Encyclopedia of electronics download

I also love the sense of humor. It's very good at disarming the fear. And it's gorgeous. I'll be recommending this book highly. With Make: Electronics, you'll start working on real projects as soon as you crack open the book. Explore all of the key components and essential principles through a series of fascinating experiments.

You'll build the circuits first, then learn the theory behind them! With the exception of the 4. The fuses through-hole component.

A selection of automotive fuses is shown in Figure The approximate physical sizes of commonly used small glass or ceramic cartridge fuses are shown here with the codes that are often used to identify them. Fuses may be fast acting, medium acting, or slow- blowing, the last of which may alternatively be referred to as delay fuses. Extra-fast—acting fuses are available from some manufacturers.

The term Slo-Blo is often used but is actually a trademark of Littelfuse. None of the terms describing the speed of action of a fuse has been standardized with a specific time or time range.

Some cartridge fuses are available in a ceramic format as an alternative to the more common Figure Three automotive fuses. All have the same rating: 30A at 32V. The largest fuse from the previous figure, cut open to reveal its element. Two blade-type fuses, commonly used for au- ment is added, it may be protected by an inline tomotive applications, shown with an inline fuse holder.

This The plastic cap, at right, is closed over the holder when a fuse has been installed. Similar inline fuse holders are manufactured for other types of fuses. A strip fuse is shown in Figure This strip fuse is intended for use in diesel ve- hicles. The example shown is rated A at 36V. All have slow-blowing characteristics. It can be thought 24 Encyclopedia of Electronic Components Volume 1 www.

Three subminiature fuses terminating in wire leads. From left to right: 10A at V, 2. Three through-hole examples are shown in Figure Some through-hole resettable fuses. See text settable fuses may be identical in size. The one for details. The fuse at the top back completely to its original value for more is rated 1A at V. This is known as tripping the fuse. While parable to the time taken for a slow-blowing fuse conventional appliance and electronics fuses to respond.

A small current still passes Centigrade. In other words, a fuse that is rated for through the component, sufficient to maintain 4A at 25 degrees may tolerate a maximum of only its amorphous state until power is disconnected. Chapter 4 25 www. It is rated for V and has an internal resistance of 50 ohms. Its hold current is 0. The three curves give a very approximate idea of the temperature sensitivity of three types of fuses commonly used to protect electronic equipment.

The left- hand scale provides an approximate value for the amper- age which will trip the fuse. A surface-mount resettable fuse. See text for details. Conventional slow-blowing fuses are temperature-sensitive, but to a lesser degree How to Use it than resettable fuses. Any equipment that may be plugged into a wall Resettable fuses are used in computer power outlet should be fused, not only to protect its supplies, USB power sources, and loudspeaker components but also to protect users who may enclosures, where they protect the speaker coils open the box and start investigating with a from being overdriven.

They are appropriate in screwdriver. They are available in surface-mount SMT couple of seconds. Other fuses will not. These fuses have a thick brass tab at each fuse.

See Panel mounted fuse enclosure is probably the Figure The cap either subminiature fuses. The fuse Repeated Failure is dropped into the tube, and the cap is applied. When a fuse in a circuit blows frequently, this is This type of holder is available in full-length or known as nuisance opening.

This is likely to change the rating of the fuse. A low-profile panel-mounted fuse holder shown disassembled left and assembled right. Chapter 4 27 www. Usually a spring restores the button to its original position when external pressure is released. At top is a normally-open single-throw pushbutton. At bottom is a double-throw pushbutton. Unlike a switch, a basic pushbutton does not have a primary contact that can be identified as the pole.

However, a single pushbutton may close Figure Commonly used schematic symbols to repre- sent a simple pushbutton. Commonly used schematic symbols to repre- sent a double-pole pushbutton.

The simplest, traditional form of pushbutton, in which pressing the button creates a connection be- tween two contacts. On-Off Behavior Figure Cross-section of a pushbutton showing two Parentheses are used to indicate the momentary spring-loaded contacts and a single return spring. It will return to the other state by default. Abbreviations that identify the number of poles This is sometimes described as a make-to- and contacts inside a pushbutton are the same make connection, or as a Form A pushbutton.

A few examples will make Contacts are normally closed by default, and this clear: are open only while the button is pressed. When the button is pressed, the first set of contacts 30 Encyclopedia of Electronic Components Volume 1 www. This is examples are fairly typical. NO may be used to describe it as normally closed or normally open. Contacts on the rod rub across secondary contacts inside the enclosure.

However, it can only tolerate low currents, has limited durability, and is vulnerable to contamination. A four-pole, double-throw pushbutton is shown in Figure Left: schematic symbol for a simple SPDT slide pushbutton, where a movable contact shorts togeth- actuator.

Right: A 4PDT pushbutton in which the same principle has been extended. The movable contacts are attached to each other mechanically by an insulator. Each pole terminal is marked with a P.

Styles Many pushbutton switches are sold without caps attached. This allows the user to choose from a selection of styles and colors. A 4PDT slider pushbutton, shown without the cap that can be snapped onto the end of the actuator. The lead that wired to activate the light when the button is functions as a pole is marked with a P in each pressed, when it is released, or on some other case.

Pushbuttons containing LEDs usually Chapter 5 31 www. This pushbutton contains an LED underneath the white translucent button. Caps buttons or knobs that may be sold as separate accessories for some pushbuttons, shown here This style is shown in Figure After the component has been installed in used. An example of an illuminated pushbutton is it when the device is assembled, or an external shown in Figure However, about one-quarter of tactile switches are designed for Termination and Contact Plating surface mount at the time of writing.

They are These options are the same as for a switch and typically found beneath membranes that the are described in that entry. The first press causes contacts to latch in the closed state. The second press returns the contacts to the open state, after which, the process repeats.

However, buttons that behave Figure At right, a simple DPDT latching pushbutton this way are not always identified as doing so on with lockdown. A six-pole double-throw pushbutton that latches controller toggles an output between two states.

Examples are found on cellular phones or portable media players. Foot Pedal Foot pedal pushbuttons generally require more actuation force than those intended for manual Figure This 6PDT pushbutton latches and then un- latches, each time it is pressed. They are ruggedly built and are commonly found in vacuum cleaners, audio-transcription Two more variants are shown in Figure More often, the buttons are matrix encoded, meaning that each of them bridges a unique pair of conductors in a matrix.

A button matrix is shown in Figure The keypad on the left is matrix-encoded, and is polled via seven through-hole pins that protrude ably when no signal is present. The keypad on the right assigns each button to pearance of two keypads is shown in Figure See the text for details about matrix encoding. A typical tactile switch. Buttons in a numeric keypad are usually wired as a matrix, where each button makes a connection Membrane Pad between a unique pair of wires.

This system is suitable for Typically found on devices such as microwave being polled by a microcontroller. It is almost always a SPST device available as generic off-the-shelf components. Tactile switches may be PC- tion websites. An example is shown in Figure If one button is pressed, it latches. The buttons can be pressed in any sequence. Pushbutton current ratings range from a few mA This system is useful for applications such as to 20A or more. Many pushbuttons have their component selection in a stereo system, where current ratings printed on them but some do not.

However, snap-action switches are chanical component, a pushbutton is vulnerable almost always single-pole devices. When a pushbutton controls a device that has a high inductive load, a snubber can be added to minimize arcing.

Caps are often sold separately and may not be interchangeable between switches from different manufacturers. A pushbutton mounted on top of a SPDT snap-action switch.

Consider applying a drop of Loc-Tite or Briefly touching the power to the LED terminals, similar adhesive before completely tightening through the resistor, should cause the LED to the nut. Although there is some overlap of function, rotary switches and pushbuttons have their own separate entries. Integrated-circuit switching devices will be found in Volume 2. Multidirectional switches differentiate up, down, left, right, diagonal, rotational, and other finger inputs, and are not included in this encyclopedia.

Schematic symbols for the most basic type of on-off switch are shown in Figure The two most common schematic symbols for a SPST switch, also known as an on-off switch. The The most fundamental type of switch is a knife symbols are functionally identical. Switches with more than 4 poles are electrical supply panels, where the large contact uncommon. If there is only one pole, this is a single-pole switch. If there is an additional pole, electrically isolated from the 37 www.

Usually a movable contact is attached to it internally, to touch the secondary contact, also known as a stationary contact when the movable contact is flipped to and fro. Poles and Throws Abbreviations identify the number of poles and contacts inside a switch. In Figure , schematic symbols are shown for A double-throw switch may have an additional double-throw switches with 1, 2, and 3 poles. The center position. Variants Float switch, mercury switch, reed switch, pressure switch, and Hall-effect switch are considered as sensing devices, and will be found in Volume 3.

Terminology Many different types of switches contain parts that serve the same common functions. Schematic symbols to represent three types of double-throw switch. Top left: Single-pole. Bottom left: tact inside a switch is connected with the pole of Double-pole.

Right: Triple-pole, more commonly known as 3-pole. NONE, assuming that if the word is omitted, a center position does not exist. This is known as a break before position.

Also known as a limit switch and sometimes as a microswitch or basic switch. This utilitarian design Parentheses are used in descriptions of spring- is often intended to be triggered mechanically loaded switches to indicate a momentary state rather than with finger pressure, for example in that lasts only as long as pressure is applied to 3D printers.

It is generally cheap but reliable. A sectional view of a snap-action ON- and returns to that position when pressure ON limit switch is shown in Figure The pole is released. The strip has a cutout which allows an button and is sometimes described as a inverted U-shaped spring to flip to and fro. It make-to-make connection. This is sometimes described as a make-to-break connection. Chapter 6 39 www. The body of the switch is sealed, with a small button protruding through a hole.

A thin metal arm may provide additional leverage to press the button. A roller may be Figure Two SPDT snap-action switches, also known mounted at the end of the arm so that the switch as limit switches. The one on the right is full-size. The one can be activated as it slides against a moving on the left is miniature, with an actuator arm to provide mechanical component such as a cam or a wheel.

The arm may be trimmed to the re- quired length. The switch is commonly used to limit the travel or rotation of such a component. Subminiature snap-action switches can often be actuated by a pressure of only a few grams.

Rocker Three rocker switches are shown in Figure A sectional view of a rocker switch is shown in Figure In this design, a spring-loaded ball bearing rolls to either end of a central rocker arm when the switch is turned. Rocker switches are often used as power on-off switches. Slider Many types of slider switch also known as slide switch are widely used as a low-cost but versatile way to control small electronic devices, from clock-radios to stereos.

The switch is usually mounted on a circuit board, and its knob or cap protrudes through a slot in the panel. It is usually cheaper than a toggle switch but is seldom designed for use with a high current. Here again, there is no pole. Three rocker switches, the upper two de- signed for push-insertion into a suitably sized rectangular hole in a panel. The switch at front-center is intended to be screwed in place, and is more than 20 years old, show- ing that while the choice of materials has changed, the ba- sic design has not.

This subminiature slide switch is less than half an inch long, rated 0. Larger versions look almost identical, but can handle only slightly more current. The representation of sliders in schematics has not been standardized, but the samples shown are common. Two full-size, heavy-duty toggle pole is identified with letter P in each case. Top switches are shown in Figure Bottom left: There switch is shown in Figure Toggle switches are no poles in this switch, as such.

The slider can with more poles are extremely rare. Chapter 6 41 www. Two full-size toggle switches capable of han- dling significant current. At left, the switch terminates in quick-connect terminals. At right, the switch has solder terminals some of them containing residual traces of sol- der. Slide switch schematics. Each black rectan- gle represents a movable contact that connects two pairs of fixed contacts at a time. Detailed commentary on these variants will be found in the body of the text.

Manufactur- ers may use variants of these symbols in their datasheets for example, the gray rectangle indicating an insulating contact carrier, at top right, may be represented as a sin- gle line, or a black outline with a white center. Four-pole switches are relatively unusual. Three miniature toggle switches with current ratings ranging from 0. Each small square in the background grid measures 0. A toggle switch intended for control of auto- motive accessories. An automotive toggle switch is shown in Figure A rubber or vinyl boot can be used to protect a toggle switch from contamination with dirt or water.

Each boot contains a nut that screws onto the threads of a toggle switch, as shown at left. The toggle then snaps back into Figure The interior connections of a pin DIP place, usually engaging in a small slot in the switch.

SPST DIP switches circuit board, either in through-hole or surface- are made with 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, and 16 mount format. Through-hole DIP switches have positions. Surface-mount DIP switches as installing an additional disk drive. While this may have 0.

Because of the The switch positions are usually labelled ON and 0. Chapter 6 43 www. Most DIP switches have wire terminals which are One terminal of each switch usually shares a just long enough for insertion into a standard common bus. Pin spacing is 0. DIP switch package options include standard, low-profile, right-angle standing at 90 degrees relative to the circuit board , and piano with switch levers designed to be pressed, like tiny rocker switches, instead of being flipped to and fro.

A surface-mount, 0. Some toggle-switch bodies are also sold with paddle-shaped actuators. The cover has been removed at right.

The applications for SIP switches are the Figure A subminiature paddle switch. Full-size ver- sions are often used as power switches. This style is also known as a page This termination style bushing that is inserted from behind the front is known as right-angle PC. Many manufacturers panel of a product, through a hole of appropriate offer a choice of straight or bent pin terminals, size.

It is supplied with a lockwasher and a nut but the component may be listed in a catalog often, two nuts that fit the thread on the switch under either of those options, with no indication bushing. This mounting style is mostly minals that can also function as solder lugs are used for rocker switches and sometimes for slide sometimes offered as an option.

The actuator of the switch is accessible stripped and tinned ends, protruding at least an through a cutout. The internal electrical contacts of a switch are usually plated with silver or gold. Nickel, tin, and PC mount switches have pins that are soldered silver alloys are cheaper but less common. Other into a printed circuit board. Values Surface mount switches are attached to a board in the same manner as other surface-mount Switches designed for electronic devices vary components.

Rocker switches, paddle switches, and toggle switches are often used to turn power on and off, and are typically rated for 10A at VAC, Chapter 6 45 www.

Slide switches cannot handle significant power, and are often rated around 0. Generally they are used only when the power to the device is off. The primary reason Figure In this schematic, normally-closed limit for following this convention is that it is widely switches are opened by pressure from an arm attached to a motor, thus switching off its power at each end of its used; thus, following it will reduce confusion.

A two-coil latching relay activates the motor. If you have any doubts about these concepts which go beyond tion indefinitely without drawing power. When the scope of this book , consult a reference guide the upper coil of the relay receives a pulse from on this subject. The ground wire of an AC supply should lower terminal of the motor.

The motor turns never be switched, because the device should clockwise until the arm attached to its shaft hits always be grounded when it is plugged into an the lower limit switch and opens it. Limit Switches When the lower coil of the relay is activated, the An application for two limit switches with a DC relay flips to its lower position.

Positive current motor and two rectifier diodes is shown in can now reach the upper side of the motor Figure The motor runs tor turns clockwise when its lower terminal is counter-clockwise until its arm opens the upper positive, and counter-clockwise when its upper limit switch, at which point the motor stops terminal is positive. Only two terminals are used again. This simple system allows a DC motor to and shown in each limit switch; they are chosen be run in either direction by a button-press of any to be normally-closed.

It has been used be ignored. However, in this scenario, sustained pressure more ubiquitous, they have taken over many on the pushbutton would be necessary to move functions in electronic products that used to be the motor arm all the way to the opposite end of served by switches. A menuing system driven by its travel. Whether it is easier to use is tom, as shown in Figure Either switch will a matter of taste.

Cost and ergonomics may be turn the light on if it is currently off, or off if it is the primary factors to consider when choosing currently on. The most common cause is an inductive load that generates back-EMF when it Figure SPDT switches are commonly used in house is switched on and forward-EMF when it is wiring so that either of them will turn a shared light on if it switched off. The surge can be many times the is off, or off it is on. This is often referred to as a flyback diode or freewheeling diode.

In AC circuits, where a diode cannot be used in this way, a snubber a simple combination of capacitor and resistor may be placed around the load. A DPDT switch must be inserted if three switches must have identical function to control the on-off state of a single light bulb. Chapter 6 47 www. Dry Joints Part numbers generally include codes to identify Switches that control significant current will have each terminal variant, and should be studied substantial terminals, and these terminals will be carefully.

For this reason, various strategies are used ance and will be mechanically weak, liable to to debounce a switch that drives a logic input. Friction is also an issue inside these can be a significant hazard. Heat-shrink tubing switches, as the design often entails the rounded should be applied to enclose wires and terminals tip of a lever rubbing to and fro across the center at the rear of a power switch, as an additional of a movable contact.

Power switches should always be used in conjunction with appropriate fuses. The spring inside a snap switch or limit switch may fail as a result of metal fatigue, although this Contact Contamination is rare.

Slide changes position. Switches may be supplied with pins for the component to fall inside its enclosure. Variants may also be available for surface components where the threads are molded into 48 Encyclopedia of Electronic Components Volume 1 www. Consider applying a drop of Loc-Tite or other, even at opposite sides of the page, for similar adhesive after moderately tightening the convenience in drawing the schematic.

Dotted nut. Note that nut sizes vary widely, and finding lines usually, but not always, link the poles. In the a replacement may be time-consuming. For Cryptic Schematics example, SW1 a and SW1 b are almost certainly In some circuit schematics, the poles of a multi- different parts of the same switch, with linked pole switch may be visually separated from each poles. Chapter 6 49 www. The colors were chosen to differentiate the parts more clearly, A rotary switch makes an electrical connection and do not correspond with colors in an actual between a rotor, mounted on a shaft that is switch.

Typical schematic symbols for a rotary switch. Also, while the output from a rotational encoder must be decoded and interpreted by a A selection of rotary switches is shown in device such as a microcontroller, a rotary switch Figure This type of component is now rare.

At top-right is a twelve-position, single-pole switch rated 2. At front-left is a four- Two typical schematic symbols for a rotary switch position, single-pole switch rated 0. They are functionally or VAC. At front right is a two-position, two- identical. All the sealed switches allow a choice of Figure A selection of rotary switches. See text for de- Figure A simplified rendering of interior parts in a ba- tails.

Arbitrary colors have been added for clarity. If there is more than or four rotors, pointing in different directions, one deck, they are spaced from each other by may be combined on a single deck if the switch about 0. It has five poles one per deck , and This is typically a pin, which may be attached to a maximum of 12 positions. The pin is inserted into a choice of holes ponent is becoming relatively rare. For example, an eight-position rotary If the rotor in a switch establishes a connection switch can be configured so that it has only seven with the next contact a moment before breaking or as few as two available positions.

In a cludes the angle through which the switch turns nonshorting or break-before-make switch, a tiny between one position and the next. In a panel-mount design, a nut is tightened around a thread on the bushing of the switch. It is described in the switch entry of this encyclopedia. A rotary DIP switch also known as an encoded output rotary switch or a coded rotary switch does not conform with a DIP layout, despite its name.

It is approximately 0. A five-pole, twelve-position rotary switch. The pins This can be of significant importance, depending are spaced at 0. Pin on the components that are connected with the function and layout are not standardized. A dial on top of the switch has either 10 positions The shaft may be round, splined, or D-shaped in numbered 0 through 9 or 16 positions 0 section.

A knob is seldom supplied with a switch through 9 followed by letters A through F. One and must be chosen to match the shaft. Some switch of each type is shown in Figure It is more likely to be a ed on the face of the panel.

Miniature rotary switches may be as small as 0. Miniature with a unique binary pattern, this is an example switches usually have lower current ratings than of absolute encoding. A rotary DIP switch, also known as an enco- ded output rotary switch, may be used as a substitute for a DIP switch in some applications. In the complement-coded version, the output is inverted. A six-pin rotary DIP variant is available from some manufacturers, with two rows of three pins, the Figure Positive and negative states of the four output pins of a real-coded position rotary DIP switch, assum- two center pins in each row being tied together ing that the common pin of the switch is connected with a internally, and serving as the pole of the switch.

A ten-position rotary DIP switch would use only the states from 0 through 9. In a Rotary DIPs are available with a screw slot, small complement-coded switch, the positive and negative knurled knob, or larger knob. The output, using a series of nonsequential binary switch on the left in Figure is of this type. Such a series is useful because it ponents, surface-mount versions are available. The Grayhill Series 51 allows Typically, a microcontroller must use a lookup 12 positions, each generating a code among four table to convert each binary output to an angular terminals.

A single- ment, often in industrial process control. Its contacts are rated to carry 0. A button above the wheel, marked with a minus sign, rotates it to the next lower number, while a button below the wheel, marked with a plus sign, rotates it to the next higher number. A connector at the rear of the unit includes a common input pin and four output pins with values 1, 2, 4, and 8.

The states of the output pins sum to the value that is currently being displayed by the wheel. Often two, three, or four pushwheels each with an independent set of connector pins are combined in one unit, although individual pushwheels are available and can be stacked in a row. A thumbwheel switch operates like a pushwheel switch, except that it uses a thumbwheel instead of two buttons.

This miniature switch is designed for insertion on a printed circuit board. It can be used to make a setting Hexadecimal versions are also available, with before a device is shipped to the end user. Chapter 7 55 www. Values A full-size rotary switch may be rated from 0. A resistor ladder can be formed around the contacts of a rotary switch, with the pole of the switch How to Use it connected to a microcontroller that has an analog-digital converter built in.

The microcontroller converts the volt- In addition to its traditional purpose as a mode age input to an internal digital value. Thus, one pin can or option selector, a rotary switch provides a sense as many as twelve input states. Three ten- might require other values. A pullup resistor of perhaps An analog-digital converter inside er.

The advantage of this scheme is ler. This option is found on devices ranging from that it allows very rapid control by the user, while digital alarm clocks to cellular phones. The specifications for a particular microcontroller 56 Encyclopedia of Electronic Components Volume 1 www. Any switch with exposed contacts be briefly connected with the adjacent terminal will be especially vulnerable to dirt and moisture, while the switch is being turned.

Exposed contacts are also more vulnerable to User Abuse side-effects from temperature cycling when a The turning force that must be applied to a full- device warms up and then cools down. If the switch is not secured discussed in that entry in this encyclopedia. Chapter 7 57 www. Cheaper, simpler, electromechanical devices were properly referred to as control shaft encoders.

However, the term rotational encoder is now applied to almost any device capable of converting rotational position to a digital output via opening and closing internal mechanical contacts; this is the sense in which the term is used here.

Magnetic and optical rotary encoders do not contain mechanical switches, are classified as sensors by this encyclopedia, and will appear in Volume 3. They are found in a device such as an optical mouse. A rotational encoder has a knob that a user can turn to display a series of prompts on an LCD How It Works screen, or to adjust the input or output on a product such as a stereo receiver.

Thus, this type of encoder ence. The microcontroller can identify each absolute rotational position. The two buttons inside the dashed line represent the two pairs of contacts inside the encoder, while the chip is a microcontroller. The knob and shaft that activate the internal switches are not shown. The schematic assumes that when a contact closes, it pulls the chip input to a low state. Simplified schematic showing the typical set- up for a rotational encoder. The pushbuttons inside the dashed line represent the contacts inside the encoder.

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