Hello everyone,
Most of the time I am more of a lurker on this site so it is a little odd to be posting.
Yesterday I decided to make a simple led light made up of 6 parallel rows each made up of a series of 3 (5mm) leds and an 80 ohm resistor to limit current. Connected to a 12v battery.
It was my intent to run the leds at about 40mA at the cost of lifespan but past tests have shown they should be fine at this current.
My weird problem is that one of the strings of leds is drawing far more current than it should and overheating, I cant work out why. I carefully checked and there are no shorts. All resistors (each 80ohm resistor is made up of 6 cheap 470 ohm resistors in parallel) have almost exactly the same resistance when read with an ohm meter. When powered the 3 leds drawing too much current have a voltage of about 10.4v and the other 5 stings have a voltage of about 9.9v.
Seeing as all the resistors are identical how is this happening?
Most of the time I am more of a lurker on this site so it is a little odd to be posting.
Yesterday I decided to make a simple led light made up of 6 parallel rows each made up of a series of 3 (5mm) leds and an 80 ohm resistor to limit current. Connected to a 12v battery.
It was my intent to run the leds at about 40mA at the cost of lifespan but past tests have shown they should be fine at this current.
My weird problem is that one of the strings of leds is drawing far more current than it should and overheating, I cant work out why. I carefully checked and there are no shorts. All resistors (each 80ohm resistor is made up of 6 cheap 470 ohm resistors in parallel) have almost exactly the same resistance when read with an ohm meter. When powered the 3 leds drawing too much current have a voltage of about 10.4v and the other 5 stings have a voltage of about 9.9v.
Seeing as all the resistors are identical how is this happening?