Advanced electronic circuitry and computer chips are present in every aspect of our lives these days, so it's no surprise to find them in a growing variety of power tools. While the old-timers still do their jobs well, tools with "smart" features offer enhanced performance, and, in some cases, safer operation. Here's a look at some of the new "smart" tools you'll find out there -- and how they work.

First, a definition. We call a power tool "smart" if it can electronically "sense" its environment and act or react to it. Toolmakers often cite an automobile's cruise control as an example of a smart feature: It moves the car 55 mph on even ground, but when the engine needs more power to maintain 55 mph on an incline, the gas pedal moves away from the bottom of your foot. In different ways, toolmakers are applying similar principles. The resulting new features can benefit tool users and tool-makers.

Brain Power

Complex yet affordable, electronic circuitry and computer chips are the components manufacturers use to give their products reactive functions. Circuit boards and chips generally monitor one of five things: speed, electric current draw, time, battery conditions, or electrical conductivity. Manufacturers are installing this technology in drills, routers, polishers, table saws, rotary hammers, hammerdrills, pneumatics, cordless tools, and even generators.

Speed Sensors. Blade or bit speed is where the action is on most power tools, so you'll find various forms of speed-sensing technology called electronic feedback control (EFC) on more tools than any other kind of smart technology. Generally speaking, this circuitry maintains constant blade or bit speed up to the tool's maximum output as cutting or drilling conditions change.

Tools without EFCs generally work like this: Turn them on and they instantly achieve maximum speed. Rpms drop and amperage draw rises when the tools are loaded, so the user must find a balance between physical pressure and amperage draw. Toolmakers say this is hard on tools and diminishes efficiency.

New EFC-controlled tools operate at optimum rpms or bpms and adjust power as needed when they sense resistance or overload pressure from materials or tool operators. And EFCs can disengage a tool if the speed jumps too rapidly.

A note of caution, though: As with any other electronic technology, the quality of EFCs varies. Lower-quality EFCs have a much wider margin of error when sensing and adjusting for different loads than do high-quality EFCs. Toolmakers say price and careful attention to product literature can help indicate circuitry quality. The application of these features is broad throughout the industry, but here's a glimpse at the kinds of tools speed sensors are hiding in:

• Makita calls its EFC system Speed Control. It is found in several of its routers and its LS1212 12-inch sliding miter saw. Makita is among the first to put EFCs into cordless tools; the company's three new battery-powered jigsaws have them. Not only do rpms remain constant as loads change, but EFCs usually produce soft-starts, too.
• Bosch calls its model 4000 table saw's EFC technology the Torque Response System. Torque Response soft-starts the saw, then runs it near 3,500 rpm. And, like a car's cruise control, EFCs keep the blade revolving at that speed even under serious load. EFCs are also at work on a number of Bosch rotary hammers.
• Metabo uses EFCs on a wide range of hammers, hammerdrills, and grinders.
• Milwaukee employs EFCs on several rotary and chipping hammers.
• Panasonic's EFC-controlled drill/drivers, hammerdrills, and rotary hammers are all cordless.
• Porter-Cable dubs its EFC technology Speedmatic. It's found on routers, random orbit sanders, siding shears, several drivers, a portable band saw, and a corded jigsaw.
• DeWalt puts EFCs on its routers and polishers. The company also puts them on corded drills, where they do something a little different. When a drill bit breaks through a piece of work, the bit's rpm typically jumps, causing the drill to twist out of the user's hand. DeWalt's Breakthrough Technology senses that rpm spike and pulses power to the motor. It acts as an electronic clutch, making it easier to hold the tool once the hole is drilled.
• Roto-Zip uses a microprocessor to control speed in its model REV01 Revolution spiral saw. Like EFC circuitry, the device monitors bit speed and senses load, then juices the tool as needed.

These electronic benefits might be hard to notice without a hard-read of the owner's manual, but tool manufacturers say they extend tool life and make their products perform better. A router or miter saw doesn't jerk in the user's hand as it's engaged, and gearing wear is diminished because the tool is not instantly pushed to full speed when activated as it passes through the work. And maintaining constant blade or bit speed enables some of these tools to run more quietly than their instant-on counterparts. Because their rpms don't change as conditions -- including material difficulties or user fatigue -- do, toolmakers say this yields greater efficiency and productivity.

Computer Chips: Pneumatics. Smart technology for nailers focuses on safety. There are several mechanical safety devices out there like on-off switches, evers, and fire-sequence scenarios, but Senco is the first manufacturer to equip a nailer with computer chips. The company's Frame Pro nailer with ThinkTrac technology features a microprocessor that senses the kind of nailing a user desires (bump or sequential) and temporarily disables the tool when idle.

The system combines a mechanical pre-set scenario with a tiny stopwatch: Depressing the nose to the work before pulling the trigger readies the chip for single fire. The chip then allows the user two seconds to dispense a single fastener. Depressing the trigger first readies the chip for bump fire. The user must then dispense a fastener every second or the tool will temporarily time itself out. The temporary time-out is easy to reset by depressing the nose or pulling the trigger. Doing so tells the chip which firing mode to use.

Computer Chips: Cordless. Cordless tools store brain power in their chargers. Batteries are like soldiers in the field. The best chargers are the equivalent of a supply depot and a MASH unit rolled into one. Chargers decipher what depleted batteries need to regain full voltage. They measure volts and temperature in the used batteries and then charge them back to full voltage. Once a charger senses a battery is slightly overcharged, it turns off. Unfortunately, this system generates unnecessary heat that can hurt batteries.

Tech Talk: The Language of Smart Tools

Electronic Feedback Control. EFC is a generic name applied to electronics embedded in many tools that detect information during tool use. They "react" to this information in a way that enhances tool performance, such as adding more power while keeping blade or bit speed constant under increasing load. Soft-Start. EFCs often carry soft-start functions in their circuit boards. This allows the motor to build speed slowly, instead of instantly hitting maximum rpm. Soft-start capability eases strain on tool gearing and makes for smoother tool operation. Speed Control. This is Makita's name for its EFC circuitry, which is found on some of the company's routers, a sliding miter saw, and some cordless jigsaws. In each case, the technology monitors blade or bit speed and adds power as necessary to keep it constant under load. Torque Response System. This is Bosch's name for the EFCs embedded in its model 4000 table saw. These electronics keep blade speed constant as load changes, providing more power as needed. Bosch 1-1/8- to 2-inch rotary hammers are equipped with similar circuitry. Electronic Variable Speed Control. This isn't an EFC. It is a trigger or a dial that changes blade or bit speed manually, not automatically like EFCs. Don't be confused. If you're buying a new router or jigsaw and you want EFC, make sure you're buying electronics and not a switch or trigger that you control.

Makita may have the most advanced system out there. Its new 24-volt system equips chargers and batteries with computer chips. Once a charger refuels a battery, it stores that battery's fingerprint in a chip. Battery packs are made up of individual, non-identical cells that drain at different rates. Makita says that reading and designing charging cycles yields the most life from its batteries' component cells. Every time a Makita battery goes back to the charger for more juice, the charger "remembers" which battery it is, senses how it's been drained, and checks the data against the battery's entire charging history. The charger then optimizes the charge -- filling each cell only as much as it needs by monitoring overall temperature, time, and individual cell temperature.

Counters and Meters. Electrical contacts serve as "check engine" lights to alert users when a tool needs attention. Bosch's Service Minder light tells a user when the carbon brushes in its rotary hammers have 8 hours of life left. After that, a spring-activated fail-safe disables the tool before its internal parts are ruined. Hitachi's model DH50MB hammer has a similar feature. Both work on the same principle as disc brakes: As the brushes wear, they expose a copper wire in the brush assembly. Once exposed, the wire completes a circuit and lights a warning light. This seems better than guessing when the brushes need to be replaced. It also takes less time than opening the tool and looking.

Signal Sensors. A feature in Metabo's model SBE808 Contact hammerdrill and model BHE6021 Contact rotary hammer senses grounded electrical conductors like water pipes or live wires. The tool does this by passing a .16 milli-amp current through the bit. When a grounded conductor completes the circuit, the tool immediately shuts off.

A similar feature rides shotgun on the Kango 240 rotary hammer's side handle. The handle houses a sensor that registers metallic items like re-bar, metal studs or copper pipes. It also detects live wires and signals their presence with a light: red for solid items, yellow for electrical lines.

And a safety device called SawStop may add the ultimate smart feature to power saws. The device electronically senses when a user's finger contacts the blade, triggering a super-fast brake that stops the blade within 1/4 of a revolution. The SawStop electrically charges a saw's blade with a low-voltage current, then monitors the charge by watching for rapid drops in amplitude. When the blade contacts wood, it works normally. But when a finger touches the blade, the human body's conductivity causes a sharp drop in amplitude and the device jams a piece of plastic into the blade. It stops in milliseconds and your fingers stay on your hand, where they belong.

Future Features

Like many advancements that find their way into tools, technology already exists to make them smarter. So don't be surprised to see things like pneumatic nailers with "odometers" that count the nails you use, or computer-controlled generators that gauge and produce only the power you need, or even tool-mounted 3D radar readouts of what's lurking inside walls or floors. Some European tools already use microprocessors to sense the electronic environment around them. That keeps their electrical fields from interfering with sensitive electronics. All these developments make sense, given the role technology plays in every other aspect of our lives. But how quickly new features find their way into your toolbox remains to be seen.