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Circuit Cellar's editorial team comprises professional engineers, technical editors, and digital media specialists. You can reach the Editorial Department at editorial@circuitcellar.com, @circuitcellar, and facebook.com/circuitcellar

Interconnect Defects (ICDs) Explained

What is an Interconnect Defect (ICD)? An ICD is a condition that can interfere with the internal circuit connections in a printed circuit board (PCB). These internal connections occur where the innerlayer circuit has a drilled hole put through it. PCB processing adds additional copper into the drilled hole to connect the innerlayer circuits together and bring the circuit to the PCB board surface where connectors or components are placed to provide final function.

If there is a defect at or near this interconnect or plating and innerlayer copper, it could lead to failure of a specific circuit (or net). This defect typically causes open circuits, but could be intermittent at high temperatures. Of significant concern is that the functionality may be fine as the PCB is built, but will fail in assembly or usage, becoming a reliability risk. This latency for the defect has put ICDs on the serious defect list in the industry. Another item is that ICDs have increased in frequency over the past five to seven years, making this a higher priority issue.

The majority of ICDs fall into two categories: debris-based ICDs and copper bond failure ICDs. Debris-based ICDs are caused by material left behind by the hole drilling process. This material is supposed to be removed from the holes, but is not when ICDs are found. Some causes are drill debris residues, drill smear and particles (glass and inorganic fillers) embedded into the innerlayer copper surface. The increases in this ICD type seems to be related to the increased usage of low Dk/low Df materials that use inorganic filler types. These materials generate more drilling debris and are often more chemically resistant materials, compared to standard FR-4 epoxy materials. This combination of effects makes the drilled holes much more difficult to clean out completely.

Debris-based ICD

Debris-based ICD

Copper bond failure ICDs occur when the copper connection is physically broken. This can be due to high stress during assembly or use, or the copper bond being weak (or a combination). This failure mode is also design related, in particular, increased PCB thickness, increased hole size and wave soldering all tend to increase the risk of copper bond ICDs. It seems that there has been an increase in the rate of this ICD type, which is related to increased lead-free soldering temperatures and increased board thickness over the past 10 years. Note: This condition also occurs on HDI microvias. The causes are similar but the processing is different.

Copper bond failure ICD

Copper bond failure ICD

Reliability testing has been run on both types of ICDs. Copper bond type ICDs are a significant reliability issue. They show up as assembly failures and product with weakness may have increased tendency for field failures. Drill debris type ICDs have not been shown to be a significant reliability issue in several studies, but they are an industry specification failure, so they affect product yield and costs. Well run IST testing, using a valid coupon structure, has been a very valuable testing method for determining risk due to ICDs.

ICDs can be prevented by good PCB design and improved PCB processing methods. Debris type ICDs are a function of drilling parameters and desmearing. Many of the newer materials with fillers do not drill like standard FR-4. Instead of forming a chip during drilling, they break apart into small particles. These particles then tend to coat the drilled hole walls. One factor associated with debris ICDs is drill bit heating. Factors that result in hotter drill bits cause more debris formation and residues.
Desmearing, which is done to remove drilling residues, often needs to be more aggressive when using these material types. This has been effective at reducing or eliminating debris ICDs.

Copper bond failures are a little more complex. In PCB processing, the key factors are cleaning the innerlayer copper surface so that a strong bond can form. In addition, the electroless copper deposit needs to be in good control, having the correct thickness and grain structure, to have the required strength. Testing and experience show a good processing focus, along with appropriate reliability testing can result in consistently robust product.

Design factors also play a big role. As noted above, board thickness and hole size are key factors. These relate to the amount of stress placed upon the interconnect during thermal exposure. Eliminating soldered through-hole connectors is one of the major ways to reduce this issue, as these often contain most of the larger holes. If you need to have thick boards, look into the z-axis CTE and Tg of your material. Lower z-axis CTE values and higher Tg values will result in reduced stress.

With PCB performance requirements constantly on the rise, ICDs will remain an issue. A better understanding of ICDs will help designers reduce the impact that they have on the performance of the board. Better PCB processing practices in drilling and desmear and selecting electroless copper will improve quality. Implementing best practices will reduce opportunities for ICDs, particularly changing connector approaches. Finally, this issue is taken seriously by the PCB suppliers, many of which are working to combat the sources behind ICD failures.

Doug Trobough is the Corporate Director of Application Engineering at Isola Corp. Doug has worked introducing new material introduction and PCB processing enhancement with Isola for five years. Prior to Isola, Doug had almost 30 years of experience building a wide variety of PCB types and interconnections systems, for Tektronix and Merix Corp., in a variety of technical positions, including CTO for Merix Corp. 

This essay appears in Circuit Cellar 300 (July 2015).

Multi-Touch Solution Brings Modern UI Elements to Embedded Designs

Microchip Technology recently announced a new addition to its Human Interface Solutions portfolio. The MTCH6303 is a turnkey projected-capacitive touch controller for touch pads and screens. Touch sensors with up to 1,000 nodes and diagonals of up to 10” are supported. The MTCH6303 provides multi-touch coordinates as well as a ready-made multi-finger surface gesture suite that brings modern user interface (UI) elements (e.g., pinch and zoom, multi-finger scrolling, and swipes) to any embedded design, with minimal host requirements.Microchip MTCH6303

The MTCH6303’s advanced signal processing provides noise-avoidance techniques and predictive tracking for 10 fingers, at scan rates of up to 250 Hz with a minimum of 100 Hz each for five touches. It also combines with Microchip’s MTCH652 high-voltage line driver to achieve a superior signal-to-noise ratio (SNR) for outstanding touch performance in noisy environments.

When combined with the MGC3130, the MTCH6303 solution can support 3-D air gestures up to 20 cm from the touch panel. Microchip’s MGC3130 E-field-based 3-D tracking and gesture controller includes Microchip’s GestIC technology, allowing user input via natural hand and finger movements in free space. Thus, you can create interface-control possibilities in two and three dimensions.

The advanced capabilities of the MTCH6303 create robust, ready-to-go touch and gesture solutions for the rapid growth of human-interface applications and requirements in the industrial (e.g., machine control panels), home automation (e.g., lighting controls) and office equipment (e.g., printers) markets, among others.

The MTCH6303 is supported by Microchip’s new $149 Multi-Touch Projected Capacitive Touch Screen Development Kit (part # DV102013), which is now available with free, downloadable software. The DV102013 incorporates the MTCH6303 projected-capacitive touch controller and the MTCH652 high-voltage driver on a controller board, and includes a transparent, 8″ ITO touch panel for easy demonstration of the MTCH6303’s touch-controller capabilities and supporting graphical user interface (GUI) functionality.

Microchip’s free MTCH6303 GUI provides you with complete access to the configuration and tuning parameters. Advanced visualization windows assist all user levels with easy-to-comprehend feedback, to accelerate design integration for fast time-to-market.

Additionally, Microchip empowers designers by providing access to the firmware library, to enable further customizations for maximum design flexibility and control.

The new MTCH6303 is available today in 64-pin QFN and TQFP packages, for sampling and volume production. Pricing starts at $2.46 each, in 10,000-unit quantities.

The MTCH652 is available today in 28-pin QFN, SOIC and SSOP packages, for sampling and volume production. Pricing starts at $1.04 each, in 10,000-unit quantities. The MGC3130 is available in a 28-pin QFN package for sampling and volume production. Pricing starts at $2.26 each in 10,000-unit quantities.

Source: Microchip Technology

STMicro Introduces STM32F7 MCUs with Advanced ARM Cortex-M7 Core

STMicroelectronics has begun producing microcontrollers with the new ARM Cortex-M7 processor, which is the newest Cortex-M core for advanced consumer, industrial, and Internet-of-Things (IoT) devices. The new STM32F7 microcontrollers combine the Cortex-M7 core with advanced peripherals. STMicro_STM32_Volume_Disc_Kit

The STM32F7 Discovery Kit includes the STM32Cube firmware library along with support from software-development tool partners and the ARM mbed online community. The $49 Discovery Kit includes a WQVGA touchscreen color display, stereo audio, multi-sensor support, security, and high-speed connectivity. In addition to an integrated ST-Link debugger/programmer (you don’t need a separate probe), you get unlimited expansion capability via the Arduino Uno connectivity support and immediate access to a wide variety of specialized add-on boards.

STM32F7 devices are available in a range of package options from a 14 mm × 14 mm LQFP100 to 28 mm × 28 mm LQFP208, plus 10 mm × 10 mm 0.65-mm-pitch UFBGA176, 13 mm × 13 mm 0.8 mm-pitch TFBGA216, and 5.9 mm × 4.6 mm WLCSP143. Prices start at $6.73 for the STM32F745VE in 100-pin LQFP with 512-KB on-chip flash memory (in 1,000-unit orders).

The STM32F7 development ecosystem includes both the Discovery Kit and two evaluation boards (STM32746G-EVAL2 and STM32756G-EVAL2) that cost $560 each. The STM32F7 Discovery Kit (STM32F746G-DISCO) gives full flexibility to fine-tune hardware and software at any time. You also benefit from the associated STM32CubeF7 firmware, and the ability to re-use all STM32F4 software assets due to code compatibility.

Source: STMicroelectronics

New High-Speed CMOS DDR2 Synchronous DRAMs

Alliance Memory recently broadened its line of high-speed CMOS double data rate 2 synchronous DRAMs (DDR2 SDRAM). Its new device featuring high 2-Gb density in a 84-ball 8-mm × 12.5-mm × 1.2-mm FBGA package. The AS4C128M16D2 is available (from a limited number of suppliers) in commercial (0°C to +85°C) and industrial (–40°C to +95°C) temperature ranges.AllianceMemory-DDR2 SDRAM

The AS4C128M16D2 provides a drop-in, pin-for-pin-compatible replacement for a number of similar solutions in industrial, auto, consumer, networking, and medical products that require high memory bandwidth. It is internally configured as eight banks of 16M × 16 bits. The RoHS-compliant DDR2 SDRAM includes a synchronous interface and operates from a single 1.8-V (±0.1 V) power supply. In addition, it features a fast clock rate of 400 MHz and a data rate of 800 Mbps/pin. The DDR2 SDRAM provides programmable read or write burst lengths of 4 or 8. An auto precharge function provides a self-timed row precharge initiated at the end of the burst sequence. Easy-to-use refresh functions include auto- or self-refresh while a programmable mode register allows the system to choose the most suitable modes to maximize performance.

With the AS4C128M16D2, Alliance Memory now offers a variety of DDR2 SDRAMs with densities of 512 Mb, 1 Gb, and 2 Gb. Samples of the AS4C128M16D2 are available now, with lead times of six to eight weeks for production quantities. Pricing for US delivery starts at $6.50 per unit.

Source: Alliance Memory

Percepio Tracealyzer – SW Tracing Tools for RTOS-Based Systems (Sponsored)

To understand what’s truly going on in your RTOS-based system, you need tools to help you understand the complex web of connections. Percepio’s Tracealyzer gives unprecedented insight into embedded software’s real-time behavior and improves your ability to deliver robust and responsive software, on time and within budget.ConnectedViews

When developing embedded software based on an operating system, a traditional debugger is often insufficient to fully understand the software’s run-time behavior. A debugger shows the current system state and allows you to step through individual functions, but this is a low-level perspective that is not suitable for studying real-time operating system behavior, such as scheduling, blocking and interactions between tasks.

Percepio Tracealyzer visualizes the run-time behavior of your embedded software through more than 20 high-level views that complement the debugger perspective with the “big picture”. You may have used some trace tool before, but this is something extra. The views are interconnected in clever ways and intuitive to use; multiple views can be synchronized and displayed simultaneously. The 20+ views include:

  • Tasks, System Calls and User Events
  • CPU Load
  • Timing Variations
  • Communication Flow
  • Kernel Object History
  • User Events and Signal Plots

Percepio Tracealyzer is available for the following Real Time Operating Systems:

  • FreeRTOS
  • embOS
  • Linux
  • VxWorks
  • On Time RTOS32

Download a full-featured Tracealyzer evaluation license.

For more information visit percepio.com or watch our FreeRTOS+Trace video.

How To Measure Temperature with a Soldering Iron

Forget those expensive temperature sensors. Now you can use an ordinary heating element like a soldering iron to measure temperature. Daniel Maliks’s upgraded soldering iron will be a great addition to your workbench.

In Circuit Cellar 191, Malik writes:

There are many applications that involve the conversion of electric current into heat by means of a heating element with some degree of temperature control. Hot water boilers, kettles, and irons are typical examples. In this article, I’ll explain how you can eliminate the need for a temperature sensor by using the heating element itself to accurately measure temperature.

dsa

The finished soldering station. Think of it as a heating element turned temperature sensor.

I appreciate that electronics enthusiasts don’t necessarily want to read about cooking and ironing. So, I’ll describe a device you might be more comfortable thinking about: a soldering iron. All of the aforementioned appliances and tools have one important thing in common that makes them different from, say, a hair dryer. Any thoughts?

The important common factor is that the thermal resistance between the heating element and the heated medium is much lower than the thermal resistance between the medium and the ambient world. Thus, if electric current stops flowing through the heating element, the temperatures of the element and the medium will equalize long before the medium loses much of its temperature via heat radiation and conduction.

Because the resistance of all the conductors used for constructing heating elements has some temperature coefficient, you can measure the temperature of the heating element by measuring its resistance and comparing it to its resistance at, say, 25°C. This brings us neatly to the basic idea behind this project.

First, you turn on the heating element for a while. Then, switch it off and wait for the temperatures to equalize. After that, you must measure the resistance and calculate the temperature. And then do it again: switch on, switch off, measure, and so on. It’s easy to see why this approach wouldn’t work with a hair dryer. The air forced through a hair dryer moves quickly and has poor heat conductivity.

I can hear you asking the obvious questions. How difficult is it to measure the element resistance? How much does it change with temperature? Wouldn’t a simple sensor be cheaper and easier to use? It depends on the application. I will address these concerns as I describe the soldering iron example.

The schematic below shows Malik’s complete application. The power supply is the only part not shown in the schematic of the soldering station. The current source is powered
by 8 V to reduce power dissipation.

In the measurement circuit, the current source is built from an adjustable linear regulator. The current is set to a little higher than 200 mA. The main power switch Q1 is connected to an additional transistor circuit to translate the control voltages down to the 0- to 5-V range the Freescale MC68HC908QT4 microcontroller is capable of generating.

The complete application, without the power supply

The complete application, without the power supply

The MC68HC908QT4 microcontroller is an inexpensive 8-bit HC08 device housed in an eight-pin DIL package that’s easy to work with. The microcontroller is connected to an LED that indicates whether the soldering tip is below, equal to, or above the desired temperature. A potentiometer regulates the desired temperature. The remaining pieces of the circuit are two trimmers that are used to calibrate the offset and gain of the temperature regulation.

A schematic of the power supply I used isn’t shown here. I used a small, lightweight custom switch-mode power supply. However, the circuit will work equally well with a mains transformer-based power supply.

This temperature measurement application is very simple. As a result, the small amount of code for the ’HC908QT4 is little more than 700 bytes.

Download the entire CC191 article.

High-Resolution Resistive Sensing Signal Conditioner

Texas Instruments recently introduced the PGA900 high-resolution resistive sensing signal conditioner. The PGA900 enables the fast and precise 24-bit measurement of conditions such as pressure, flow, strain, or liquid levels. Its programmable core enables flexible linearization and temperature compensation for numerous resistive bridge sensing applications.TI PGA900

Key features and benefits include:

  • Fast, precise sensor signal and temperature compensation: Integrates two 24-bit ADCs to provide high-resolution signal acquisition. Low-drift voltage reference of 10 ppm/°C, maximum, enables high accuracy across the –40°C to 150°C operating temperature range.
  • Integrated 14-bit DAC: Enables highly linear analog outputs.
  • User-programmable temperature and nonlinearity compensation algorithms: Integrated ARM Cortex-M0 core allows developers to use proprietary temperature and nonlinearity compensation algorithms to differentiate their end products.
  • Simple calibration: One-wire interface allows communication, configuration and calibration through the power supply pin without using additional lines.
  • Wide input voltage allows direct connection to the power supply: Integrated power management circuitry accepts input voltages ranging from 3.3 to 30 V to simplify the design and provide reliability.

With the PGA900 evaluation module (EVM), you can to quickly and easily evaluate the device’s performance and integrated features. The PGA900EVM is available for $249. You can download PGA900 example software and the user’s guide, as well as the PSpice and TINA-TI Spice and TINA-TI models, at www.ti.com.

The PGA900 resistive sensing conditioner comes in a 6 mm × 6 mm very thin quad flat no-lead (VQFN) package. It costs $4.50 in 1,000-unit quantities.

Source: Texas Instruments

New 700-V HVICs Increases System Reliability, Shrink Board Space

Infineon Technologies recently launched a family of rugged, reliable 700-V High-Voltage ICs (HVICs) optimized for solar, power supply, uninterruptible power supplies (UPS), welding, and industrial drive applications. The 700-V offering enables designers of high-voltage power stages to simplify their designs while making them more robust.Infineon-700V-HVIC

The new IR7xxxS series of HVICs feature sink/source ratings from 60 to 2,300 mA and utilize PN junction technology. Available in half bridge and high- and low-side configurations, the new HVICs are optimized for 700-V MOSFETs and 650-V IGBTs and offer full driver capability with extremely fast switching speeds to reduce magnetics component count.

Other key features of the new devices include under-voltage lock-out protection for both channels, lower di/dt gate driver for better noise immunity. In addition, the HVICs are tolerant to negative transient voltage dv/dt, offer matched propagation delay for both channels and are 3.3- and 15-V input logic compatible.

The new IR7xxxS series is available in surface-mount (8-SOIC) packages in high volume. The lead-free devices are RoHS-compliant.

Source: Infineon

Video Decoder with MIPI-CSI2 Output Interface Supports Next-Generation SoCs

Intersil Corp. recently introduced the TW9992 analog video decoder, which features an integrated MIPI-CSI2 output interface that provides compatibility with the newest SoC processors. The decoder’s MIPI-CSI2 interface simplifies design by making it easier to interface with SoCs, while also lowering the system’s EMI profile. The TW9992 decoder takes both single-ended and differential composite video inputs from a vehicle’s backup safety camera, and is the latest addition to Intersil’s video decoder product family for automotive applications.TW9992-intersil

Designed with built-in diagnostics and superior video quality, the TW9992 addresses the biggest challenges faced by automotive video systems. For example, the decoder’s Automatic Contrast Adjustment (ACA) image enhancement feature overcomes a major challenge for backup camera systems by adapting to rapidly changing lighting conditions. ACA is able to automatically boost up or reduce the brightness/contrast of an image for greater visibility and safety.

In addition, vehicle backup cameras typically employ differential twisted pair cables that require designers to use an operational amplifier (op amp) in front of the video decoder to convert the differential signal to single-ended. The TW9992 decoder eliminates the need for an external op amp by supporting direct differential CVBS inputs, thus reducing system cost and board space. The built-in short-to-battery and short-to-ground detection capability on each differential input channel further enhances video performance and automotive system reliability.

Features and specifications:

  • NTSC/PAL 10-bit ADC analog video decoder with 4H adaptive comb filter
  • MIPI-CSI2 output interface
  • Software selectable analog input control allows for combinations of single-ended or differential CVBS
  • Advanced image enhancement features: automatic contrast adjustment, and programmable hue, brightness, saturation, contrast and sharpness
  • Output voltage: 1.8 to 3.3 V with 3.3 V tolerance
  • Low-power consumption: 100-mW typical
  • Integrated short-to-battery and short-to-ground detection tests
  • AEC-Q100 qualified

The automotive-grade TW9992 analog video decoder is available in a 32-pin wettable flank QFN package. It costs $3 in 1,000-piece quantities.

Source: Intersil Corp.

Qseven Module with Quad-core Pentium Processor with 4K Resolution

congatec AG recently announced an addition to its Qseven family. The conga-QA4 module includes the new Intel Pentium and Celeron processors based on 14-nm technology and offers increased energy savings and computing power. The optimized Intel Gen8 graphics, with up to 16 graphics execution units (EUs) and 4K (3,840 × 2,160 pixels) resolution, create a high-quality visual experience.conga-QA4_congatec

The module comes in three different processor versions (Intel Braswell) for high scalability. They range from the entry-level, dual-core Intel Celeron N3050 with 1.6/2.08 GHz to the quad-core Intel Pentium N3700 with 1.6/2.4 GHz, each with a power consumption of 4 W for standard applications (Scenario Design Power, SDP).

With the new conga-QA4 module, you can upgrade Qseven applications to the latest processor technology quickly and easily. The Qseven module comes with up to 8-GB, dual-channel DDR3L memory and up to 64-GB eMMC 5.0 for mass storage. The enhanced integrated Intel Gen8 graphics supports DirectX 11.1, OpenGL 4.2, and OpenCL 1.2. The new hardware-accelerated video decoding of H.265/HEVC requires a 50% lower data rate compared to H.264/AVC, so you can stream 4K videos in real time.

You can use the conga-QA4 module for a variety of retail, digital signage, and medical applications, or whenever you need high-performance graphics, outstanding computing power, and passive cooling. With native USB 3.0 support, the conga-QA4 module provides fast data transmission despite low power draw. Six USB 2.0 ports are available, one of which is executed as USB 3.0 SuperSpeed.

Three PCI Express 2.0 lanes and two SATA 3.0 ports with up to 6 Gb/s allow fast and flexible system extensions. The Intel I211 Gigabit Ethernet Controller offers the best software compatibility, while I2C bus, LPC bus for easy integration of legacy I/O interfaces, and Intel High Definition Audio with an 8-channel sound card round off the feature set.

Source: cognatec

Electrical Engineering Crossword (Issue 299)

The answers to Circuit Cellar’s June 2015 electrical engineering crossword puzzle are now available. 299-Grid-(key)

Across

  1. CURRENT—Eddy
  2. LUMEN—A lux is one per square meter
  3. KILBY—Nobel prize for physics in 2000
  4. EXABIT—1,000,000,000,000,000,000 bits
  5. ARITY—Programming term for the number of arguments or operands a function or operator takes
  6. PION—Pi meson
  7. STATOHM—Five of these equals approximately 4.5 × 1012 ?
  8. LIN—Bus system for automotive networks
  9. PATCH—Supplemental software as a fix
  10. BITERROR—Incorrect reading of a bit [2 words]

Down

  1. XTAL—Crystal
  2. MINIMA—Lowest point in the domain of a function
  3. FLEMING—Electrical engineer (1849–1945) who designed the thermionic valve
  4. HERTZ—Cycles/second
  5. BAT—BATCH FILE
  6. TRIVALENT—A valence of 3
  7. ANECHOIC—Absent of sound
  8. FILTER—Blocks or allows to pass
  9. GND—Ground
  10. ACID—pH < 7

Electrical Engineering Crossword (Issue 298)

The answers to Circuit Cellar’s May 2015 electrical engineering crossword puzzle are now available.298-crossword-grid-(key)

Across

  1. ATTOSECOND—10-18 of a second
  2. SHIELDING—A barrier of conductive or magnetic matter
  3. HAPTIC—Relating to touch
  4. BEAMFORMING—Signal processing for sensor arrays
  5. SCRIPT—A sequence, instructions
  6. TRIMPOT—A small potentiometer used for making preset adjustments in a circuit
  7. LUX—Light intensity
  8. DEMAGNETIZE—Degauss
  9. XENON—Xe
  10. COAXIAL—Sharing the same axis
  11. DECIBEL—0.1 bel

Down

  1. CENTIMETER—0.3937 inches
  2. CATWHISKER—Flexible sharp wire that connects to a semiconductor crystal’s surface [two words]
  3. FEMTO—0.000000000000001
  4. SUBSONIC—Less than 15 Hz
  5. IMPULSE—An abrupt burst of signal energy
  6. ALTERNATOR—Mechanically driven generator of AC electricity
  7. HOMEBREW—DIY, homemade
  8. AMPHOUR—Current flow over time
  9. BAUD—200 bits per second = 200 what?

Electrical Engineering Crossword (Issue 297)

The answers to Circuit Cellar’s April 2015 electrical engineering crossword puzzle are now available.297-puzzle-(key)

Across

  1. RELAY—A switch actuated by another electrical signal
  2. OFFSET—A permanent deviation from the design center of any device or circuit
  3. DIP—A component for a PCB use that has pins arranged in two parallel rows
  4. DECIBEL—1/10th of a Bel
  5. ENCODE—Convert analog information to digital data
  6. DAMP—Suppress a resonance by absorbing stored energy through the application of mechanical or electrical friction
  7. DELIMIT—To define or set limits on the boundaries of something
  8. LOOP—Two electrically conductive paths carrying the same signal
  9. CHARGE—State of having a stored excess or deficiency of electrons, which imparts electrostatic polarity to a capacitor or object
  10. DECIMALS—10.1 mal equals 10 what?
  11. OVERSHOOT—The tendency for a rapidly increasing or decreasing electrical impulse to exceed momentarily its actual peak level

Down

  1. CENTIMETER—0.3937 inches
  2. COAXIAL—Sharing the same axis
  3. FIELD—A volume of space through which any radiated energy is distributed
  4. DETECTOR—A circuit that extracts the modulations from a carrier
  5. CELL—An electrochemical unit for producing DC electricity
  6. CARDIOID—Heart-shaped
  7. PATCH—Reroute a signal to a different circuit
  8. JOULE—An “erg” is a unit of work equal to 1–7 of these
  9. FRAME—A digital signal comprises a series of these

Electrical Engineering Crossword (Issue 296)

The answers to Circuit Cellar’s March 2015 electrical engineering crossword puzzle are now available. 296-grid-(key)Across

2. HUM—Field of 60 or 120 Hz magnetic or electrostatic energy
5. SWEEP—Scan of a range of frequencies
6. WIREWOUND—WW
13. POTENTIOMETER—Pot
14. NANO—Prefix that divides a unit by a billion
15. ISOTROPIC—Exhibiting the same physical properties in all directions
17. MICROMETER—One millionth of a meter
18. INCREMENT—To change in value by a discrete step
19. INTERFERENCE—RFI, EMI
20. MULTIMETER—Test instrument that can make several different measurements

Down

1. QUALITYCONTROL—QC (two words)
3. FLUX—A field of radiated energy
4. FERROMAGNETIC—Magnetizable substance based on iron
7. DIFFRACTION—Bending of energy waves as they move around or through an obstacle
8. JUNCTION—Any connection between two electrical conductors
9. CLIPPING—Slicing off of signal peaks
10. COMMON—Conductor shared by various circuits
11. SUBSONIC—Slower than the speed of sound
12. DECODE—Convert a digital signal back into an analog signal
16. CAPACITANCE—Measured in fractions of a farad

Electrical Engineering Crossword (Issue 295)

The answers to Circuit Cellar’s February 2015 electrical engineering crossword puzzle are now available.295puzzle

Across

2. COMMON—A connection or conductor that a number of circuits share
5. TRIODE—Comprises a cathode, plate, and control grid
6. SKINEFFECT—The tendency for electrons at high frequencies to travel along the surface of a conductor [two words]
7. IBM—Big Blue
9. PASCAL—Pa
10. SHEATH—Tube that protects a bundle of wires
15. AVOGADRO—6.0221415 × 1023 atoms/mole
17. CONDENSER—A capacitor
18. MEGA—M
19. QFACTOR—Measures the damping of resonator modes

Down

1. BIDIRECTIONAL—Figure-8
3. OSCILLATION—Self-sustaining generation of a continuous electrical signal
4. SELFBIAS—Cathode bias [two words]
8. MANCHESTER—In this code, common in telecommunications, each bit of data is represented by at least one voltage level transition.
11. WIREWOUND—WW
12. TANGENT—Straight line that touches a circuit a single point
13. MALE—Hot signal connector
14. FERROUS—Containing iron
16. OHMSLAW—R = V/I [two words]
17. CBAR—0.01 bar