Which connection for 2 pin LED's ?

[paulstung]

I've just bought some 5mm led's 1 for my res and a couple for my flow meter, but I'm a bit unsure of which pins on my motherboard ( MSI Z87 MPower )

So simple question, what pins can the pins be plugged into ?

 

[tinytomlogan]

I wouldnt plug them into your mobo at all tbh

 

[paulstung]

Oh bugger. Is there any way to connect them without having to buy a 2 pin hub, They are the Phobya 5mm to 2 pin ?

 

[remember300]

what voltage are they.

Might be worth coming off of a molex.

 

[paulstung]

There is no info on the packet, but from a quick search they're 3v max.

 

[tinytomlogan]

Might have to link us matey - this should have been considered before hand though lol

 

[remember300]

does it list the ma or wattage ?
and why did i not think linkies lol doh

 

[Remmy]

Aye, red cable (5V) off a molex through a resistor of about 100Ω to the anode, and black cable (gnd) from the molex to the cathode is your best bet. Stick the three of them in parallel each with their own resistor.

If you put them in series the resistor will probably get too hot. They're typically rated at 0.25W, but for a typical 20mA for each LED through the single 100Ω resistor, the heat produced would be P=(60mA)^2(100Ω) = 0.36W.

Edit: Just seen the new posts. 3V is typical for an LED, 100Ω will give you about 3V from the 5V molex assuming about 20mA, which is typical for most LEDs.

 

[paulstung]

It's these hers mate, but in white. http://www.specialtech.co.uk/spshop...LED-with-2-Pin-Connection--Red-pid-18510.html

I didn't buy them a mate gave me them because he, stood on my molex versions. I tried one on my back up rig the other day, connected to one of the JFP2 set of pins and it worked fine, I'm just unsure of long term use.

 

[remember300]

if they are 3V at 20ma ea then in a parallel config you would just have a 34 ohm requirement
V=IR
(5-3)=(20ma+20ma+20ma=60ma)*R
2/0.06=33.333....
or is that not how you would do it, id probs use a 2W resistor though.

 

[Remmy]

if they are 3V at 20ma ea then in a parallel config you would just have a 34 ohm requirement
V=IR
(5-3)=(20ma+20ma+20ma=60ma)*R
2/0.06=33.333....
or is that not how you would do it, id probs use a 2W resistor though.

I meant the three in parallel each with their own resistor, not just a single one for all three. If each has their own then they're 100Ω each, but if you use a single one for the three LEDs it's 33Ω.

I didn't bother calculating a different R for the parallel configuration, naively

Good point though, with the single 33Ω, then the heat produced would just be 0.12W, so that's absolutely fine with a standard resistor.

 

[remember300]

id just do it that way cos im lazy lol

i only mention a 2w res due to other factors like heat depending where he is running it plus any surges through the 5v line it may push up a little, trying to save work lol

 

[paulstung]

Thanks for the help guys but I think I'll make it easy and either buy molex versions, or a 2 pin board. Talking about resistors and ohms and what not makes my head hurt.