How do Your Wire a Resistor?

[SirTankBall]

so i want to ask a stupid ?, how do u wire a resistor the right way? i think the end with the red strip goes to the power source and the other end goes the LED. im a right? i got NTE resistors from my local radio stack  and i want to know how to wire them up right so i dont burn out my LEDs

 

[W-L]

Just now, SirTankBall said:

so i want to ask a stupid ?, how do u wire a resistor the right way? i think the end with the red strip goes to the power source and the other end goes the LED. im a right? i got NTE resistors from my local radio stack  and i want to know how to wire them up right so i dont burn out my LEDs

 

Resistors do not have polarity so it doesn't matter which way it faces. 

[SirTankBall]

oh really? from what i saw on google it looks like it does

[Billy_Mays]

I think it doesnt matter since I did some soldering at school and I had no idea what I was doing but it turned out good but I had my resistor and battery hookup stolen from it but it was good

[Billy_Mays]

Just now, SirTankBall said:

oh really? from what i saw on google it looks like it does

Try to quote people with the arrow on the bottom below the text

[Delicieuxz]

The coloured stripes classify the value of the resistor, not the orientation it gets installed in. Capacitors have positive and negative leads, but resistors don't and can be installed either way.

[W-L]

Just now, SirTankBall said:

oh really? from what i saw on google it looks like it does

Nope makes no difference. 

http://www.instructables.com/id/LEDs-for-Beginners/

[DudeWazap]

It doesn't matter which direction they go. I have worked with soldering resistors to boards before and as long as its the right resistor is all that matters.

[SirTankBall]

alright cool. thx guys  

[Unimportant]

On 13.8.2017 at 11:51 PM, SirTankBall said:

oh really? from what i saw on google it looks like it does

You're probably confused with the order of the colored bands that indicate the resistor value. Obviously there is only one correct orientation in which to read the colored bands. If you reverse it you will read a wrong resistance value. But the resistor itself can be installed both ways.

[mariushm]

It makes absolutely no difference which way you connect it..  

It also makes no difference if the resistor is before or after the led, but usually it's better to have it between the positive side of your power source and the positive side of the led.

 

It's not a good idea to rely on the color bands to figure out the resistor value, better to use a multimeter every time. There is a standard for color bands on resistors but there's also some variations for special purpose resistors (like flame proof, or resistors designed to behave like fuses)... such resistors can have additional bands or some bands on them can have colors that aren't usually used.

 

What you have there seems like plain 0.25w or 0.5w resistors

 

Remember the formulas .. Voltage = Current x Resistance  and from here you can derive Power = Current² x Resistance

So for example, let's say you have a 5v power supply and a LED with a forward voltage of 3.2v and you want to limit the current to 20mA (0.02A)

 

Voltage - LED forward voltage = Current x Resistance , so Resistance =  ( 5v - 3.2v ) / 0.02A = 1.8 / 0.02 = 90 .. so you'd probably go with a 100 ohm resistor.

If so, then the current going through the circuit would be  5v - 3.2v = current x 100 , so current = 1.8 / 100 = 18mA , and then the power dissipated in the resistor would be Power = 0.018² x 100 = 0.000324 x 100 = 0.0334 watts, which means you could use even a 0.125w rated resistor safely. (basically, if you go above around 75% of rated power, it's a good idea to choose the next size up, the higher power rating)

 

That's all you need to know about resistors and leds.

[jarmenti]

BBROYGBVGW   (any elec engineering students know the dirty rhyme for remembering this?). and you 100% use the color coding to know values of resistors, Its why its there!.. you arent gonna sit there measuring every resistor with a meter to find the value you need LOL (although double checking once you've found the one you need is in tolerance doesn't hurt w/ a meter). anyone that wants to know how to read them http://www.electronics-tutorials.ws/resistor/res_2.html

 

All that matters is your LED polarity... usually indicated by the length of the lead or the flat spot on the LED plastic. Positive lead is always longer.... or simply hook it up and if it doesnt work... reverse and try again!

 

[mariushm]

9 minutes ago, jarmenti said:

BBROYGBVGW   (any elec engineering students know the dirty rhyme for remembering this?). and you 100% use the color coding to know values of resistors, Its why its there!.. you arent gonna sit there measuring every resistor with a meter to find the value you need LOL (although double checking once you've found the one you need is in tolerance doesn't hurt w/ a meter). anyone that wants to know how to read them http://www.electronics-tutorials.ws/resistor/res_2.html

 

 

I graduated a technical university (i can officially say I'm an engineer) and we were never taught any mnemonics ... and they vary from language to language...

 

For example i still remember the one we learned for pi around 1992-1994 from older teachers who learned this in the communist times pi is 3.1415926535 so you count the digits of each word in a phrase and those are the decimals: "e usor a spune minunatul si utilul numar din manual" which translates into "it's easy to say [the] wonderful and useful number from [the] textbook" and then there were a couple more sentences that sounded something like "we're learning everyday new things to please our great leader ..."

Wouldn't help a non native person... and goes to show even i forgot the complete phrase.

 

Anyway, color bands can lose color due to UV rays if product is exposed to sunlight, the resistor can be undersized and the resistor can cook and become brown and color bands can deteriorate.. color bands are simply not reliable.

Also more and more people move to surface mount components where value is a 3 digit number and third digit is the number of zeroes.. ex 621 = 62 x 10 = 620.. or 102 is 10x 10^2 = 10x 100 =1000 ohm, 0R1 is 0.1 ohm or R22 is 0.22 ohm ... simple.

[jarmenti]

touche touche...    lol we just learned pi straight up by just remembering 3.1415926535...   after a while it just sticks in your head purely remembering the numbers. and theres a few mnemonics... bad booze rots our young guts but vodka goes well, or one about bad boys doing terrible things to young girls yadda yadda i'm not gonna spell it out  ... (my old man told me that one back when i had started electrical engineering technologist in college and I was like WTF!)

[jacques1mouton1]

Yup polarity doesn't matter. It can go either way.