how to know the resistor i need in electronics?

B

Brian T

New member
Consult "Electronic Now" mag. index. Use determines type, rating,composition, cost range, tolerence, reliability,
Generally, the cheapest one that wil fill the needs is chosen. Look to the senior engineer.
 
You've already been given good advice, but allow me to focus it: VARIABILITY, VALUE, POWER, ACCURACY. Do you need the resistor to be a fixed value or does it need to vary? If variable, you might need a potentiometer. If the variability itself must vary according to automatic conditions, you don't need a simple resistor ... you need a CIRCUIT itself there.

You should know the value needed at any rate. Since resistors are built over a wide range of power dissipation (since you ARE converting electron motion to molecular motion -- HEAT), you need to know the power rating of that resistor.

Finally, your application might require a fairly precise resistor value. Common resistors are fairly sloppy ... +/- 5%. That means your 100-ohm resistor might be anything from 95 to 105 ohms. Your application might not tolerate more than 1% variance from the designed value, or 0.1% ... and such accurate resistors are correspondingly expensive. GOOD LUCK!
 
Resistors have many uses and the value depends on the use and the circuit it is used in.

I can't supply any more info for this vague question. I suggest you study ohm's law and other electronics subjects.

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Resistors generally have 2 important values resistance(ohms) and power

if you are looking to power a LED or something really low current any standard resistor should be fine, but if your using it for anything that draws a fair amount of watts you need to use ohms law and power law to determine your resistor values
 
All the components not just the resistors are calculated based on the target objectives.
It is very application dependant.
Resistors are sometime used to set a threshold, a bias level, as attenuator, to limit the current…

Hope this properly answers your question

Guru
 
That's a bit hard to answer. Choice of resistor values depends on the application. Generally speaking, Ohm's law determines values, but not just on its own.
Resistors are used for many different functions.
 
That's a bit hard to answer. Choice of resistor values depends on the application. Generally speaking, Ohm's law determines values, but not just on its own.
Resistors are used for many different functions.
 
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