to find my circuit for that. There are a few ways to accomplish it. One is to use two relays. The first one triggers and holds the second one on. The other way is to use an SCR (silicon controlled rectifier). It is a simple circuit that is easy to build. I built many of them for our company security system. If someone opened a door it would latch an alarm on and the watchman would have to go to the door and turn a key switch to silence it, forcing him to observe the situation in person. I will try to find it.

Redbug · Dec 16, 2009

No offense taken at all, Dan. I guess I am out of sync with the rest of the world. And it's a refreshing eye opener.

The gate into my place is always closed, unless a friend has called or there is a delivery. So, no one wanders in and there's no excuse. It's a secure feeling. (However, I don't want to be lulled into a false sense of security, I know).

Anyways, back to Deere755. I think someone was casing his place and got scared off by the dog. The deputy said the crook may be back according to the first post in this thread. I think the deputy is right. Most folks said to keep things locked up and put up a camera and wire a horn system. I think you should also keep your gate locked...if you have one. And it may be worth the money to get one of those gate openers where you have a clicker and don't have to get out of the vehicle every time. Then it's easier to keep the gate shut all the time. You should expect them to come back and plan accordingly. And even if they don't come back, you will be in a much better position in the future. And I agree...death to anyone who kills my dogs...

eepete · Dec 16, 2009

MossRoad's wiring description was right on. I would suggest a fuse right off of the battery. They make in-line fuse holders for the automotive type fuses. Horn is probably less than 10 amps, that lets you use #16 wire for the high current stuff. That way if there is some problem with the small wire going to the magnetic door reed switch the wire won't be the melting fuse. If you're really paranoid, put a 2nd 2 or 3 amp fuse in just for the relay coil and door switch, then you can use 20 gauge wire for that.

The reed switches used for security stuff get real unhappy and have shorter life spans if you pass more that 100 mA through them. Horn relays are on the order of 40 to 60 mA. Ideally, reed switches want to see just a few milliamps and a purely resistive load, but in this application (where you will turn it off before you go in) is something that will hopefully on fire a few times a year (or less!). Between the higher contact current and the inductive kick when the relay coil is de-energized, the life could be only a few thousand cycles- again, enough for this application.
By contrast, for my security stuff I run one half of a milliamp through them, and should get on the order of half million to a million cycles out of them.

Pete

forgeblast · Dec 17, 2009

- Harbor Freight Tools - Quality Tools at the Lowest Prices

I am pretty sure its this one, i though it said it was a 30 amp. Ill check when i get home.

ok the info says 12 volts dc 110 db, and to install a 30 a fuse before use, i would also need a relay. according to the wiring diagram.

I was wondering if any of these would work?
https://www.surpluscenter.com/item.asp?UID=2009121717321170&item=11-3231&catname=
https://www.surpluscenter.com/item.asp?UID=2009121717321170&item=29-C-043&catname=electric
https://www.surpluscenter.com/pages/156.pdf 11-3146-A item number as the key off/on

eepete · Dec 17, 2009

Pet Peeve of mine: specifications for things that are silly. "old fashion sound", "high impact trumpet", and "100 dB blast". Useful specs would be voltage and current requirements, dimensions, mounting template.
And how 'bout for tractors we get a good old fashion torque vs. RPM curve?

Pete

Ronbo · Dec 17, 2009

Texas.
After dark law.
Enough said.

Ron

MossRoad · Dec 19, 2009

forgeblast said:
- Harbor Freight Tools - Quality Tools at the Lowest Prices

I am pretty sure its this one, i though it said it was a 30 amp. Ill check when i get home.

ok the info says 12 volts dc 110 db, and to install a 30 a fuse before use, i would also need a relay. according to the wiring diagram.

I was wondering if any of these would work?
https://www.surpluscenter.com/item.asp?UID=2009121717321170&item=11-3231&catname=
https://www.surpluscenter.com/item.asp?UID=2009121717321170&item=29-C-043&catname=electric
https://www.surpluscenter.com/pages/156.pdf 11-3146-A item number as the key off/on

I would just go to an automotive junkyard for a car horn( actually, I would go to my back yard where there is a nice rotting chevy truck!

) and get a used horn. And you may want to check out Radio Shack for the magnetic door switches, key switch and alarm wire for the low current stuff. For the higher current wire for the horn, go to an auto parts store and as suggested above, put an in-line fuse in the positive lead right off the battery just in case.

Finally, for the battery, get one that is the same size or a little smaller than the one in your car and get a battery tender. The battery tender will keep it fresh and charged and if the battery in you car barfs, you have a hot spare sitting there. Better yet, replace the battery in your car and use the original for the alarm. It will still function as a hot spare for your car.

deere755 · Dec 19, 2009

UPDATE They, Him or whoever was back exactly one week from the first time. I had a long week so I was sound asleep last night. I noticed this morning that someone had tried to pry the door open. My neighbor stopped by this morning to let me know that they spotted a car in my drive way last night at 11:07 almost the exact same time as last Friday. I called the Sheriff and a deputy came out. I know him but I was not impressed with him. I told him my neighbors had a decription of the car but he didn't seem interested. He said they would step up patrols in the area and I should put up some no tresspassing signs. I am sure that will keep them out. I think I will make a point of talking to the first deputy that I talked to. I was alot more impressed with him.

charlz · Dec 19, 2009

Along with the horn rig up a small LED light right where you would be looking when you open the door .... have it come on about 1 second before a bank of flash bulbs.... they should be easy pickin' while stumbling around in your yard

DennisArrow · Dec 20, 2009

YOU really have only yourself to fault for NOT stopping this. A neighbor is poor self-defense. Yes, they will hide behind a window in a dark room and report to you later. Seldom will they even call 911, let alone get out there and block the road or entrance. Much to much to even think about.

You had a week and a lot of advice as to what to do. Doing nothing and expecting others to do it for you is NOT going to protect YOU..........I realize this may seem harsh, and sorry if it comes across that way..........Quit complaining, reporting, or procrastinating and DO SOMETHING positive. YOU are the only self-protection that YOU have.......God bless........Dennis