The Tech Blog

I was recently doing some background reading for a project and came across a cool concept called Gyrators. Sometimes also called synthetic inductors, they are circuit elements that emulate the behaviour of inductors using active components like opamps or transistors along with capacitors and resistors. The concept behind a gyrator is that it converts impedance, effectively transforming a capacitive or resistive load into an inductive one without needing a bulky coil.

A “real” inductor (coil of wire wound on a magnetic core) passes DC easily but its impedance rises with frequency. However, it can pick up stray magnetic fields, it has a winding resistance, and its self-capacitance can cause resonances in the audio range. By contrast, a gyrator-based inductor can exhibit very low resistance, virtually no self-capacitance, and isn’t sensitive to external magnetic fields.  By using gyrators, you can shrink the circuit footprint, reduce weight, and potentially cut costs. In many analog designs, such as active filters, parametric and graphic equalizers, and other low-frequency circuits, gyrators provide a way to precisely fine-tune frequency responses by simply changing resistor or capacitor values.

Design-wise, a common gyrator approach involve an op-amp configured with a few resistors and a capacitor to generate the same impedance that a real inductor would offer. The only drawback is, that these gyrator circuits expect one end of the inductor to be grounded. This means floating inductors can’t be replicated with gyrators. Also, gyrators generally aren’t suitable for high-frequency or power applications as they rely on the supply voltage of the op-amp. Works great in the audio range though.

There is a nice white paper by Rod Elliot on Active Filters Using Gyrators that shows the gyrator circuits in real life and its equivalent spice simulations. It’s a nice read if you want to explore this one further.

Fun fact: if you replace the capacitor in a gyrator with an actual inductor, the circuit behaves like a capacitor.

#BackToBasics #Electronics #Inductors #Capacitors #Filters #Audio

Anyone who’s ever designed a PCB knows the struggle of exporting files for manufacturing and assembly. Still, the question remains as to why there isn’t a proper file format to get PCBs to the board house and manufacture them end to end. Let’s discuss that today.

Today, the primary export options are Gerbers (in various versions) and ODB++. Most vendors support Gerbers as a standard but the issue is the number of files that get generated. Each layer gets its own file, on top of that you have to generate drill files, Pick n Place files, BOM files etc. If anyone has a non-automated workflow from CAD and it’s a pain to generate each time, double-check if it’s correct. ODB++ improves on this by bundling all necessary data into one zip file, yet its proprietary nature has its limitations.

Enter IPC-2581, which was released in 2004 and is an open-standard format designed to overcome these challenges. IPC-2581 consolidates everything from detailed design data and fabrication instructions to assembly information into one unified, XML-based file. It’s a single source of truth that aims to streamline communication across the entire supply chain, reducing the need for back-and-forth clarifications and lowering the risk of costly errors.

One of the standout features of IPC-2581 is that it handles fabrication and assembly. Not only does it provide all the necessary electrical and mechanical design details, but it also integrates manufacturing instructions such as solder paste application, pick-and-place coordinates, component footprints, and even inspection protocols. Additionally, it can incorporate the BOM, design tolerances, quality control benchmarks etc.

Although it hasn’t really taken off, it is currently in rev C of the standard with a lot of changes. I think part of the reason is most designers don’t know and some board houses don’t support them. To be honest, moving to this saves a designer & manufacturer so much trouble. The good news is that most CAD tools support this export as of today.

#BackToBasics #Electronics #PCBs