mistake on leds

[Corvette Reefer]

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

[EMUreef]

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

what driver did you use?

[CableGuy]

what driver did you use?



Doesnt matter... with constant current drivers, you need to turn the DRIVER OFF, not the led's.

[EMUreef]

Doesnt matter... with constant current drivers, you need to turn the DRIVER OFF, not the led's.

maybe it matters to me?

[CableGuy]

Mean Well LPC-35-700W constant current driver (http://www.rapidled.com/servlet/the-3/driver-700ma-48v-drivers/Detail)

From his build thread.

[CableGuy]

I've not messed with leds yet but.... what does it matter? If anything, IF properly wired wouldnt it just blow the switch not the actual leds/driver??


Im not an electrical engineer but it has something to do with the "constant current" and how that circuitry is used. The driver needs to soft powered on.

I think when switched off it is pulling 0mA. Then when you switch it on, it sends more than the 700ma through the pipe line frying all of the LED's.

[EMUreef]

most switchs are rather simple , there really is no way to blow the switch as most of them dont have anything electrical. the switch just basically moves the current from off to on with a piece of metal.

Adam has it right, the drivers are a slow start up basically go from 0-700ma, with the switch its a one shot of 700 and blows the LED's.

[AChambers5]

So would it be fine to put the swithch between the drivers and the power source, or the power source and the plug outlet? From my understanding of what i have read here both should be fine, Just wanna make sure cause i am in the beginning of my own LED build.

[Sir Patrick]

Sorry to hear this happened to you little bro......

Leds can be replaced.

[EMUreef]

So would it be fine to put the swithch between the drivers and the power source, or the power source and the plug outlet? From my understanding of what i have read here both should be fine, Just wanna make sure cause i am in the beginning of my own LED build.

I could be wrong but yes you could do this

[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