Now days nearly everything we own has some kind of wholesale electronics parts circuit board in it to make it smarter and save us time. As time goes on, every appliance in the kitchen and every tool in the garage will have a brain that either helps order your food, or adjusts the cut of your saw. Washing machines and dryers will all have automatic timers and switches so they can run during the peak solar power hours or when the wind is blowing to take advantage of cheap power. And your vacuum cleaner will know the difference between a kid’s toy and a wrinkled piece of paper because it will have recognition software and a camera. All of these components are put on circuit boards, some of them are active and some are passive components.

There Are Active Components and Passive Components

Lots of the parts inside the various smart appliances you own are considered passive in nature. That means they don’t do any switching, amplifying or other duties. More likely they are going to be resistors or capacitors with just one lead in and another lead out. The easiest way for the average person to know if a component is active or passive, is whether or not it needs an extra lead for power to make it run or operate.


Resistors are a very common passive component and they basically resist the current as it passes through. The resulting current will usually drop to a known value based on the amount of resistance vs the amount of current sent through. These are obvious components in the circuit board, cylinder shaped, with a wire coming in one end and out the other. The colored bands around the resistor are read with each color having a different value. And then the final band will designate the % of variance the resistor is allowed to have.


Capacitors, are also cylindrical shaped most of the time, but both wires will usually come out of the same end and the cylinder usually stands on its end as well. There are also capacitors that are shaped like small discs and again, the wires come out of one end and into the circuit board. Capacitors store a charge and then release it, that’s the simplest way to describe what they do. They can be used to clean up a signal and level out a current to keep it within certain parameters.

Active components are things like transistors that can be made to operate a function, like switching on and off a charge. When power is applied to one lead it can trip the switch and allow power to pass through, then switch off and back on again. There are several kinds of transistors and they do different things in the circuit. But what makes them active components is that they need a separate power source to operate and they don’t always do the same thing all the time, their duty changes depending on the instructions from the outside power source.

Learning about the various components, both passive and active, that are in circuit boards can be valuable. Some components wear out or become defective and can be recognized with the naked eye, such as capacitors. Resistors can burn out, but that’s usually a symptom of a larger problem elsewhere in the circuit. But by learning the basic components you’ll have a head start over anyone that has never looked under the hood of an electronic appliance.