How to wire led’ ?

CONSOLE_BUTCHER

CONSOLE_BUTCHER

CONSOLE_BUTCHER

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How do i wire an led’ so far i have 2 led’ and some resistors, i know i have to solder the resistor to the positive side, which is the longer prong on the led’.

What gauge wire do i need? I have some 22gauge and some 18gauge. Also, what connectors do i need to attatch the wire to?
 
To what you want to connect them?
Your PC?

22 gauge is more than enough for standard LEDs.
 
Assuming it is your standard 3-5mm, ~3 volt, LED then wiring gauge won't make much odds.

There are a lot of potential power sources inside a PC but ideally you'd want either 5V or 12V and an appropriate value resistor for the voltage and desired brightness.

Molex connectors have both 5V and 12V lines and one of the easiest to tap into in a PC but I'd recommend buying an old cable with a Molex connector on and adapting that rather than cutting or soldering to the PSU cables directly.
 
EsaT said:
To what you want to connect them?
Your PC?

22 gauge is more than enough for standard LEDs.
Click to expand...
Rroff said:
Assuming it is your standard 3-5mm, ~3 volt, LED then wiring gauge won't make much odds.
Click to expand...

Its a 3mm that im going to connect to a molex that is typically used with most led strips. The ideas always seem to dawn on me after making threads. :confused: Lol
 
CONSOLE_BUTCHER said:
Its a 3mm that im going to connect to a molex that is typically used with most led strips. The ideas always seem to dawn on me after making threads. :confused: Lol
Click to expand...
What colour that LED is/you got any part number for it?
Different colour LEDs have different forward voltage/voltage drop.
 
EsaT said:
What colour that LED is/you got any part number for it?
Different colour LEDs have different forward voltage/voltage drop.
Click to expand...

Its a green led, the ebay listing said it is 20ma, i ran it through a resistor detector after a google search and it said it was rated at 0.023/6w.I bought some resistors rated at .6w and 150ohm for the extra space.
 
So likely standard 2V forward voltage.
For connecting to 5V that would make 150 ohm series resistor if using one LED per resistor.
Iin case of two LEDs in serie that would make 50 ohm series resistor.
And two LEDs in parallel per resistor would make 75 ohms.

For 12V voltage correct series resistances would be 500 ohms, 400 ohms and 250 ohms for those same situations.

Do you want to have those LEDs next to each others or in different places inside case?
Though that 150 resistor in series with single LED would be pretty much simplest.
 
An easy way to set it up is to know the supply voltage, and apply a resistor in series with each LED. These little pairs can be placed anywhere so long as they have a direct connection to supply and ground.
 
People always make this mistake, unfortunately the Internet it absolutely soaked in this misconception.

When an LED says it's 20mA it means completely maxed out. Running it at 20ma will make it shine brightly and die fairly young. It will glow so bright it will hurt your eyes to look into it, like a torch. How young will depend on the LED. A cheap one will be begin dimming after a few tens of hours service. White LEDs are particularly bad at burning out early.

For indication 1 or 2mA is enough.
To light things up with 10mA is usually enough.
I wouldn't go beyond 15mA.

Modern LEDs are extremely efficient and will light with less than 1mA. For indication in electronics I have run them with 10K resistors from 5V giving them ~0.2mA for a 3V LED and they work fine.

The resistor is calculated by

supply voltage - forward voltage / current required

5V - 2V / 0.015 = 200 Ohm (A 220 Ohm is common).

Put the resistor on the negative of the LED. Either will work, but the negative side is common.

You have to use individual resistors to limit the current to multiple LEDs in parallel, you can't share them and parallel the LEDs as they are usually badly matched and some will take more current than others. If one LED presents even a fraction less resistance to the current then most of the current will flow through that LED and burn it out. the other won't light.

If however you want to use the 12V rail you can put up to 5 x 2V green LEDs in series and use a single resistor to limit the current. Put the resistor at the negative end.

total supply voltage - total forward drop / total current required.

So:
12V - 5x2V / 0.015*5
12V - 10V / 0.075 = 27 Ohms, a 22 Ohm resistor is common or 33 Ohm but you will be able to buy 27 Ohms.
 
PaulCa said:
You have to use individual resistors to limit the current to multiple LEDs in parallel, you can't share them and parallel the LEDs as they are usually badly matched and some will take more current than others. If one LED presents even a fraction less resistance to the current then most of the current will flow through that LED and burn it out. the other won't light.
Click to expand...

I've always gone 1 resistor per LED personally even instead of series configuration - I see people making that mistake with parallel diodes in general but as you said even the slightest difference in resistance can cause one to take all or most of the current load instead of it being balanced - back when I briefly studied electronics before dropping it for computing I watched someone's circuit do the magic smoke thing once the diodes had warmed up a bit enough for there to be a difference heh - after they were sure it would work from quick tests where thermal effects hadn't kicked in.
 
CONSOLE_BUTCHER said:
Which side is power delivered to ?
Click to expand...

Neither. The positive side just has a more positive voltage potential than the negative side. The current is constant across the whole circuit (defining a circuit as a path which consumes all voltage/potential). This is Kirkchoff's current law, https://isaacphysics.org/concepts/cp_kirchhoffs_laws . As to which direction current flows, classical electronics says + to -, but physics says - to +.

One reason to put the resistor on the "low side" (negative) after the load is that it will not affect a voltage drop before the load, if the supply is 5V the LED will see 5V on it's positive side. However putting the resistor before or after the LED will lower the current in the circuit by Ohm's law.

For a basic LED+Resistor circuit there is no difference putting it before or after.
 
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