ConceptDraw
DIAGRAM 17

# Pulses

A pulse or a pulse signal is a surge of current, voltage, or electromagnetic field energy. It is a unidirectional, non-sinusoidal and not symmetrical signal. A pulse shape changes as a result of a sudden rapid change of a value from the baseline to a higher or lower one. In a certain period it returns to the baseline value. A series of continuous pulse signals, fixed-width electrical pulses or light pulses is called a pulse train or a pulse wave and is a periodic version of the rectangular function.

The electrical pulses can take a wide range of shapes: rectangular, triangular, bell, staircase, zigzag, or spire. The rectangular pulses are the most common. Pulses can transform a waveform or amplitude from one shape to another and distort the transmission of an electrical signal. The average level of a rectangular pulse wave is given by the duty cycle. Each of the pulses is placed on one of two discrete levels of amplitude.

The pulse signals are classified by count, duration or width, interval, and regularity. There are successive pulses generated repeatedly in succession and single pulses generated only once when an event occurs. The pulse duration is the period when pulses are turned on, it can differ from 0.1 second to several seconds. The time interval between turning on and off the repeated pulses is also significant. As for regularity, pulses can occur with a certain regularity or completely irregularly.

The pulses have a wide application in electronics, computer systems, physics, chemistry, medicine, and other fields. They are used in various types of motors to control driving by outputting signals in stepping motors and servo motors or measure various metrics using input signals, for example, to measure motor speed through the use of a rotary encoder. The pulses help to detect a fault in the devices or confirm their proper operation. Pulse waves are also used in synthesizers and their programming. The pulse width of the oscillator output or the duty cycle determines the shape of the wave. The modulation of the duty cycle in synthesizers helps to get a more dynamic timbre.

In common, the pulse generators are voltage sources. Simple pulse generators have a limited number of functions. They control the pulse frequency or repetition rate, pulse width or duration, the high and low voltage levels of the pulses, and delay concerning an internal or external trigger. The pulse width can range from 1 picosecond to a few minutes. Complex pulse generators provide more functions and allow controlling the rise time and fall time of the pulses.

Most pulse generators are single-channel and provide one frequency, delay, width, and output. But there are also multi-channel pulse generators, which produce multiple channels of various widths, delays, outputs, polarities, and even different repetition rates for each channel in some cases. The multi-channel generators are used to synchronize, delay, gate, and trigger the electronic devices, usually concerning one event.

The pulse generators may use digital or analog techniques, or their combination to form the output pulses. The most popular is the use of metal–oxide–semiconductor field-effect transistor (MOSFET) devices to generate the electronic pulse trains. It is reasonable due to the rapid on-off switching behavior of these electronic devices. Pulse generators are used to drive switches, modulators, intensifiers, lasers, optical components, and resistive loads. The output of a pulse generator is also used as the modulation signal for a signal generator.

Optical pulse generators are the lighting equivalent to electrical pulse generators. The light, for example, from a laser diode or a LED is their output. These generators control rate, delay, width, and amplitude.

Microwave pulse generators are devices generating ultra-short pulses with widths over 100 picoseconds. Typically, they apply the Step recovery diode (SRD) or Nonlinear transmission line (NLTL) methods. SRD-based pulse generators are inexpensive and easier to manufacture, but require several volts of input drive level and have a level of random jitter higher than NLTL-based pulse generators.

Pulse modulation allows transmitting and generating electrical signals according to pulse changes. The most effective methods for motor control are Pulse width modulation (PWM) and Pulse amplitude modulation (PAM). The PWM method is used to control the current and voltage depending on the pulse width and interval. The PAM method allows controlling the current and voltage to pass depending on the pulse strength or amplitude.

Pulse code modulation (PCM) and pulse density modulation (PDM) are methods to convert analog signals like sound and video to digital signals. PDM method enables conversion with higher sound quality than the PCM.

Pulse position modulation (PPM) method converts signals to temporal pulse phase differences and is used in thyristor drives applied to adjust lighting, the temperature of heat sources, etc.

The pulse circuit is designed to produce electrical pulses, amplificate and transform them. Pulse circuits are widely used to develop various devices like electronic switches, electronic watches, alarms, electronic toys, electronic medical devices, household appliances’ timers, etc.

Example 2. Pulses Library Design Elements

Electronic Block Diagrams solution developed for ConceptDraw DIAGRAM software includes a collection of design elements libraries and samples of Electronic circuits and Electronic block diagrams of any complexity. Electronic Block Diagrams solution includes 8 libraries:

• Amplifiers
• Delay Elements
• Electric Filters
• Electronic Blocks
• Power Convertors
• Pulses
• Repeaters
• Waveforms

The symbols appropriate to all variety of pulses types you can find in the design elements — Pulses library. These include the symbols for the oscillating pulse, rectangular pulse, amplitude modulated pulse, phase modulated pulse, long pulse, positive rectangular pulse, negative rectangular pulse, sinusoidal pulse, amplitude modulated pulse, ladder pulse, acicular pulse, phase modulated pulse, pulse width modulated, step positive pulse, and step negative pulse.

Example 3. Electronic Block Diagrams Solution in ConceptDraw STORE

The Electronic circuits and Electronic block diagrams samples you see on this page were created in ConceptDraw DIAGRAM software using the drawing tools of the Electronic Block Diagrams Solution. These examples successfully demonstrate the solution's capabilities and the professional results you can achieve using it. An experienced user spent 5-10 minutes creating each of these samples.

Use the drawing tools of the Electronic Block Diagrams solution to design your own Electronic block diagrams and Electron circuits infographics quick, easy, and effective.

All source documents are vector graphic documents. They are available for reviewing, modifying, or converting to a variety of formats (PDF file, MS PowerPoint, MS Visio, and many other graphic formats) from the ConceptDraw STORE. The Electronic Block Diagrams Solution is available for ConceptDraw DIAGRAM users.

ConceptDraw
DIAGRAM 17