Electronic Design

Where There's Smoke, There's Fire? Not Necessarily...

During a recent visit to my daughter’s new home, I witnessed a funny spectacle. While she was cooking breakfast and I was in the living room, the smoke alarms went off. My daughter ran out of the kitchen and charged up the stairs to the second floor.

As I watched her bound up the steps, I wondered what she was getting and whether or not she would beat the fire department, which might hear the shrieking alarms as far away as the fire house. Finally, she came rushing down the stairs with a portable fan clutched under her arm. Within a few moments she had cleared away enough smoke to still the alarms. The problem: she had burnt a couple of pieces of toast in the toaster oven.

What a joke, I thought. Smoke alarms are such an important safety feature in any home, yet home owners have very little control over them. When a so-called nuisance alarm occurs in my own home, I usually get on a chair, take off the alarm cover, and disengage the battery. I figure this is my punishment for buying an alarm for $9.99. After seeing how my daughter handled the problem, I decided to find out more about the state of the art in smoke alarms. I was sure I could find one with a remote control or at least a remote switch.


If you search for smoke alarms on Google, you’ll find out that you can buy wired alarms, wireless alarms, and battery-operated alarms. Wired and wireless alarms are easily networked together. So when one alarm goes off, they all go off, which is what happened at my daughter’s house.

I was most interested in the units that tout their ability to deal with nuisance alarms. A nuisance alarm is usually triggered from smoke emanating from the kitchen. Most alarms that are equipped to handle these situations have a switch on their cover.

The problem is that you usually have to climb on a chair or stool to get to the switch. This can be dangerous for older folks who might fall off the chair and cause an even bigger problem for themselves.

One enterprising smoke alarm company has come up with a novel way to solve the problem of reaching the nuisance switch. You can find the solution at SmokeSign.com. To help people avoid standing on a chair or stepstool, this company has developed a pull-down smoke alarm.

You just pull on a ring, and the alarm comes down the wall. With the alarm in front of you, you can push its button to silence it (if you’re not using your hands to cover your ears). After silencing the alarm, you pull the ring again, and the alarm goes back up the wall. It’s clever, but not too high-tech.

The next thing I noticed about smoke alarms is the use of two different types of sensors—ionization sensors, which are more common, and photoelectric sensors, which are supposed to be less prone to nuisance alarms. That’s a start, but how about a simple remote control or switch to deal with nuisance alarms?

I finally found a model from First Alert (www.firstalert.com). Rather than packaging a simple remote control with this product, which is probably a decision based on cost, the company built a receiver into the alarm that works with a universal remote. Smart thinking. This model, called the First Alert Dual-Sensor Smoke Detector w/ Point & Click sells for $39.99 at Radio Shack. This particular model does not appear to have the company’s Onelink feature, so you can’t link multiple units together.

I think a good solution would be to include one of those new wireless switches that harvest energy from switch presses, like the kind demonstrated by GreenPeak (www.greenpeak.com) at the 2009 International CES. The switch could be conveniently mounted in any location as long as it is within range of the receiver in the smoke alarm. This is a simple fix, but then again, it might add too much cost.


In other news related to fire alarms, the Signalink Technologies (www.signalink.com) Fire-Link II is a UL-listed powerline-networked system that activates audible and visible alarms inside apartments in buildings that do not have in-suite alarms.

When the main fire alarm system is activated, a loud audible alarm and a bright LED visual warning light (strobe) are simultaneously activated on the in-suite Fire-Link alarm device.

At the core of the Fire-Link technology is a communications platform and engine that is deployed across the electrical wiring infrastructure, which exists in any building as a ready-made network. This eliminates the need for additional wiring usually required when retrofitting apartments and condominiums.

By installing a single panel, Signalink’s technology can send signals via the existing electrical wiring in older buildings. Fire-Link connects with a building’s existing fire-alarm system and brings alarm devices inside apartments where previously there were none. The In-Suite Device (ISD) is the individual alarm unit. It can be plugged directly into any electrical outlet and firmly affixed to avoid accidental or intentional removal by occupants.

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