Resistors Are Cool

Electronic engineers and manufacturers are realizing the increasing importance for "designing in" an adequate margin of safety to protect against high energy, short term current surges or voltage spikes. Likewise, protection also needs to be considered in the final circuit design where there exists a potential for more frequent, but less intense power surges.  Resistors are an important part of any electronic system.

One thing to look at is tolerance to actual resistance specification of resistors. If the manufacturer states a 5% tolerance to the ohm spec, it really needs to be at or below that number. Another thing to check is how much voltage it can handle. This should be listed in the spec sheet for each particular resistor. Depending on whether the design is for a high-power application like a power supply or something much lower, like a calculator, one needs to watch for that. Lead sizing should fit the design. For example, one should not buy a through-hole type when a surface mount design is preferable during the engineering phase. Also, temperature specifications should be looked at to ensure thermal breakdown does not become a problem during peak performance of the resistor. It needs to be able to handle rapid fluctuation in temperatures, as various devices can change temperature quickly in real world applications.

A resistor is a passive current limiting device. Current limiting in that they are used to slow or limit the amount of electrical current traveling through them just like a cyclist experiences when attempting to peddle full speed after encountering an increasingly strong headwind. In controlling the flow of current, the electrical potential (voltage) can also be managed. They are passive since no external power or other source is required for them to function properly.