LED's and resistors

[SmokinScott]

Do LED's and resisters have a positive and negative, or does it not matter which way you wire them?

 

[kinabaloo]

Do LED's and resisters have a positive and negative, or does it not matter which way you wire them?

The LED needs to be connected the right way around, with the positive lead facing the positive side of the battery and the negative facing the negative side of the battery.

The longer lead of the LED is the positive one.

100 ohms is the minimum resistor value; between 100 and 330 ohms (1/4w) will be fine for a 3.7v supply. LEDs ideal requirements vary according to supply voltage and their own 'forwad drop' voltage, but 100 ohms will be ok

As long as the resistor is in series with the LED, the LED should survive if you get it the wrong way around (but it will not light).

 

[SmokinScott]

Thanks Kinabaloo.

And the resistor, does it have a polarity?

A 100 ohm resistor goes brown black brown gold - gold would be the last band, (indicating tolerance), and be the negative pole, correct?

 

[cddz]

Thanks Kinabaloo.

And the resistor, does it have a polarity?

A 100 ohm resistor goes brown black brown gold - gold would be the last band, (indicating tolerance), and be the negative pole, correct?

No, the resistor has no polarity.

 

[kinabaloo]

No, the resistor has no polarity.

That's right.

And the colors you mentioned. brown, black, brown and then another color (accuracy band).

 

[Vapster]

If im running a 5v setup and the LED i have runs int the 3.2? to 3.6v range can i use 2 in series?

 

[Richie G]

That's right.

And the colors you mentioned. brown, black, brown and then another color (accuracy band).

>

FWIW, When learning Ohm's Law, regarding band values we were taught a rhyme to remember the color code.

Bad boys rape our young girls but violet gives willingly. Or...

Black, brown, red, orange, yellow, green, blue, violet, gray and white. (gold and silver don't fit the mnemonic -- multipliers of .1 and .01)

Of course, it's easier to just use an ohm meter. =)

 

[Vapster]

>

FWIW, When learning Ohm's Law, regarding band values we were taught a rhyme to remember the color code.

Bad boys rape our young girls but violet gives willingly. Or...

Black, brown, red, orange, yellow, green, blue, violet, gray and white. (gold and silver don't fit the mnemonic -- multipliers of .1 and .01)

Of course, it's easier to just use an ohm meter. =)

that too easy, We use that in the TV industry for coax

 

[zachari]

Make your life simple: An LED with built in resistor. I got one for 5v, works perfectly with 3.7v. One less component to design around. Frys have them in a few colors, comes with LED housing as a bonus (which I used, looks nicer).