Bench Talk

Circuit design incorporates elements that are often repeated across many different circuits. Learning these patterns can enrich your own designs and inform how you see others schematics.

It’s a great time to be an electronics engineer and an even better time to be a weekend warrior tinkerer. The line between these two worlds is rapidly evaporating as the tools that enable circuit design plummet in cost and skyrocket in capability. The most important thing that a product can do for us is to streamline our workflow while still delivering high quality results.

We built a smart mailbox, as related in an article, that had an ambient light sensor to detect when the mailbox door was opened. In that project we used a Vishay ambient light sensor (Mouser Part #782-TEPT4400) that acts very much like an NPN transistor, in fact the part is also referred to as a phototransistor. The difference being (when compared to a normal bipolar junction transistor) that instead of needing a base lead to setup the bias voltage, photons provide energy at the base-collector junction to turn the transistor on, thus allowing current flow from collector-to-emitter.

When you are just starting off in electronics, there are many design pitfalls that can lead to hours of frustrating troubleshooting. I highlighted the importance of troubleshooting in this earlier blog post regarding my work on the automated energy harvester. Many times these faults are fixed with a very simple tweak to the circuit design or component selection. One of the most basic of the faults is the infamous “floating pin” or “floating input” that can affect the I/O pins of digital integrated circuits.