I'm trying to do a simple yet idiot thing, I wanted to connect a led to a cell phone charger that outputs 5v dc 0.4a but it does not give any light if the led is connected directly to the transformer, but if I connect to another regular cable with a junction box, it gives out light but overheats like crazy in seconds. Is this overkill? Also why is it only giving light if connected to another wire that is essentially just extending the connection?
>>51538865
Because the wire is a resistor
LED's aren't made for 5Vdc
learn 2 electrics pls
>>51538865
Put a 100ohm resistor in series with the LED.
l2electronics
>>51538967
Thanks for the replies guys, the led is white and should peak at 4v, didn't think it would still need a resistor for it.
>>51539010
>4 max
>let's use 5
nigga
>>51538865
Are you the 2.2 ohm resistor growled guy?
>>51538865
A typical red-LED is 1.9V for 10mA.
The resistor that have to be connected in serial is:
(5V - 1.9V)/10mA = 310Ohm
Get a standard 330Ohm resistor and it should work.
>>51539164
Yeah, I just wanted to do a quick goof for some people and don't have anything handy, was kind hoping it would hold up with some extra temperature and brighter.
Pic related, the led goes in the bottom to light up the acrylic stand. Can't go get a resistor today, but again thanks for the help guys.
>>51539492
Are you the guy from last time who was trying to set up some grow lights for the winter?
>>51539365
>>51539513
No, just some guy.
>>51539491
Also, the resistor should be able to dissipate this:
(U2/R)
(5V - 1,9V)2/330 = 29mW typical
triple this number to be safe: 100mW
This one is largely enough (167mW max):
https://www.sparkfun.com/products/8377
>>51539798
>U2/R
try U^2/R dude.
>>51540160
U2/R
wtf
