## Save Your Back by Using a High DeskMarch 14, 2008

Sitting actually puts a lot strain on your lower back. Over the years, working at a desk job can really injure your back so that you wonâ€™t be able to sit comfortably for extended periods of time anymore. After suffering such an injury myself, I found that the only way I could get back to work was to use a desk high enough to stand at while working. I also have a chair that is high enough so I can alternate sitting and standing. Even if you end up sitting most of the time as I do these days, it is still well worth it.

Most modular office furniture can be (more…)

## Schematic and PCB Design ProcessMarch 7, 2008

Question:
I would like to know how a circuit designer in OrCAD plans the schematic and layout for the digital, analog, power, low speed high speed portion of the PCBs?

Wow, this is a big but good question! For anyone considering undertaking a schematic capture and PCB layout for the first time, it can seem like a daunting task. A modern PCB serves not just as a means to interconnect components, but also as a mechanical structure, heat conductor, noise shield, and even as a circuit element, and must go through a complex automated manufacturing process to boot.

## 3-Phase CalculationsJanuary 5, 2008

Here is a Zoho Sheet to do various 3-Phase calculations. It can convert between line-to-line and line-to-neutral voltages, find current based on apparent power (KVA), and choose the required wire cross sectional area to meet the target voltage drop. When designing such a system, you must also meet all applicable laws and safety codes.

It is embedded below (more…)

## Wire Parameter CalculatorSeptember 20, 2007

This Javascript web calculator will calculate the resistance and ampacity for copper wire based on the gauge. Both metric (mm) and American Wire Gauge (AWG) are supported. Note: Ampacity is based on a curve fit to MIL-STD-975. To see the wire table that this calculator is based on as well as important information about wire insulation temperature ratings, click here.

Features:

• Results update as you type
• Several choices of units
• Units and other settings are saved between sessions
• Blog format allows user comments

Inputs:

 Wire Size AWG mm

Optional Inputs:

 Wire Temperature Deg.  C F Wire Length m cm ft inches Number of Wires in Bundle

Results (per each wire):

 Resistance Ohms Single Wire Ampacity Amps Wire Bundle Ampacity (per wire) Amps Copper Diameter mils mm AWG Copper Area mils^2 mm^2 Copper Weight kg g lbs oz

## Hex, Decimal, and Binary ConverterJune 29, 2007

This web calculator converts numbers between the hexadecimal (hex), decimal, and binary formats. The calculator was designed to allow easy conversion between any of these three formats. This task is very common for those working with digital hardware and software including microcontrollers, DSPâ€™s, FPGA, etc. (more...)

## Skin Effect CalculatorJune 18, 2007

Electrical current always flows in the path that results in the lowest expenditure of energy. At lower frequencies, current flows in a path that reduces I^2*R losses. This is the path of shortest distance and is fairly intuitive to think about.

At higher frequencies, things get a little strange. (more...)

## Four-Layer High-Speed PCB DesignMay 29, 2007

When minimum cost and high-speed are required, a four-layer board may be the answer. High-Speed PCB design generally requires controlled impedance traces and good power and ground planes in order to meet signal integrity and power integrity requirements. Four-Layer PCBs are essentially made of 2 two-layer hardboards â€śgluedâ€ť together with a pre-preg spacer in between them. The thickness of the pre-preg is not as well controlled as that of the hardboards. So, for good controlled impedance traces, it is recommended to use the layers separated by hardboard as signal and ground. The layers separated by pre-preg can be used as power and ground.

Thus, a recommended stack up for a high-speed four-layer board is; (more…)

## PCB Stack-Up Design And Impedance CalculatorMay 12, 2007

Review: A new PCB stack-up design and impedance calculator is available for download from Istvan Nagy (see link below). It is a full-featured Excel-based tool that helps plan the PCB stack-up so that controlled impedance traces can be effectively implemented. It covers both single-ended and differential traces and is based on the equation s from IPC-D-317A. It allows one to see the range of impedances that are possible for a given layer stack-up. It also has pre-distortion calculations to support high-speed compensation, a unit changer, and a materials library.

layerstack_planningoriginalipc.xls