Circuit Design: Autodesk 123D Circuits #Autodesk #123D

123D Circuits is a revolutionary free tool for designing your electronic projects online. You can design in a familiar breadboard view and the app will guide you to make professional printed circuit boards with built in layout tools. When you’re done just click to have your boards professionally manufactured and shipped for free worldwide.

What’s also cool is how you can easily, simultaneously work on the same circuit with your friends. And at any point you can compile and emulate your Arduino code inside a live, editable circuit!

Guides: Grounding Principles

In a previous blog on supply bypassing, I cautioned that poor bypassing could increase distortion of an amplifier. A reader, Walter, asked an interesting question… where should you connect the ground of a bypass capacitor to avoid problems?

This raises questions regarding proper grounding techniques. Wow. Big topic, but I may be able provide some insight with a couple of simple examples.

Figure 1 shows inverting and non-inverting amplifier stages with unintended, parasitic resistance or inductance in the ground connections (highlighted in red). The nodes A, B and C are all intended to be ground. But if current flows in parasitic ground impedances, these nodes will not be at the same potential. It is these parasitic ground impedances that can allow distorted ground currents to contaminate signals.

 

Read more at Texas Instruments

Techniques for robust touch sensing design

Here’s an app note from Microchip describing the best design practices when developing capacitive touch applications in noisy environments:

This application note will begin by defining the problems caused by noise, and explain how that noise typically affects systems. Hardware guidelines will then be provided to help maximize the natural signal-to-noise ratio (SNR) of the application. Software techniques are then covered to describe some of the common methods used to filter a sensor’s signal to increase the SNR further, and then to make a decoding decision based on the behavior of the capacitive sensor.