Ultrasonic Sensors

Where do you people come from? js

Constant false alarms

What you are proposing requires "dual photo-eyes". A type of infrared invisible beam detector. Around $300 for a good set, 1 set for each perimeter side. This is not a DIY project.

Belgium?

Should we tell him that he's already in the thousands of dollar range without seeing the job?

| > I need a device similar to what I see on upper-priced automobiles that | > indicate the presence of items around its perimeter. | > I have seen a very nice system mounted on the bumper of a BMW that | > works extremely well to indicate a person walking around the vehicle. | >

| > The sensor must be designed for outdoor/external applications. | >

| > There will be a series of sensors with patterns that overlap to provide | > detection around the entire perimeter. | > They will all be wired to a controller that will sound an alarm when | > the perimeter has been entered. | >

| > Perimeter size can vary from one hundred to several hundred feet. | >

| > Since they will be used outdoors, what will the issues be? | >

| > Therefore, I am looking for low-power, reliable sensors and the | > suggested controller to manage the system. | >

| > Of course, price will be a determinig factor. | | Where do you people come from? | js | >

| | |

I need something similar for my daughter. :-)

I think we just did. js

To keep her in or out? ;-) js

Keep guys away from her. :-)

True. Also, ultrasonic detectors don't have anywhere near the gentleman's requested range.

Outdoor photobeam detectors start around $135 for a 500 foot DS model. IntelliSense (Honeywell) makes a 250 foot, single beam, outdoor photoelectric that retails for $122.

Although not exactly what the gentleman asked for, Optex has an interesting photoelectric that s designed to mount on the outside wall of the home, providing protection for a row of windows. It retails for $125. There are numerous other reasonably priced options for outdoor protection.

That depends on the DIYer. Most people have no interest in installing their own security systems so for them it's not a DIY project. However, those with a modicum of tool skills and a bit of patience can DIY install a system. It's not rocket science. Photoelectric detectors consist of a transmitter and a receiver. The devices require (at a minimum) 2-conductor wire to the transmitter and 4-conductor wire to the receiver. Each needs to be mounted on a sturdy post, fence or wall. An alignment light is clipped to the transmitter, pointing in the direction of the receiver. The DIYer then adjusts the lens at the other end until a spot of light coming through the lens rests on the sensor. The alignment light is then moved to the receiver end and the identical procedure is followed to align the transmitter. This all takes a few minutes.

The hardest part of installing outdoor photoelectric motion detectors is running the wire. Most of the time it's run below ground. A tool called a "ditch witch" can cut an 18" deep by 2" wide trench for wire burial (be sure to use cable that is rated for direct burial and check with your building inspector for recommended depth of the trench to avoid damage due to ground frost in winter).

Good quality photobeams properly installed will remain aligned for several years unless they're impacted. When they need adjustment you take out the alignment light and repeat the procedure above. Periodic attention to insects and cleaning of the lenses will keep them running for many years. Speaking of insects, I like to douse a small piece of sponge material with Raid and leave it inside the detector, then seal all openings with caulk or RTV. That generally keeps even outdoor detectors bug free for years. Any time you service the unit squirt a little more Raid on the sponge. Be sure the sponge is not in direct contact with the lens or the circuit board.

I sell outdoor photobeam detectors as well as lots of other alarm, CCTV and automation systems online so I'm a bit biased in favor of DIY -- just as many of the posters who install this stuff for a living are biased against DIY. :^_

Teenagers tend to be much too resourceful to be stopped by an alarm system when there's a girl involved. :^)

Come back to planet earth.

Ultrasonic technology was used in the '80s with limited success. We are all using Passive infra-red, microwave, or a combination of both.

You need to contact a local dealer and see what is available in your area.

Not to mention underground telephone, cable lines, electric, sprinkler systems, electric and anything else that might be in the way, when an unexperienced person grabs ahold of a ditch witch. Can be a dangerous tool for the novice. Be Careful If You Choose To Use This Type Of Machinery. Call For Locates. There are companies that will do the locates for you. Then if you hit something they will be responsible.

Unless you hit an a/c svc line with a walk-behind trencher.... if so, your widow will be responsible for finding out who was responsible for locating the services. ;-)

I bet that would do wonders for the business end of the trencher too. Might knock off a tooth or two.

Yep. In another life, around 87-88, I did aerial and underground line construction for a Cencom cable contractor (Cencom eventually became Charter) One of our crews hit a 3-phase line with a large Ditch Witch 3500 rider, and it literally blew large rocks and pieces of dig chain out of the trench up to 75 ft. away. Luckily, the operator had the good sense to jump as far as he could off of the trencher onto the ground. Would have killed him for sure if he had stepped off of it. Didn't hurt the trencher at all- new chain and it was good to go.

The chain looked pretty gnarly when it came out of that trench. Operator was relegated to shovel duty for a long time afterward... "I didn't see that Locate...really."

After they unwelded it from the 3-phase?

They're called utilities, as in electric power, CATV and telephone companies. They don't charge for coming out to locate their wires for you. There's a page in the front of most phone books with the heading, "Call Before You Dig".

Found a lot of high power cables less than 36" below grade, have you? Power companies lay their lines deeper than the trencher can reach.

Here's an image of a Ditch Witch 3500:

Thought you had me on "ignore" Robert.

The utility companies do, phone and cable don't on their laterals. But then we always have the DIYer that gets tired of digging and burys romex, or if he is real cheap, that lamp cord, out to his new Home Depot light post. Or maybe he needed to add that extra circuit for his Christmas lights out in the middle of his yard. He hardly got more than 12-16" down. Never consider the obvious do ya! You just never know what the last guy did. I loved the DIYer that had a speed bump in his drive way. The PVC went right across with asphalt over the top. Of course he was proud that he got it over there with such ingenuity.