KB6NU's Ham Radio Blog

KB6NU's Ham Radio Blog

Circuit Simulation

Interesting stuff from the trade magazines: circuit simulation, linearity, circulators and isolators

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EETimes10 Circuit Design Simulation Apps for Pros & DIYers. Whether you’re a professional printed circuit board designer or do-it-yourselfer, you know that testing your circuit board design is a must. Testing can save you money and time avoiding faulty PCB fabrication because it gives you a chance to fix what doesn’t work before the board is made.

It’s best to test your design out virtually. In other words, make a digital (virtual) prototype of your board and simulate (model) how it will behave in the real world. Here are some popular tools to do virtual testing. These software packages cost money but can save you costly mistakes.

Underlining the Meaning of Linearity. Linearity in an RF/microwave component or system is fairly easy to understand in concept: It refers to the ability of a component or system to provide an output signal that is directly proportional to an input signal. As a result, the relationship of the signal input to the signal output as a function of frequency is a straight line.

Achieving good linearity, on the other hand, is not quite so simple, even though it is crucial to preserving key pulse characteristics in a radar and modulation quality in a communications system. Whether it is a frequency mixer, an amplifier, or a complete system, many barriers to linearity must be overcome, often at the expense of some other performance parameter.

A Primer on Circulators and Isolators. Circulators and isolators are three-port passive electronic devices that help direct the flow of microwave signals in RF equipment and systems [including repeaters…Dan]. A port is defined as a connection point for either an input signal, output signal, or termination.

From my Twitter feed: EveryCircuit, WebSDRs, small transistors

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tlrosstech's avatar EveryCircuit fb.me/8is0QTbev

StrangeBeacons's avatar Strange Beacons @StrangeBeacons
Links to a Large Collection of Online WebSDR Radios: websdr.org #SoftwareDefinedRadio #shortwave pic.twitter.com/7kR95VWbKb

alinaselyukh's avatar “At some point in the near future, we’ll be building transistors out of just a handful of atoms… The gig is up.” twitter.com/npralltech/sta…
After Moore’s Law: Predicting The Future Beyond Silicon Chips n.pr/1rXxJg9

Mouser, NI offer free design/simulation/layout tool

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multisim-blueNational Instruments and Mouser have teamed up to offer an integrated design tool called MultiSIM Blue. Here’s what the Web page has to say:

With MultiSIM BLUE, the entire tool chain is fully integrated. Easily scheme, simulate, PCB layout, BOM and purchase all in one integrated tool. Discover an easy-to-use, seamless environment for the functional simulation of linear circuits using the Berkeley SPICE engine and over 100,000 components from the industry’s leading manufacturers – built-in from the start. Plus, parts will be frequently added to your Mouser parts database with the newest authorized components from Mouser.

System Requirements for MultiSIM BLUE

  • Windows Operating System
  • Pentium 4/M class microprocessor or equivalent
  • 512 MB of memory (256 MB minimum)
  • 2 GB of free hard disk space
  • Open GL capable 3D graphics card recommended (SVGA resolution video adapter with 800 × 600 video resolution minimum, 1024 × 768 or higher preferred)

Supported Operating System Requirements

  • Windows XP (32-bit)
  • Windows Vista (32-bit & 64-bit)
  • Windows 7 (32-bit & 64-bit)
  • Windows Server 2003 R2 (32-bit)
  • Windows Server 2008 R2 (64-bit)
  • Windows 8 (32-bit & 64-bit)
  • Windows 8.1 (32-bit & 64-bit)

I haven’t tried it yet, but it looks like an interesting piece of software, and you can’t beat the price–it’s free! I’m a little surprised that it only runs on Windows as NI really got started in the software biz with LabView for the Mac. That shouldn’t be a big deal for hams, though, as most of us have Windows machines in our shacks.

From the trade magazines: satellite tracking, online circuit design, open-source test board

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More cool stuff from the electronics engineering trade magazines….Dan

LEO satellite tracking in your backyard. Learn how one guy built his own satellite tracking system in his backyard.

The rise of the online circuit-design collective. Though still in the infancy stage, design and simulation tools that run entirely in the browser are pushing their way onto the EDA landscape. The ultimate goal is that they become essential players within the realm of professional design.

Test and measurement  turns to open source, Kickstarter. The field of test and measurement is set to benefit from open-source software applications if a Kickstarter fundraising project is successful. The Red Pitaya is a credit card-sized, reconfigurable measurement board with 60MHz of input bandwidth and an onboard Xilinx Zinq FPGA to perform signal processing.

From the trade magazines: spectrum sharing, active filters, real capacitors

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Passive components aren’t really so passive (Part 1): Capacitors. Transistors and ICs are considered active components because they change signals using energy from the power supply. Capacitors, resistors, inductors, connectors, and even the printed-circuit board (PCB) are called passive because they don’t seem to consume power. But these apparently passive components can, and do, change the signal in unexpected ways because they all contain parasitic portions. So, many supposedly passive components, like the capacitor shown below, aren’t so passive.

The model above shows that a capacitor adds more than just capacitance when you use it in a circuit.

Peaceful coexistence on the radio spectrum. How two engineers (shown at right) tried to get the military to share some spectrum with their small company.

Signal-chain basics #43: Active filters. While low-frequency filters can be designed with inductors and capacitors, they often require physically large and often expensive inductors. This is where active filters, which combine an operational amplifier (op amp) with some resistors and capacitors, become attractive. Active filters can provide an LCR-like performance at low frequencies

From the trade magazines – 092612

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Three more articles from recent editions of the electronics trade magazines.

HeathkitHeathkit: A right-time, right-place business. Heathkit was a popular electronics company for decades before its demise earlier this year. Former employees Lou Frenzel and Chas Gilmore share some memories and discuss the factors that led to its closing. Lou Frenzel is W5LEF.

In the article, he notes how he was instrumental in developing the Heath/Zenith line of computer kits. At that time, I was a fledgling test engineer working for Memorex (remember them?) making the 8-in. floppy drives that were an option for those computers.

Real-world testing of wi-fi hotspots. This article talks about both the RF testing and data communications testing needed to ensure a good wi-fi hotspot.

How to simulate cable in SPICE. This article covers the two main loss effects related to cables (the skin effect and dielectric losses) and presents a simple cable modeling method for use in standard SPICE simulators.