The best 4 transistors to keep in your parts kit

When your project needs a transistor there are tons of choices.  Which makes answering the question “Which transistor should I use or buy?” a daunting task.  Fear not, before wading through spec sheet after spec sheet consider of these 4 general purpose transistors.  Every electronics enginerd’s toolbox should have a few of each.

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9V Batteries Suck — And why you shouldn’t use them.

Smoke detectors beep when their backup battery dies, which always seems to occur in the middle of the night (at least for me.) These backup batteries are usually a small rectangular 9V. They have become popular choices for electronics projects. If you need your Arduino project to last longer than a day, this isn’t the battery you want to use.  Here’s why.

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AddOhms #8: LEDs and Current Limiting Resistors

The idea for AddOhms #8 has been around for quite some time.  I’m always trying to find ways to explain why current limiting resistors are necessary.  So while working in the shop one day, I decided to play with some LEDs and a bench-power supply.  Then I decided to record what happens.

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Unlike Speed Limits, Ohm’s Law isn’t a Suggestion

Ohm's Law Tutorial

Getting started with electronics always involves a discussion of Ohm’s Law. What is this mysterious sounding law and how can you use it when building electronic projects?  One the main uses for Ohm’s Law in your projects is to calculate the resistor value needed for a LED.  This article takes a look at what Ohm’s Law is and how to use it with LEDs.

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Electronics: Introduction to Breadboards

Soldering every circuit you build probably isn’t practical.  At some point you are probably going to want to use some type of temporary method to connect different components together.  One of the popular methods is using a breadboard.  This simple (and cool) looking device only needs a few instructions before you can begin

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AddOhms #6: Analog and Digital

It isn’t always clear what is meant by calling a device or a signal “analog” and “digital”.  This AddOhms tutorial explains the difference between analog and digital by using an analogy to clocks.  Old-school clocks with hands are a great example of “analog” while alarm clocks with digits as their display are an excellent example of “digital”.

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November 2013’s issue of Electronic Products features an article on the cover titled “Introduction to Polymer Capacitors.”  The author is, well, me. This article explains the differences between traditional MnO2-Tantalum and  Polymer-Tantalum capacitors.  Previously I explained these differences in the post on the fire hazard the Arduino GSM shield poses (due to improper derating).

You can find the Electronic Products article wherever magazines are sold or here:  Introduction to Polymer Capacitors.  Check below for links to high-resolution pictures.


Appearance:Introduction to Polymer Capacitors
Outlet:Electronic Products

Understand the difference between DC and AC

The fifth episode of AddOhms tackled the difference between AC and DC.  One of the things I wanted to stress in this tutorial is that even though the acronyms stand for “current”, they get used to describe voltages as well.  Which, after a video on the difference between voltage and current, seemed like something that needed to be stated.

No behind the scenes for this one, just the finished video.

Voltage Regulator Tutorial and Basics

Voltage Regulator Tutorial

Regulator Types

Fundamentally there are two types of voltage regulators:  linear and switching.  The names come from how they operate and how they achieve voltage regulation.  Linear regulators tend to be a little cheaper to implement, but they aren’t as efficient as their more complex switching variants.

There are also some “cheap and dirty” methods that some designs use.  Below is a brief description and example of each.

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Tutorial that goes over the basics of different regulators types

Voltage Regulator Tutorial

Digital ICs like microcontrollers, memory, and shift registers need a stable voltage source to make sure they work as expected.  Most circuits are designed with a voltage regulator to accomplish this stability.  In theory voltage regulators will vary their output to stay at a set voltage, regardless of how much current the load is drawing.  As a load draws a little bit more current, the supply voltage will begin to sag.  Conversely when the load is reduced the voltage may rise a little bit.  Regulators work to eliminate, well minimize, this change.

Full Tutorial:  Voltage Regulator Basics