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A Field Guide to Office Technology

A Field Guide to Office Technology

by Ed Sobey

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With more than 160 entries detailing everything from the junk buried in desk drawers to that mysterious box blinking away in the coat closet, this practical guide navigates through modern office technology. Each entry includes a functional description of a device (what it is and how it works) as well as particulars on who invented it and how its design has evolved


With more than 160 entries detailing everything from the junk buried in desk drawers to that mysterious box blinking away in the coat closet, this practical guide navigates through modern office technology. Each entry includes a functional description of a device (what it is and how it works) as well as particulars on who invented it and how its design has evolved over the years. Devices are grouped according to their habitats—in the conference room, hanging from the ceiling, or connected to a computer—to assist in quick and easy identification. Solving office mysteries, such as why telephone keypads have their ones in the upper left corner while calculator keypads place the ones in the lower left corner, this fascinating resource decodes the often confusing technological landscapes of everyday offices.

Editorial Reviews

School Library Journal

Adult/High School In the same breezy, nontechnical language as his books on household technology and roadside technology, Sobey examines some 160 items in and around the average desk environment. Arranged by habitat (on the floor, on the walls, connected to a computer, behind-the-scenes), the entries explain the item's behavior, its location, and how it works. For many of the devices, he adds "unique characteristics" and/or "interesting facts." The author moves effortlessly and unapologetically from the simple to the complex and back again. The paper clip, pen, and pencil receive as much attention as the network server, GPS, and Split 50. Some items seem odd choices for inclusion. While readers might expect to find the proverbial watercooler, the flushless urinal is not always thought of as office technology. Teens will appreciate Sobey's sense of humor: in addition to binding papers and other materials together, another purpose of a rubber band is to fly across the office from the fingertip of a bored employee. Each entry has a small but serviceable black-and-white photo. A fun, informative survey.-Robert Saunderson, Berkeley Public Library, CA

From the Publisher

“Fun, informative, and easy to use.”  —School Library Journal on A Field Guide to Roadside Technology

A useful little guide to all those puzzling doodads you see when the family takes its annual road trip.”  —Atlanta Journal-Constitution on A Field Guide to Roadside Technology

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Read an Excerpt

A Field Guide to Office Technology

By Ed Sobey

Chicago Review Press Incorporated

Copyright © 2007 Ed Sobey
All rights reserved.
ISBN: 978-1-61374-176-4



A FEW YEARS AGO I was dropping off a proposal at Paul Allen's office. I knew it was unlikely that I would see him, but I was looking forward to seeing what the (outer) office of one of the world's richest men looked like.

I walked down the corridor and was 20 feet from his office door when a voice greeted me. The voice was from somewhere above or behind me; I couldn't tell where.

"Can I help you?" asked the faceless voice.

Not sure who was talking or who the voice was talking to, I continued toward the door. But then the voice repeated itself.

I looked around again and not seeing anyone, mumbled, "I have a package to drop off."

"Deliver it to room 200, down the hall and one floor down," directed the voice.

Not only was I prevented from seeing the great man, I couldn't even see his office or the person behind the mysterious voice. I couldn't get in the front door.

Just getting into an office today involves technology that didn't exist a few years ago. Of course some technology, such as keys and mechanical locks, has been around for centuries. But parking lot magnetic card readers and remote control door openers are fairly new. They provide a high level of security and certainly a dose of awe.

If you're able to get into the office, another layer of technology awaits you. An emergency enunciator mounted in a wall is ready to tell incoming fire and rescue workers where the trouble is. A time clock may be ready to tell your boss where you are ... or where you aren't. Security control boxes and keypads allow you to enter your office and punch in a code to keep the alarms from going off. Automatic door closers and exit lights help keep us safe.

So don't just walk into an office; play the sleuth. Take another look at the stuff in plain sight that you've seen hundreds of times before not knowing what it is or what it does. Then search this chapter to find the answers.

Garage Door Opener Touch Pad


Allows you to open a parking gate or garage door without a handheld remote control unit kept in your car. System managers can change the code to keep out people who no longer warrant access.


Touch pads are mounted on metal poles or stands immediately in front of the gate, so you and only you can drive in when the gate opens. The same type of device is used outside office doors to keep people out of restricted areas.


When you punch in your code, it is recognized by a logic circuit in the garage door electronics and opens the door. The motor that opens the door is started by the adjacent circuit. Typically the door or gate closes after a fixed time period.

For vertical doors, the motor doesn't lift the entire weight of the door, which can be enormous. Springs counterbalance the door's weight, so the motor does less work. In sliding gates, the weight is supported by wheels that run on rails or on the ground.


Some systems allow managers to record entry into the garage or lot, so they can tell who is on the premises at any time.

Parking Lot Sensor


Opens the gate or door so you can leave the garage or lot.


The sensor is installed in the ground in front of the exit lift gate or door, or installed two car lengths in front of the gate.


Some garages require you to use the same remote control to leave that you used to enter. However, most employ some type of sensor to detect the presence of a car or motorcycle (but probably not a bicycle — you're out of luck unless the garage provides a manual push button).

One approach to opening the gate is to bury a coil of wire in the ground and run an electric current through the coil. The coil generates an electromagnetic field. When a car drives on top of the coil, it changes the magnetic field and the change is detected by a sensor. The exit door or gate system continuously checks the sensor to see if the field has been changed. When the sensor "sees" the car (a changed magnetic field), the system starts the motors that raise or move the gate.

Some systems use an infrared beam to detect cars. You can see the beam transmitter off to the side of the gate or door. It has an eye-like device that allows infrared radiation to pass. It may have a second eyelike glass cover where the beam, reflected from a silvered device on the opposite side of the driveway, bounces back to it. This two-eyed system is less expensive because it doesn't require installation of a sensor on the other side of the driveway.

In the alternative system, the detector is located on the other side of the driveway. Cars waiting to leave block the beam to trigger the gate to open.


In-ground cables for the sensor are usually installed after the lot has been paved. So look for a black square or circle in the ground where the sensing cable was installed and covered with hot tar.

Security System Keypad


Allows workers to enter the office without setting off the alarms. Workers enter a code to arm (when leaving) and disarm (when entering) the office.


The keypad is located inside the entry door used by staff. It is inside to protect it from tampering. Being inside requires that it have a programmed delay — about 30 to 45 seconds — so workers can enter and disarm the system by punching in a code before it triggers an alarm.


The 12-button keypad contains switches that are activated by pushing. When you push a button, it closes a switch and signals the system microprocessor. When the programmed code is entered, the microprocessor activates or deactivates the alarm system.

Each individual can have his or her own code so the system can identify who set or disarmed the alarm.


You might have noticed that keypads and calculators arrange the numbers in different sequences: calculators have the "1" in the lower left, while keypads have "1" in the upper left. Calculators replaced mechanical adding machines and followed their arrangement of numbers. Keypads were developed by Bell Labs to replace the rotary dial telephone. If Bell Labs had followed the calculator key placement, the alphabet would start in the lower part of the pad and end with "WXY" in the top row, so it opted instead to present the alphabet in order from top to bottom and left to right.

Front Door Lock


Keeps out (some of) the people you don't want inside, but gives those you do want inside easy access.


Mounted on the side of the door opposite the hinges. Located at a convenient height to allow users to insert a key to open the door.


Most doors use a cylinder lock. Inserting the correct key allows you to rotate the cylinder, which is connected to an arm that withdraws the latch keeping the door secure. The latch is usually pushed closed with an internal spring after the key is removed.

The beauty of the lock is that each has its own code that protects it. The code is cut into a metal key. The vertical indentations in the key correspond to both the placement and heights of pins inside the lock. As the key enters, it pushes the spring-mounted pins up and out of the way. A key with a different code will not push the pins to the correct heights that allow the cylinder to turn.

From inside you can operate locks by turning a knob or using a key.


The first lock system that used keys was created in Sparta around 400 B.C.



Gains access to locked doors and devices.


Keys hang around key chains or amidst lint in pockets. For a device whose only function is to open locks, they spend remarkably little time in locks.


Mechanical locks use keys that push internal pins out of the way. When all of the lock's pins are compressed by ridges on the key, the tumbler can turn, unlocking the lock.


In the photo the key on the left is a tubular key. The center key is a traditional key, and the key on the right is a high-security key blank made by ASSA.


There are many varieties of keys and locks. Here are some of the common types.

Tubular or axial pin tumbler locks and keys are used occasionally on office doors, but more often on vending machines and bicycle locks.

Cylinder locks rotate to open, after the key has been inserted. These are the most common door locks.

• ASSA and other high-security keys have unique shapes (the blanks are sold only to authorized dealers) that make it difficult to make unauthorized copies.

Magnetic Card Reader


Allows entry to an office without a mechanical key. The magnetic card identifies who is entering so a record can be kept. In this world of downsizing companies, it is easy to reprogram the system to deny access to those who are left out in the cold.


Card readers are mounted on the walls outside the office doors or outside gates protecting garages and parking lots.


The plastic card has a film of magnetic material, like magnetic tape from a cassette tape recorder. The tape is plastic film embedded with tiny iron oxide particles that act like magnets. Electromagnetic encoders align the tiny magnets on the card so a read head can read them. If exposed to strong magnetic fields, the particles can be remagnetized into a new pattern, thus losing the code. In that case, you can't get in! Some systems also have a keypad for calling someone inside to open the gate or to punch in a code to gain entry.

In addition to magnetic card readers, security systems can use optically encoded cards (bar codes) or radio frequency identification (RFID) technology. RFID can be active (requiring a battery) or passive (using the energy of the incoming radio signal from the lock system) to power the onboard electronics circuits. Active RFID sends out a radio signal (up to 300 feet) identifying the owner so the receiver will open the gate. Passive systems are useable for a much shorter range.

Door Alarm


When the alarm system is operating, it detects an opening door and sounds an entry alarm.


These devices are visually innocuous, and you may miss them. Look along the inside, upper edge of doors that open to outside the office. If you see a small device mounted to the door, look for a corresponding device mounted on the door frame. The device on the door frame will have a wire trailing out of it and running along the door frame.


The device mounted on the door is a magnet. Its corresponding piece on the door frame is a reed switch. The presence of the magnet pulls together two metal contacts inside the switch so current can flow through the system. This configuration is called "normally closed." When the door is open with the alarm system engaged, the system senses that the circuit is no longer complete and it signals an alarm. "Normally open" reed switches also can be used, in which case opening the door closes the circuit to signal the alarm. The wire running along the door frame connects the reed switch to the alarm system.


You can sometimes find the same system on windows that slide open and shut.


The reed switch is one of the many inventions of the old Bell Telephone Laboratories.

Security Panel or Alarm Control Box


Controls the perimeter alarm system and may also control other alarms — motion, fire, and smoke detectors — throughout the office.


It is often located near the entry door or in a nearby closet, mounted on the wall. Typically, it is a gray-colored metal or white plastic box, but it can be painted to match the walls. In companies that have security guards, the alarms are located in or near the guard station.


A microprocessor inside the device receives the codes entered via a keypad by arriving or departing employees. On leaving at the end of the day, the last worker out enters a code to start monitoring alarms for entry. Once the correct code has been entered, the microprocessor waits a set period to allow the worker to leave and lock the door before activating the alarms.

The first employee entering at the start of the day will trigger perimeter and motion detector alarms, but the system will wait to sound the alarm, giving the employee time to disarm by entering the code.

System managers can set and change the code in the microprocessor. Every few months they should change the code, hopefully getting copies to all the employees who need it.

Some systems also monitor the fire and smoke detectors, or monitor sound levels inside the office. When any of these alarms is triggered, the system can send a message by telephone lines to a remote security company, or a police or fire department.

Entry Alert Device


People entering an office interrupt a beam of infrared light, and the device sounds a chime or tone to notify employees of their presence.


These are mounted a few inches above the floor on both sides of the entry door.


The system uses a microprocessor that sends a tone or chime to speakers whenever the beam of infrared light is interrupted. One device mounted on or near the doorway near the floor generates an infrared beam of light. A second device detects this beam. The second device is mounted on the opposite side of the entryway. Alternatively, both the light transmitter and receiver can be mounted one above the other, in one box. In this case a reflector (like a reflector mounted on a bicycle) is mounted on the opposite side of the doorway. The infrared beam crosses the doorway and reflects back to the receiver. When someone interrupts the beam, the circuit detects his or her presence and sends the tone to the speakers.

The microprocessor continuously looks to determine if the detector is "seeing" the beam. It queries the detector many times each second, so even a short interruption in the beam will be enough to trigger the tone.


Look for the beam transmitter and receiver. Mounted in the same unit, they appear to be two eyes, one above the other. Look for the small reflector on the other side. If you missed seeing them when you walked in, your first clue to their presence will be the chime announcing your arrival.

Emergency Enunciator


Announces emergencies and helps locate them for responding emergency crews. Imagine the fire department showing up at a huge building and not knowing where the fire is. This device shows where the alarms have been triggered.


Emergency enunciators are located in the entryway or security stations of office buildings.


When sensors and alarms in a building are activated, their location is indicated on the enunciator. Some systems also report mechanical problems with machinery in the building. In medical facilities, enunciators are used to alert on-duty staff to call buttons or wireless emergency buttons (panic buttons). Emergency responders can check the enunciator to find where the problem is.


In any large building, look near the lobby, elevators, or front doors for a panel that lists locations throughout the building.

Door Closer


Closes an office door without having it slam.


Door closers are located on the upper inside surface of most doors.


The closer is attached to both the door and the door frame. Opening the door extends the mechanical arm, which turns a mechanism inside the drum attached to the door frame. Releasing the door allows the closer to pull the door closed, resisted by a hydraulic piston.

Opening the door stretches a spring inside the mechanism. The spring, strong enough that you don't want to open the mechanism to look at it or attempt a repair, pulls the door shut. A piston filled with hydraulic fluid resists that motion, slowing the movement of the door. Struts or shocks and springs in your car work the same way.

You can adjust how fast the door closes with one or two small screws on the mechanism, but removing the screws may allow the hydraulic fluid to leak out.


Lewis C. Norton invented the first door closer in 1877.

Electromagnetic Door Release


Releases fireproof doors in the case of fires to prevent their spread.


Excerpted from A Field Guide to Office Technology by Ed Sobey. Copyright © 2007 Ed Sobey. Excerpted by permission of Chicago Review Press Incorporated.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.

Meet the Author

Ed Sobey is the director of the Northwest Invention Center and the author of several hands-on science books, including A Field Guide to Household Technology, A Field Guide to Roadside Technology, Inventing Toys, and Loco-Motion.

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