# Choosing the Right Resistor for Your Project

• onceinalifetim
In summary, the conversation is about buying resistors and capacitors for a project. The person is unsure about what wattage is needed for the resistors and what value to get for the capacitors. It is suggested to use standard values and to not use high voltages without proper supervision. There is also a circuit diagram being discussed and the need for accurate component values. Finally, there is a question about the availability of an 800nF capacitor. It is recommended to use a 820nF capacitor instead.
onceinalifetim
Hello

I need to buy 100k and 1k resistor.. but how do i know what watts do i need? 1 watt or 2 watts

hope help

and i need to buy 800nf capacitor..

what is the resistor being used for ?
you have told us nothing about the circuit its going into

800nF (0.8uF) isn't a standard value. [STRIKE]The closest you could get would be two 0.47uF (470nF) [/STRIKE] capacitors in parallel

EDIT
Actually a better choice ould be a 470nF and a 330nF = 800nF

I'm too tired LOL

Dave

From Ohm's law, you need 30 volts across a 1k resistor to generate 1W, so unless your project uses high voltages you won't need a higher wattage rating. Most likely a 1/4 watt or 1/2 watt would be enough. To get 1 watt through a 100k resistor, you would need a 300 volts. If you are asking this level of question, you probably shouldn't be building a project that uses high voltages, without proper supervision from somebody who knows what they are doing!

For the cap, 820nF is a standard value, and unless you need the "exact" value for some reason, that's likely to be near enough. (But if you got the 800nF from a circuit diagram, it does raise the question as why they specified that value)

AlephZero said:
...
For the cap, 820nF is a standard value, and unless you need the "exact" value for some reason, that's likely to be near enough...

Yeah I would have thought so but since it wasnt in the listed values of either of my 2 component suppliers, I didnt suggest it and hence went for the paralleled solution

Dave

that is my circuit for my project! similar design i mean

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davenn said:
Yeah I would have thought so but since it wasnt in the listed values of either of my 2 component suppliers, I didnt suggest it and hence went for the paralleled solution

I checked there were some suppliers on google before I posted it.
But I agree caps are usually only specified using the 10 - 15 - 22 - 33 - 47 - 68 series of values (or even just 10 - 22 - 47).

onceinalifetim said:
that is my circuit for my project! similar design i mean

So with a 5v supply, 1/4 watt resistors would be just fine everywhere.

L1 and C5 look like a tuned circuit, so the question is, how accurate does the frequency need to be? Since you don't have any way to fine-tune it, I would guess "not very", but that's just a guess.

What is the "sensor"? it is some gizmo and the data sheet says it has inductance and capacitance equivalent to L1 and C5, or are they "real" components?

You have R1 and R3 in series to make 1.56k, instead of just a single 1.5k resistor - does that mean you really do need accurate (and close tolerance) component values, or is it just that the person who drew the circuit had those two R values in their spares box but didn't have a 1.5K ... ?

It's hard to guess what the circuit does, just from the diagram.

thanks for the reply folks.. may i know is there 800nf capacitor in the market?

No, but you can buy 820nF cap.

i need help!

i need the capacitor value of 17nf and 151pf... is there in the market or is there any way to series or parallel it?

Last edited:

## 1. What factors should I consider when choosing a resistor for my project?

There are several factors to consider when choosing a resistor for your project. Some of the most important factors include the resistance value, power rating, tolerance, and temperature coefficient. The resistance value should be chosen based on the specific requirements of your circuit. The power rating should be high enough to handle the maximum power that will pass through the resistor. The tolerance indicates how close the actual resistance will be to the stated value. The temperature coefficient measures how much the resistance will change with temperature.

## 2. How do I determine the appropriate resistance value for my circuit?

The resistance value for your circuit should be determined based on the voltage and current requirements of your components. You can use Ohm's law (R = V/I) to calculate the resistance needed for a specific voltage and current. It is also important to consider the overall resistance of the circuit and how it will affect the performance of your components.

## 3. What is the difference between a fixed and variable resistor?

A fixed resistor has a set resistance value that cannot be changed, while a variable resistor allows for the resistance to be adjusted within a certain range. Fixed resistors are typically used for specific purposes, while variable resistors are often used for adjusting the voltage or current in a circuit.

## 4. Can I use multiple resistors in my circuit?

Yes, you can use multiple resistors in your circuit. In fact, it is often necessary to use a combination of resistors to achieve the desired resistance value. Resistors can be connected in series or parallel to modify the overall resistance in a circuit.

## 5. What is the best type of resistor to use for my project?

The best type of resistor to use for your project will depend on the specific requirements and constraints of your circuit. Some common types of resistors include carbon composition, metal film, and wirewound. Each type has its own advantages and disadvantages, so it is important to research and compare the options to determine the best fit for your project.

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