mistake on leds

[Sir Patrick]

Just anyone out there making a led system hears a simple note for you

NEVER PUT A ON OFF SWITCH BETWEEN THE DRIVER AND LEDS

you will regreat spending $100 of dollars on leds to see them all dead

I know this guy....he needs his back yard dethatched......I will get a hold of him.

[evilc66]

The reason why you should never do this is because of the design of most common LED drivers. They use what is called "buck topology" (which is where Buckpucks get their name). This means that the driver steps the voltage down from the source voltage to what is required on the output. Without getting into the nitty gritty of how the driver works, the reason these drivers can be destructive in this situation is because of the inductor placed on the output to smooth and average the current output. Inductors are just coils of wire around a core (air, or in this case, iron). With power applied, a magnetic field is generated around the inductor.

Now, in this situation, the problem didn't come from removing the LEDs from the string, but connecting them again with the driver powered up. With the driver free-wheeling (no load), the magnetic field around the inductor is huge. Once a load is applied again, that load is dumped, and a huge voltage spike is applied to the LEDs connected, killing them.

There are some drivers that claim to implement safety mechanisms to prevent this, but I would just assume that the driver doesn't have this feature, regardless of the one you buy.

[PAZAZZ]

Oh yes!!! The Evil Voltage spike will bite like a deadly Rattle snake!!! Hehehehe

mA items are not forgiving thats for sure. Most Electronics are not forgiving unless there is a supresion diode in the circuit to absorb the instant spike.

[Corvette Reefer]

yeah chris let me know what he says... i need some leds asap

and yeah im never making this mistake again i cant believe that this happened.

[Mike]

How many did you kill??

[Corvette Reefer]

all 12 bulbs... 60 bucks worth