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The article contains methods used to construct home-made PCBs. The article also contains discussion commercial methods of producing PCBs.

The design and construction of a unity-gain oscilloscope probe with low capacitance and good results up to 100 MHz is presented.

The design of a Coline M12SW oscilloscope probe for measuring AC voltages is described.

Issues concerning the techniques of measuring radio frequencies are discussed, with particular focus on instrumentation for reading millivolt measurements. Design projects for measuring instrumentation are presented, with details of performance and assembly techniques.

A description is presented of the design and construction of an impedance meter which can be used at a test frequency of 100kHz for inspecting the health of electrolytic capacitors. Circuit diagrams are included.

Alternatives to measuring circuit power are discussed, including a substitute for the electro-mechanical system in domestic power meters.

A tool for reading a capacitor's impedance at audio frequencies to several megahertz is described.

Issues are presented concerning the importance of accurately measuring power dissipation in miniaturized electronic circuits. The estimation of the temperature of components in the circuit is discussed.

Capacitors for switch-mode power supplies are evaluated.

Internet findings on variable-gain circuits are reported.

Information obtained from the internet on variable-gain circuits is presented, with focus on companders, Dolby B circuits and automatic gain and level controllers.

The significance of using subtle capacitor parameters to increase efficiency is shown with a regulator powered by battery. The behavior of a tandelta power supply is examined.

The phase-locked loop concept is explained and its use to modulate and demodulate AM,FM, FSK and BPSK signals is discussed.

General-purpose digital multimeters are acceptable for DC but most are poor at measuring AC signals. A new, high-performance millivoltmeter is easy to make and calibrate, while having a wide dynamic range and bandwidth. It can be implemented as a stand-alone meter or added to a DMM. Details of the design are included.

The benefits of transimpedance amplifiers compared with transconductance amplifiers when used for light measurements with a photodiode are discussed. Details of where to look on the Internet for advice on carrying out the conversion are included.

Transconductance amplifiers are used to drive rectifying diodes or optocouplers, and can provide an increased working bandwidth. Operational transconductance amplifiers (OTAs) were expected to become the dominant technology when first introduced in 1969. However the current lack of components may be due to the fact that many integrated circuits incorporating transconductance amplifiers are not classified as such.

A tan delta meter has been used to identify 31 capacitors with a tan delta in excess of 0.4. The design and development of a new prototype in-circuit capacitor tan delta test meter has previously been described, and various enhancements include the addition of a further INA118 instrument amplifier.

The Internet is a valuable resource when searching for electrical components. One particular component to be found online is Burr-Brown's versatile OPA660 integrated circuit which has a 700MHz bandwidth and low distortion. The eight-pin package combines a unity-gain, open-loop voltage buffer amplifier with a transconductance amplifier. Further benefits of the OPA are discussed.

Transconductance op-amps convert input voltage into an output current corresponding to the voltage difference at its differential input terminals, Applications in which transconductance op-amps have been used include all-pass filters, simulated inductors, instrumentation amplifiers and single-wire bidirectional communications.

Measurement of current depends on whether its amplitude and frequency is within the capabilities of a digital multimeter. Most multimeters have a restricted capability and the majority of resistors are inductive. Small clip on oscilloscope current probes are useful for most circuit measurements. Economical transformers are readily available for currents in excess of 100A, providing a voltage output suitable fro a 200mV DMM. A simple and reliable method to generate a consistent DC current uses a known fixed resistor linked between the adjustment pin and the output pin of an LM117/317 circuit.

Designing time continuous filters can be time consuming as a number of mathematical calculations are required. Standard filter design tables can provide shortcuts but awkward component values are often required. The Internet provides overviews of filter designs, although the author was unable to find a single, simple, time-continuous band-pass filter design shortcut.

The design of a meter used to assess the operational components of an aluminium electrolytic capacitor is described and illustrated. Impedance measurements at 100 kilohertz and circuitry diagrams are given.

The majority of non-electrolytic capacitor failures lead to a permanently short-circuited component. The traditional aluminium electrolytic capacitor is self-repairing, and has a built-in ageing mechanism. Failed aluminium electrolytic capacitors exhibit leakage of electrolyte, discolored insulating sleeve, electrolyte exhaustion and cathode-foil growth. There are problems related to measuring a capacitor in situ, but there are few in-circuit impedance testers which will measure a capacitor's impedance at high frequency.

Mathematical functions must often be performed on two or more voltages, and there are many dedicated multiplier/divider integrated circuits available. A linearized transconductance multiplier/divider integrated circuit based on the Gilbert Cell is the usual choice when calculation speed is crucial. These circuits can be configured for two signals and accuracy is good unless signal amplitude is too small. A second matched transistor can compensate for changes in reference current.

Electronics designers can avail of design data, data sheets, application notes and design guides which are available on the Internet. Designers who want more information on a component can visit the manufacturer's website and generate a data sheet by entering a part number. Specialist library search sites can be used when beginning a new design wherein the specifications of the parts to be used and the names of the manufacturers are unknown. Questlink.com, Info-quick.com and Icesoft are three library search sites which provide free information.

A cursory visit to the Internet by a writer has revealed several interesting developments in the computer and software industries. For example, Intel Corp is expected to launch its 'Katmai' processor for desktop systems early in 1999. The processor is expected to initially run at 500 MHz using a 100 MHz system bus. Microsoft Corp's Windows NT5 is expected to draw the scrutiny of the US Justice Dept, which is investigating the software company's allegedly anti-trust activities. Several firms and universities can give users tips on how to handle the year 2000 date transition problem.

The reflector bridge technique with a vector network analyzer to measure the 'S' parameters of a capacitor can be used to measure frequencies of more than 10MHz. These reflection bridge techniques can be used at up to a minimum of 40GHz using an HP8510 or 6GHz using an HP8753 with the application of appropriate jigs. The reflection bridge approach was first developed in the 1960s for characterizing high-frequency semiconductors.

Four programs downloaded from the Internet were used to evaluate year 2000 compatibility of a computer hardware. YMARK2000 from NSTLonline is a 35-kilobyte test program that assesses the performance of the basic input output system and the real time clock of computers when set to year 2000. One demonstration program from Computer Experts, namely 'setupmbt.exe' implements eight out of ten tests provided in the Millennium Bug Toolkit. The other programs evaluated were 'Test2000.exe' from The RighTime Co and 'killer.exe' from Computer Experts.

Capacitor failures may be detected and prevented by measuring the increase in both self heating and ambient temperature to give a direct relationship between the capacitor electron spin resonance and the capacitor through current. The best alternative for the implementing measurements is through a precision SMA 50-ohm load or termination having an appropriate phase meter. LCR meters utilizing this approach are capable of measuring at 30 megahertz but are priced exhorbitantly.

The properties of materials such as electrolytes, aluminum and tantalum used for making capacitors are explained to correlate their relevance to the function of capacitor devices. The materials have varying degrees of protective films for insulation which amount to the K value of 8 for aluminum, and 27.6 for tantalum. Furthermore, aluminum types are manufactured by impregnating it with liquid electrolyte while tantalum types with porous slugs are embedded with dry electrolyte.

Plastic film capacitors are categorized into two main applications depending on their electrode contents. Plastic film capacitors with metallized electrodes are applicable in traditional decoupling tasks while those with foil electrodes are functional in enhanced pulse-current handling applications. These type of capacitors are manufactured using flexible plastic dielectric films and base metal electrodes. The manufacturing of such film capacitors can be cost-effective compared to ceramic and other types of capacitors.

The innovative super-slim browser which can be downloaded at 1MB can fit a single floppy diskette. The 'Opera' Web browser or search software is a shareware program which can be obtained for only $35. The 'Opera' browser version 3.1 in German and English language is already available in the market. The browser in languages such as French, Portuguese, Spanish, Africans, Italian and Russian is still being developed.

Intel has provided fixes to classic Pentium and MMX processors which can allegedly overcome the hardware bug 'FOOF' that allows unnecessary codes to obstruct any computer command. To resume normal computer functions, the unit needs to be rebooted which can result to the lost of disk cluster. Intel plans to release the Pentium II processor but there are some concerns with regard to very minimal improvements over its processors.

An innovative dish assembly which utilizes multiple Inbs can be utilized in receiving satellite transmissions from various high-frequency satellites. The satellite dish allows viewing from more than one satellite simultaneously and switching between satellites immediately. The satellite dish assembly may use two different forms which include concentric-fed style dish and offset-fed dish structures.

Mica is used in capacitor manufacture because it is flexible, easily cut with a sharp knife and it is transparent at high temperatures. Its most useful property is that a mica capacitor's final value can be trimmed to 0.5pF for values less than 50pF. Mica capacitors have now been superceded by NPO/COG ceramic capacitors. It is important that only approved capacitors are used when they are connected to 230 volt mains electricity supply.

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A scrutiny of a variety of available low-cost, user-friendly, portable phase measurement meters has indicated that none of them can guarantee at least a 0.1-degree resolution at frequencies up to 100 kilohertz. A prototype of such a phase meter to guarantee 0.1-degree resolution at frequencies up to 100 kilohertz has been developed. Its conceptualization, development and step-by-step construction are discussed.

Hypertext mark up language (HTML) is the method for linking to relevant documents and is the basis of the present day World Wide Web. The Alta Vista keyword search engine comprises over 30 million pages and 10 billion words, with an index that is constantly rebuilt using a software robot. It is not always possible however, to ensure that a keyword search database is up to date. The Internet Sleuth offers a facility to search any six from more than 2000 databases, including Alta Vista.

Electronic component impedance can be measured using an HP 8753 vector network analyzer and the coaxial test jig HP16091A. Measurements taken using such a setup and on surface-mount miniature high-Q ceramic chip capacitors have yielded excellent repeatability, with measurements made from 1MHz to 3GHz. Among the factors to consider are reflection on transmission lines, measurement accuracy and accuracy enhancement.

A non-harmonic residue coming from figure-of-eight cable styles is examined using a 3 MHz wideband rf millivoltmeter and a double-beam oscilloscope. The distortions were found to have been caused by an rf noise coming from the transmission of the 'Talk Radio' broadcast station. The rf noise can be minimized by using coaxial cables with a conventional inductor output amplifier.

Coaxial cables used to link power amplifiers and loudspeakers to the power source perform better than other cables. The effects of cable characteristics on amplifier speaker systems are quantified using various experiments. Users of Naim and similar amplifiers lacking an output inductor should use the recommended cable and its length, regardless of the results. The ideal speaker cable must have zero resistance, inductance and impedance.

Coaxial construction facilitates consistent measurement of various cable characteristics, enables attainment of low capacitance cable at audio frequencies, and reduces loudspeaker cable impedance. Experiments on resonant and restrictive circuits measurements reveal that a very low resistance connection amplifier and loudspeaker cables are required for increasing loudspeaker damping. The cable measurement techniques and tests used for several cable parameters, such as impedance and attenuation with frequency, are described.

Speaker cables in hi-fi sound reproduction systems cause distortion of transients, and not of continuous sine waves. That is why conventional methods of distortion measurement are unable to confirm the presence of distortions, as they are based on a continuous sine wave. The modern method consists of two amplifiers configured back-to-back, separated by the cable to be tested and a load-sensitive voltage drive circuit. However, the audible distortions are caused not by the cable itself but by the mismatched impedance of the amplifier, cable, loudspeaker combination.

Electromagnetic interference filters (emis) are a group of capacitors or inductors designed to transfer the required signal and suppress the higher frequency unwanted energy but their actual workings are not well understood. Component value and energy losses are frequency dependent and load current is crucial for filter design. A novel Windows emi filter analysis program provides the necessary insertion loss and return loss while avoiding convergence techniques to prevent misconvergence. Mismatched impedance cause insertion loss in low-pass emi filters with the filter returning the emi back to its source.

The Internet is a global peer-to-peer network with around 30 million users. Anyone who has a microcomputer and a compatible modem may gain access via service providers. There are two types of connectivity, namely BBS 'dial-up' and SLIP/PPP 'dial-in' services. At present, there are several popular servers on line: Gopher, Veronica, Wais and Archie. Access to them may be gained via a browsing environment known as the World Wide Web.

A method for calculating power dissipation in capacitors for both sinewave and non-sinusoidal waveforms has been developed, eliminating trial and error in the selection of capacitors. Overstressed capacitors are at the root of most circuit failures, but in the time they take to fail completely, other components can be damaged, making diagnosis of the cause of the failure difficult. The procedure for calculating capacitor power dissipation is detailed.

Search engines can be used to find data on the Internet. The software package PartMiner is designed to find engineering parts on the worldwide communications network. It, and other tools like it, are used on the network Electronic Design Technology and News. Analogue circuit designs to achieve high-frequency performance are described and illustrated.

The latest developments appearing in many Internet reports include the sustained criticism of Microsoft Corp's Windows 98. Problems related to Windows 98 include frequently cited cases of upgrade installation problems and system crashes. The most recent warnings being given pertain to files that have been given sharing rights. Networked users of Windows 3.11, Windows 95 and Windows 98 will have shared files which may not be password protected and are therefore vulnerable to hacking.

Pentium Pro, Pentium II processors and Classic and MMX processors have been found to have bugs. The Dan-0411 floating point bug has caused calculation errors in the Pentium processors while the 'FOOF' bug could cause serious problems in Classic and MMX Pentiums because it might cause systems to crash. Internet service providers are worried that hackers might halt their systems using this bug. Microsoft has provided a patch for security problems in IE4.0 on it's web site.

There were mixed reactions to the final release of Internet Explorer 4 by Microsoft in October, with some reviewers recommending waiting for Windows98, which would incorporate a browser in its operating system. There is a wealth of component data on Internet, mostly in the form of .PDF files, which require the Adobe Acrobat 3.01 file, However the format is not used universally, and a file conversion utility may be a possible solution. Once required information is found it can be downloaded.