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Discussion Starter · #1 ·
I'm still in the proto stage (running a lash up Q5 oval/spot hybrid) but planning my first proper MCE build.
The plan was to put the electronics (home made buck cct) in the battery pack because I have more space here and probably use a flying lead and deans connectors for the battery.

However, given I just blew my first MCE within hours of getting it :madman: I am starting to wonder if it is sensible to leave the LED unprotected?
I didn't do anything stupid to the MCE, just probed it with a current limited PSU so either it was faulty (unlikely all dies would go though) or my PSU is dodgy (possibly slow to current limit) or I zapped the LED with static.

Anyone know how static sensitive these LEDs are?

Toby
 

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Randomhead
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ouch. I don't have much experience with high power leds, but I don't trust the current control mode of my bench power supplies that much. I usually increase the voltage doing the current control myself, and then work out the current setting.
 

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Did you check to make sure the die was wired correctly?
For instance thinking you have everything parallel and sending 2.8amps to a serial wired MC-E would blow it...
Although if you have a current limiting lab PSU I'm guessing your ok with the wiring.

Is it an emitter? Or on a star? On an emitter I only flicker my MC-E at low settings to make sure its working. on a star i'll run it for a bit with it AA'd to a heat sink.

But I did blow one emitter when I thought I had it AAd to a heatsink but it came loose and I didn't notice.

Other than that, they've all been pretty robust for me.
 

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Discussion Starter · #4 ·
it was definitely wired correctly (2S2P) as it worked fine for a short while. It was on a star but wasn't heatsinked properly. But then I only had it on briefly and my finger was on the back as a temperature sensor :)

I suspect my PSU. I think the current limit takes a short while to react to the load so it was giving a short duration volt spike whenever I turned it on.

But why I blew this one isn't my primary concern, when I get a replacement I can be more careful with the drive and heatsinking. But I am worried it will still be prone to ESD damage.

I could of course add ESD protection straight across the LED but I was wondering if anyone else had seen any problems.

Toby
 

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I have been very rough to my LEDs when it comes to ESD. Never wear any protection and wearing synthetic fleece jacket... :) they seem quite robust to me. Have used Luxeons, SSC P4 and cree XR-E, MC-E, XP-E and haven´t noticed any damage to any of them. (beside the ones I killed by overcurrent).

I would recommend you to use both voltage AND current limit when you turn it on. For example 2,7V/die and then rise it. You should then be safe it the current sensing is a little slow. Those leds burns out in milliseconds.
 

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Discussion Starter · #6 ·
Thanks for that, I think you have put my mind at rest. I might ask around at work though, I am sure someone will have a a few TVSs that I could "borrow" to be extra sure ;)

I will certainly be using the PSU as you suggest in the future, I can't afford to keep blowing these things!
 

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Which PSU are you guys using?
I was thinking of getting a Mastech HY3020E for this and other purposes, if the current sensing is too slow it doesn't seem that useful though.

As for ESD, honestly I've never damaged anything to my knowledge from ESD, that includes computer parts and other electronics projects.
 
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