LED help needed

[phat_levin]

hey guys i need some help! i have a vvt light and switch set up and switch works fine, only thing is the led's keep blowing.

the negative leg is connected to the vvt wire coming off the switch, and the positve leg is connected to a 510 ohm resistor and a 12V supply.

my theory is that the 12V that comes from the VVT wire wen vvt is off is too much for the led? only thing is i dont know how to fix this?

any help would b appreciated, i know i have asked about this before but this is still a problem!!!!

[Crampy]

Are you sure it's a 510ohm resistor? what are the colours of the bands on the resistor.
I run the very same setup, but have never had a problem.

[phat_levin]

the bands are green red black black and brown. the packet says 510. i didnt have a problem wen i had just the light, its only since iv added the switch in for the vvt that this has started happening......

wat does ur switch do? i have mine set up to have VVT running normally, on all the time, or off all the time...

[sergei]

What happens is that you get EMF from solenoid (probalby couple of hundreds volts) blowing your LED, what you need to do either connect so when you flick the switch to disconnect the vvt solenoid make sure the LED is disconnected as well (connect it before switch), or you could hook up a 1N4004 diode (or similar) in parallel to LED in such way so stripe on the diode will face +12V supply. LEDs are not designed to handle a few hundred volts in revesre.

[Vertigo]

ive got a switch for certain cosmetic lights which uses a direct 12v line, and i run an LED through it too, using an 800ohm resistor. never blown once, and still bright.

[Stealer Of Souls]

the bands are green red black black and brown. the packet says 510. i didnt have a problem wen i had just the light, its only since iv added the switch in for the vvt that this has started happening......
wat does ur switch do? i have mine set up to have VVT running normally, on all the time, or off all the time...

5
2
0
no more zeros
1% tolerance.
520 resistor. But unimportant...

0 black
1 brown
2 red
3 orange
4 yellow
5 green
6 blue
7 violet
8 grey
9 white
(could have grey and white around the wrong way...)

Fly back diode is the answer.
Or grab a 12V regulated supply IC.

[phat_levin]

thanks for the help guys. what is a fly back diode?

i will try putting a diode across the led and see what happens.....

[Crampy]

My switch was set up to lock the VVT on. With the switch off, it ran as normal and with it on, it just earthed out the VVT pin on the ECU, so locking VVT on continuously.

I have never had a problem with LEDs blowing either.

[Stealer Of Souls]

thanks for the help guys. what is a fly back diode?

i will try putting a diode across the led and see what happens.....

A technical term for the diode you're putting across the LED...

[Crampy]

Or flywheel diode.
It's to protect circuit components from the back EMF produced from switching inductive loads (eg. motors)

You sometimes need to put a resistor in series with the flywheel diode, to help dissipate the energy as heat, as you can also cook the flywheel diode with too much forward current.

Or something along those lines hehehe

[phat_levin]

well i wired it up today, without the resistor in series with the diode (only just read that) and it seems to still be working, so fingers crossed!!!

[Crampy]

Good as. The LEDs you got are probably quite sensitive to the switching.

That diode should help see you right from now on.

[ch4ng]

hey i know this is an old thread but anyways...the vvt wire youre talking about...is that the vvt wire on from the ecu?

[postfach]

viewtopic.php?t=9236&highlight=vvt+light

[MrOizo]

Digger!!!

Shit thats a awesome pic!!!

[Boosted_162]

Digger!!!

sh*t thats a awesome pic!!!

I thought the same thing!!