Portable Door Alarm Can Keep Intruders Away : Other products include a soothing sound machine, an emergency data card and an anti-bacterial toothbrush.

Recently, a New York television crew showed on hidden camera how easily intruders could get access to guest keys and guest rooms in some of the city’s top hotels--and other investigative stories have revealed similar problems in hotels around the world. The situation, which could be life-threatening if the guest is unfortunate enough to be in at the time, has prompted countermeasures.

For example, Telko, which manufactures a wide range of business and home security devices, has developed a portable door alarm that sends out piercing alarm beeps or loud chime sounds if the door is jarred or the knob turned.

The vibration-sensing alarm hangs over the inside door knob and can be set to either chime or alarm. A dial adjusts the alarm-activation time to between five and 15 seconds of being jostled. The alarm operates on one 9-volt battery (not included), and there’s a tiny red light that glows if the battery is low. The alarm comes with two red-and-white warning stickers stating that the “premises are protected by electronic surveillance.”

I tried the alarm on my apartment door. It worked so well that my next-door neighbor came rushing over to find out if I was in trouble. The long beeping alarm is far more piercing than the three-note chime sound--and thus, in my opinion, more effective. The timing device on my alarm was ineffectual. No matter how I set the dial, from five to 15 seconds, the alarm went off as soon as the doorknob was turned. The defect didn’t seem to make the alarm less effective, just more trigger-happy.

While gentle knocking on the door (as a hotel maid or room-service waiter might do) will not trip the alarm, hotel personnel who abruptly enter the room while the alarm is set will no doubt get quite a scare. Any traveler who has had the misfortune of being walked in on at an inopportune moment by a housekeeper or waiter who has neglected to knock first (a serious breach of hotel protocol), no doubt will relish this opportunity for both forewarning and revenge.

Home Security Vibration Door Alarm/Chime (334175), $14.95 from The Safety Zone, (800) 879-7070. A similar model offers a choice between a piercing alarm and dog barks (in lieu of chimes). The Safety Zone sells this version, (334144), for $19.95. No matter how sincerely you ask for a quiet hotel room, there’s no guarantee that outside sounds won’t intrude. Airplane noise, loud neighbors, comings and goings in the hallway, and the beeps and screeches of road traffic can conspire to make a good night’s sleep maddeningly elusive. The Marsona Portable Environmental Sound Machine takes a queue from “white sound” devices New Yorkers have been using for years to mask the sounds of the city. Just plug in the machine (dual-voltage adapter is included), select the environmental sound you prefer (“rainfall” or “waterfall” or a mixture of the two) and adjust the volume to suit.

The machine worked fine for me but is unlikely to calm light sleepers who are kept awake by all sound, water sounds included. Also, really loud neighbors and external noise will break right through the sweet pitter-patter background. Still, for blocking low-level noise intrusions, I found the Sound Machine comforting indeed.

Marsona Portable Environmental Sound Machine (30709M), $119.95 from Hammacher-Schlemmer, (800) 543-3366. A domestic-voltage model for 110-voltage outlets only (30708M) is $99.95. In traffic accidents or other health emergencies, speedy treatment often is of the essence. But if the patient is in shock or unconscious (or simply doesn’t remember key information such as blood type or allergies to medications), getting timely treatment can be jeopardized.

HealthShield Resource Data, an Ohio company, manufactures a credit-card-size Emergency Medical Data Card that goes far beyond the bare-bones information provided on medical alert tags and bracelets. The process works like this: You fill out a legal-size form with an extensive amount of information, including allergies to foods or medications, hospitalization history, health insurance details, names and phone numbers of religious counselors and emergency contacts, even emergency surgery and organ-donor authorizations. (You can leave any questions you find intrusive blank.)

You mail the form to HealthShield, which has the document reproduced on microfilm measuring 1 1/4 inches by 1 inch. The microfilm is laminated onto an ID card, which is labeled “Healthshield Emergency Medical Data” in bright blue and red letters. The back of the card contains the instructions that the information can be read with the help of a magnifying glass, microscope or microfiche reader. The ID contains a warning that medical information may have changed since the card’s issuance. Of course, much depends on the card being found in a timely fashion and on hospital personnel’s willingness to take the time and effort to decipher it. Even so, as they say, it couldn’t hurt.

To get a brochure and application form for the HealthShield Emergency Data Card, write to HealthShield Resource Data, 8166 Montgomery Road, Suite 437, Cincinnati, Ohio 45236. The completed application should be returned to the company with a check for $19.95. Victorinox, maker of the Swiss Army Knife, has developed a compact emergency kit that is both swank and useful. Packed into a 4-by-4-by-1 1/2-inch black leather pouch with velcro-fastening flaps and belt slits are some 19 items that can solve travel crises ranging from losing a button to getting lost in the wilderness. To start, there’s a Swiss Army Knife with 31 tools, including two blades, five screwdrivers, scissors, a chisel, pliers, wire cutters and a tiny ballpoint pen. The other items, all in miniature versions, include whetstone, compass, thermometer, flashlight, whistle, matches, adhesive bandages, sewing kit, mechanical pencil, note paper, safety pins, comb, ruler, fishing line, two toothpicks, tweezers and signal mirror.

For people who love gadgets this is a nifty package, and I couldn’t resist opening all the knife tools and playing with the other items, especially the tiny compass and flashlight. Certainly no one needs to spend such big bucks for a little sheet of graph paper, doll-size comb, book of matches and minimal sewing kit. But the knife is top quality, and the way everything is packaged together makes this a snazzy gift for the Ralph Lauren set.

The Victorinox Swiss Army S.O.S. Kit, $135, is available from Travel-Smith, a mail-order firm based in San Rafael, (800) 950-1600. Compact Designs, a New York company, claims its anti-bacterial Hygeia toothbrush is made of bristles that neutralize the germs that can build up in normal toothbrushes. According to the company, most toothbrushes breed bacteria in the holes holding the bristles because of the moisture that remains after brushing. With the Hygeia toothbrush, an anti-bacterial ceramic crystal is molded into the bristle base, supposedly allowing the toothbrush to self-sanitize.

A number of dentists I consulted said that the amount of bacteria harbored in normal toothbrushes was harmless for most individuals if the brush was well-rinsed after using. As for the Hygeia brush, they said it might help, and it certainly wouldn’t hurt.

I liked the Hygeia brush for an entirely different reason. It makes a great travel toothbrush. It has a round, easy grip handle and a nifty plastic cap that snaps over the brush end and is less cumbersome than other toothbrush holders on the market. And like the dentists say, it can’t hurt.

The Hygeia toothbrush, $5.95, comes in red , blue or yellow and is available through Compact Designs, (800) 289-8896.