Can PWM from a simple micro-controller duplicate complex sounds?

"Can PWM from a simple micro-controller duplicate complex sounds?" The answer is yes, with surprising results.

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Phase-Lock Loops ebooks

Phase-Lock Loops ebooks

 

PRINCIPLES OF PLL - INSTITUTE OF RADIO INGINEERING AND ELECTRONICS



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Phase-Lock Basics By William F. Egan



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Phase-Locked Loops : Design, Simulation, and Applications (Professional Engineering)

By Roland E. Best



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Digital Frequency Synthesis Demystified : DDS and Fractional-N PLLs (Demystified)

By Bar-Giora Goldberg

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PLL Performance, Simulation, and Design - 3rd Edition



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Phase-Locked Loop Circuit Design (Prentice Hall Advanced Reference Series)



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CMOS PLL Synthesizers: Analysis and Design (The International Series in Engineering and Computer Science



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Digital Pll Frequency Synthesizers: Theory and Design By Ulrich L. Rohde



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Digital Phase Lock Loops: Architectures and Applications

By Saleh R. Al-Araji, Zahir M. Hussain, Mahmoud A. Al-Qutayri,



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Phase-Locked Loops for Wireless Communications: Digital, Analog and Optical Implementations By Donald R. Stephens



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Free Electronics Design Software

Introduction to Free Electronics Design Software

If you are a student or a electronics hobbyist who does not need to have complicated electronics design software to help you in your design work, it is strongly recommended that you consider the following free electronics design software that can be downloaded. There are some software which allow you to use for 30 days or so before you decide to purchase them. However, if you can live with limited feature, you can get a free download without having to pay for a full feature software.

Among some of the free electronics design software that can be downloaded are free pcb software, circuit analysis software and electromagnetic planar structure analysis software.





EAGLE PCB Layout Editor Software

The EAGLE Layout Editor is a free PCB software (see the conditions) which is easy to use, yet powerful tool for designing printed circuit boards (PCBs). The name EAGLE stands for Easily Applicable Graphical Layout Editor. It has 3 main modules which consists of schematic editor, layout editor and autorouter.



Express PCB PCB Layout Editor Software

The ExpressPCB schematic and PCB design software is very quick to learn and completely free! Download a fully functional version here.



5Spice Analog Circuit Simulation Software

5Spice is a graphical user interface software that offers easy to use analog circuit simulation for the electronic circuit designer. 5Spice provides the analysis capabilities needed by experienced circuit designers while remaining easy to use. The focus is on analog circuit analysis and circuit design at the component level.



FiltersCAD Software For Designing Filters

FiltersCAD is a comprehensive PC based filter synthesis software package that provides active circuit synthesis.



Convert Your PC Into A Dual Trace Oscilloscope

Convert your PC into a dual-trace storage oscilloscope and spectrum analyzer. It uses your computer's sound card as analog-to-digital converter, presenting a real-time waveform or spectrum of the signal - which can be music, speech, or output from an electronic circuit.



Spice III simulator from Linear Technology

SwitcherCAD™ III is a high performance Spice III simulator, schematic capture and waveform viewer with enhancements and models for easing the simulation of switching regulators.



Sonnet Lite EM analysis Software

Sonnet Lite is a free feature-limited version of Sonnet's professional Sonnet Suite, which provides Electromagnetic analysis that is able to analyse predominantly planar high-frequency designs from 1 MHz through several THz. PCB trace crosstalk analysis, Microstrip matching networks and Microwave circuit discontinuities amongst others can also be analysed.



Multilayer Air Core Inductor Calculator

Calculate the number of turns, DC resistance and other inductor data based on the input data of the inductance, coil inner diameter, coil length and wire gauge.



Resistor Color Code Interpreter

Enter the color codes of the resistor and you will get its resistance. This calculator also shows the equivalent values of 2 resistors that are connected in parallel and in series.

 

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EMC Standards for appliances

EMC Standards for appliances

What is EMC ?

Ever wonder why you are requested to switch off your electronics devices when you are taking a flight? This is one of the typical case of EMC of which your electronics devices may interfere with the electronics system in the aircraft.

Electromagnetic compatibility is the capability of electrical and electronic systems, equipments, and devices to operate in their intended electromagnetic environmemnt within a defined margin of safety, and at design levels or performance, without suffering or causing unacceptable degradation as a result of electromagnetic interference.

As more electronics products e.g. handphones, radio ransmitters, solid state switching devices, motor drives devices are developed and push to the market, the increase of electromagnetic pollution is on the rise everyday. These devices caused emissions to the environment where it was used.

As a result of these emissions, they will affect other electronic equipment which is susceptable to these emissions. As more microprocessors are used to replace analog or mechanical means of a product, it become apparent that the issue of EMC cannot be ignored. Ignoring this will caused the product to suddenly malfunction or even caused damage to properties or lives.

Directive

In order to ensure that the equipments are designed to perform as close as possible in its environment, the European standards making body CENELEC(European Committee for Electrotechnical Standardization) has been mandated to produce standards for use with the European EMC Directive. For telecommunications equipment ETSI(European Telecommunications Standards Institute) is the mandated standards body.

There are 3 types of standards :

a) Product or product family standards, relating to a specific product or product family group. The product standards take precedence over the generic standards and are drafted to cover the particular range of product types. These standards should refer to the Basic Standards for test methods wherever possible. It wil consist of defining what tests to carry out, what levels or limits, and what operating conditions and performance criteria to apply. These are prepared by IEC, CENELEC or CISPR.

b) Generic Standards relating to a particular environment of use. At present these are for:

(i) Domestic, Commercial and Light Industry

(ii) Industrial environment

c) Basic Standards, to provide general information and relate to the disturbing phenomena and testing and measuring techniques. Basic standards do not contain limits or performance criteria. They serve as a reference for product standards and will not normally be listed in the Official Journal, but will be referred to in product or generic standards.

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What is CE Mark?

What is CE Mark?

Products that are exported to the EC and that are placed on the market for the final end user have to carry this mark. The manufacturer or his representative is required to issue a declaration of conformity which must be kept available to the enforcement authority for 10 years following the placing of the products in the market. He is required also to affixed the mark on the products, or its packaging, instructions or guarantee certificate.

The CE mark is as shown below and must be at least 5mm in height.

What it means to have CE Mark?

When the CE Mark is affixed, it means that the products conform to EMC(Electromagnetic Compatibility) Directive and other relevant Directives that are relevant to the products. Many electrical appliances also have to conform to Low Voltage Directive. Electrical toys will have to conform to Toy Safety Directive.

The EC declaration of conformity must include components like :

a) Description of the products.

b) A reference to the specifications under which conformity is declared.

The reference to the specifications does not necessarily mean that you have to test these specifications. Three scenarios are apparent.

i) The product intrinsically meets the requirements of the Directive and does not need testing. Most electronic products are not able to follow this option.

ii) Declaration is make on existing test results. If the products already conform to existing standards such as FCC for emissions and IEC 801 for immunity, then you may be confident that the product will meet the appropriate harmonized standards without further testing.

iii) Test fully to the harmonized standards or choose the technical file route. For complex and new products, this will be costly but is essential.

c) Signatory to bind the manufacturer or his representative.

d) where necessary, reference to the EC type examination certificate for radio transmitters.

Compliance with the CE Mark Directive

There are 2 routes for manufacturer to comply to the CE Mark Directive.

a) Self Certification

Most manufacturer will follow this route which is self certification to harmonized standards. Harmonized standards are those CENELEC or ETSI standards which are announced in the Official Journal of the European Communities (OJEC).

The advantage of certifying against standards is that there is no mandatory requirement for testing by an independent test house. The only requirement is that the manufacturer makes a declaration of conformity as mentioned above which references the standards against which compliance is claimed. The manufacturer have to make sure that he tests the product to assure himself that it does meet the requirements of the standards and this can be done in-house. In the long run, it is cheaper to have its own basic in-house equipments to test the product instead of sending it to an independent test house which is costly most of the time. By having these facilities, it will enable the manufacturer to design in the product to conform to the standards as most of the time, a lot of modification to the product needs to be done in order to conform to the standards.

b) The Technical Construction File

The second route is to generate a TCF(Technical Construction File) which will be held by the relevant authorites as soon as the product is placed on the market and for 10 years after the last item has been supplied. TCF should describe the apparatus, the procedures used to ensure conformity and a technical report from a competent body. It may or may not contain test data. The difference between this route and the first route is that the technical report or certificate is issued by a competent body.

This route is normally taken when existing standards cannot be applied or when testing is not practical because of the size of the product.

This route is also taken when manufacturer decides to apply the harmonized standards in part only, or when the product has been tested to standards that are believed to have met the essential requirements.

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Introduction To Bluetooth Technology

Introduction To Bluetooth Technology

Bluetooth technology is a radio frequency short range communications technology that was created with the intention of replacing wired cables that are used to connect various portable and fixed devices. The use of this technology will do away with the physical cables that connect devices. The key features are its low cost, low power and robustness in maintaining high level of security.

Bluetooth was made possible by the Bluetooth Special Interest Group(SIG) which was founded by Ericsson, IBM, Intel, Nokia and Toshiba in the year 1998. The objective was to develop an open specification for short range wireless connectivity. More than 1900 companies have since joined the SIG and the numbers are increasing day by day.

Specifications

The specifications provide developers the link layer and application layer definitions which are used to support both voice and data applications. The spectrum of frequency used is in the unlicensed ISM(Industrial, Scientific and Medical) band at 2.4 Ghz to 2.485 GHz using spread spectrum and frequency hopping. As this is a free band, there is no cost for the use of Bluetooth compared to cellular phones where one must subscribe to use the network of GSM or CDMA.

IEEE 802.15.1 standard is used in the development of Bluetooth enabled products. The versions used are Ver 1.2 with data rate of 1 Mbps and ver 2.0 with data rate of up to 3 Mbps. The range of operation depends on the device classes. They are:

Class 3 – 1 meter range with maximum permitted power set at 1mW.

Class 2 – 10 meters range with maximum permitted power set at 2.5mW.

Class 1 – 100 meters range with maximum permitted power set at 5mW.

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INTRODUCTION TO FMEA ON STRESS DERATING

INTRODUCTION TO FMEA ON STRESS DERATING

This article recommends the criteria of FMEA in the area of stress derating of electrical and electronics parts or components and indicate the maximum application stress values to consider during design of electronic circuits. Derating is increasing the ratio of the margin of safety between part design limits and the allowable applied stresses. Derating provides extra protection for part tolerances and decreases the part degradation rate and by this it increases the life expectancy of a part.

The margin of safety of a part to both the threshold and time dependent stresses are generally unknown. As such, parts should be derated to the maximum extent possible depending on the maximum environment of which the parts are subjected to. During derating, one must consider the manufacturer's parts environmental specifications and the operating conditions of the application and then apply the derating factors so as not to exceed the maximum allowable application stresses set forth in this document. Take note that this is a typical design recommendation and designer should use their own discretion when applying using this FMEA document for their references.

EXAMPLE OF FMEA DERATING CALCULATION

A carbon film resistor which is rated at 2 Watts at 20 °C, linearly derating to zero at 85 °C being used in a machine rated at 60 °C. Find whether the rating of this device is suitable to be used or otherwise.

Step 1: Calculate rated power at 60 °C

P(60 °C) = P(25 °C) X [(Tmax - Toperating)/(Tmax - Trating)]

= 2 X [(85-60)/(85-25)]

= 0.83 W

Step 2: Find out the recommended maximum allowable stress from the table below - limit the power to 0.50

Maximum P allowed at 60 °C = 0.50 X 0.83 W = 0.415 W

Step 3: From the schematic design, find out the maximum power applied to the resistor. For example if the value of the resistor is 100 ohm and the maximum current applied is 0.05 Ampere, the power consumed is (0.05X0.05) X 1,000 W = 0.25W.

Step 4: The maximum power consumed(0.25W) is less than the maximum allowable derated power(0.415 W) and therefore it is safe to use the rated resistor in this application.

The table below shows the common components that are used and the recommended allowable FMEA derating factor.

Type of components	Critical Stress	Maximum allowable Stress factor
a) Fixed resistors
i) Carbon	Power	0.50
ii) Film insulated	Power	0.50
iii) Wirewound power	Power	0.50
b) Variable resistors
i) Wirewound	Rated current	0.70
ii) Non wirewound	Rated current	0.70
iii) All types	Voltage	0.80
c) Thermistor	Power	0.50
d) Capacitors
i) Ceramic	Voltage	0.50
	Current AC/Ripple	0.70
	Surge	0.70
ii) Paper	Voltage	0.50
	Current AC/Ripple	0.70
	Surge	0.70
iii) Plastic	Voltage	0.50
	Current AC/Ripple	0.70
	Surge	0.70
iv) Tantalum, foil or film	Voltage	0.50
	Current AC/Ripple	0.70
	Surge	0.70
v) Air	Voltage	0.30
e) RFI Filters	Current(steady state)	0.75
	Voltage(steady state)	0.75
f) Transformer/chokes	Insulation Breakdown voltage	0.50
	Current	0.70
g) Diodes
i) Recifier circuit	Power	0.30
	Surge current	0.50
	Forward current	0.50
	Peak Inverse voltage	0.50
ii) Switching	Power	0.30
	Surge current	0.50
	Forward current	0.50
	Peak Inverse voltage	0.50
iii) SCR	Power	0.30
	Surge current	0.50
	Forward current	0.50
	Peak Inverse voltage	0.50
iv) General Purpose	Power	0.50
	Surge current	0.50
	Forward current	0.50
	Peak Inverse voltage	0.50
v) Zener	Power	0.50
	Forward current	0.50
vi) ALL types	Junction temperature	110 °C
h) Transistors
i) Power	Power	0.30
	Current	0.70
	Voltage	0.70
ii) Switching	Power	0.50
	Current	0.70
	Voltage	0.70
iii) General Purpose	Power	0.50
	Current	0.70
	Voltage	0.70
i) Voltage Regulators	Max. rated Input voltage	0.80
	Max. rated Output current	0.75
	Max. rated Power dissipation	0.60
j) Digital Integrated circuit	Output current	0.80
	Operating freq	0.75
k) Connectors	Contact current	0.60
	Working voltage	0.25

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