Image for post
Image for post

A September 2008 paper in the IEEE Sensors Journal, outlined sensor applications for early warning systems for bioterrorism. This effort was targeted at viruses with the ability of rapidly spreading in humans during a pandemic. Variants of such pathogens are difficult to detect, so a reliable detection strategy that could classify viruses from innocuous, harmless proteins is demonstrated in this article.

I am not an expert in this field, but I have to believe that this kind of detection process must have some use in our current COVID-19 pandemic. For all I know, maybe a similar technology is already being used or considered. …


Image for post
Image for post
(Image from Keysight)

I want to share some of my design experiences regarding the usefulness of the dB in engineering designs. It’s obvious that engineers work with numbers daily; some of these numbers may be quite large. In many of these cases we are able to use ratios of two numbers.

The base 10 logarithm begins out journey into what the dB is. It is actually a ratio of two power levels, and so is a quantity without any dimensions. The industry has named the units of dB as ‘Bel’, after Alexander Graham Bell, the telephone inventor. The decibel is commonly used in order to manage the large numbers; ‘deci’ is 1/10. …


Image for post
Image for post
(Image from Littelfuse)

So, you’ve just designed and tested your power supply and it works really well. It meets all of the required system needs and is ready to go. But wait! What about protection from that nasty environment out there in industry? Things like short circuit, overload, voltage transients from lightning, ESD, and other sources are waiting to destroy your new power design.

AC Mains

Let’s start with the AC mains input. This is usually 120 to 250VACrms. Figure 1.

Image for post
Image for post
Figure 1 Circuit protection of AC mains power supplies (Image from Reference 1)

A Fuse

Image for post
Image for post
(Image from Littelfuse)

Our first line of protection will be selecting the proper fuse. This is not as straightforward as you think.

Let’s start with the surrounding ambient temperature at the fuse where the temperature is usually higher in most instances, because it may be enclosed (like in a panel-mount fuse holder) or positioned closely to other warm/hot components, like resistors, transformers, etc. …

About

Steve Taranovich

BEEE NYU, MSEE Brooklyn Polytech, Eta Kappa Nu Honor Society, IEEE Educational Activities Chairman, Electronics Design Engineer 40 years, Tech writer 9 years

Get the Medium app

A button that says 'Download on the App Store', and if clicked it will lead you to the iOS App store
A button that says 'Get it on, Google Play', and if clicked it will lead you to the Google Play store