Building New Panels - Sharing the Process

[rives]

Are you trying to make a TVS by doing that? I ask because after many years of doing electronics work I've not seen two Zeners installed in opposing orientations.

After a fashion. I found this circuit after I fragged a string of LEDs when I had to take the heatsink assembly back out for some further machining and somewhere along the way encountered a spike that they didn't care for. While a zener works well in the conventional orientation if the driver and associated wiring is in place, I wanted some protection for either power connection when the driver and the LED module were separated.

Surface mount on that package makes sense. I'm from the axial lead era! So no, Rrog, that package would not work well for your application. Axial leads as in the other link would be easier to deal with.

 

[rrog]

Rives- You're simply saying I should use these Zeners: http://www.digikey.com/product-detail/en/1N4756A-TR/1N4756AVSCT-ND/3104326

 

[rives]

Yes.

 

[rrog]

Thank You!!

I'll say again, this heat sink is a monster. What a pleasure to work with. Thanks again for the recommendation, Rives.

Also- LOVING the Black Diamond head light!!!

 

[xmobotx]

i wore out a cap w/ LEDs for a 'head-light' ~defo handy ~i bet i could fix it now

sure like to see that heatsink

 

[rrog]

Yes, yes. So about photos, we can upload them to a gallery here on IC? I didn't know they had that kinda storage capacity here. I wonder if it will work through my proxy server. I was previously unable to open a Driver calculator, and if I try to open an embedded video, my browser will close. Blah blah.

Anyway, I'd love to get some pics of this up.

 

[rives]

I don't know about the particulars of your setup, but yes, you can put pictures up here. If you go to the page where you can get visitor messages (not pm's), on the right is the tab for albums. If you go into there, you should be able to upload some pictures and then link them into your posts.

 

[rives]

Another thought on the pictures, Rrog - I don't know if you are aware of it, but cellphone pictures need to have the accompanying data file stripped to remove the gps information that the little bastards include.

 

[hempfield]

Actually the ICMAG server remove any EXIF data from the image after the upload and re-size the image if is necessary. Only one sensitive information remains unchanged : name of the image, which in case of the phone pics, it will show the date and time when the picture was taken. This could be easily modified right after the upload, by renaming the picture.

 

[luvdemshrooms]

After a fashion. I found this circuit after I fragged a string of LEDs when I had to take the heatsink assembly back out for some further machining and somewhere along the way encountered a spike that they didn't care for. While a zener works well in the conventional orientation if the driver and associated wiring is in place, I wanted some protection for either power connection when the driver and the LED module were separated.

I asked my EE about your method of using Zeners as a TVS.

He suggests you use a bi-directional TVS.

I'm not an EE and he lost me while explaining the "why's and how's", but he's a very clever man.

 

[rives]

Actually the ICMAG server remove any EXIF data from the image after the upload and re-size the image if is necessary.

I recall reading this, but I also recall seeing a post where someone warned a poster that the GPS co-ordinates were still present on their picture. Relatively new feature, maybe?

I asked my EE about your method of using Zeners as a TVS.

He suggests you use a bi-directional TVS.

I'm not an EE and he lost me while explaining the "why's and how's", but he's a very clever man.

Good information, thanks. I was concerned that the zeners might not be as fast as a TVS, but I had them in hand at the time and have had no further problems. I didn't go out of my way to test them, however! I believe that it is a pretty common circuit for AC over-voltage protection. Google "back-to-back zeners".

 

[luvdemshrooms]

Well, whether it's a TVS, back to back zeners or a dual zener... I wish I had had one installed when I smoked 20 XML's in one shot a few weeks ago. Pretty much the same way you did.

Ouch!

Of course he then asked me why I didn't have a fuse inline with the LED's. (they do now)

He also steered me away from zeners in parallel with the LED's. His logic being...

if your driver/power supply has "crapped itself" (as he put it) would you rather have the string go dark if a LED fails or suffer a cascading failure as the zeners keep the string closed?

He's a thinker.

 

[rives]

Embarrassing as hell, isn't it? Those were the first chips that I've smoked from ESD in 30 some-odd years of working with them. I even had the power leads shorted together with a wire nut, but somewhere along the line I must have tugged on the wires, the nut fell off, and the wires came apart and came into contact with something that I wish they hadn't. Expensive lesson, and time consuming because I had mounted the LEDs to the stars, then epoxied the stars to the heat sink. It took some careful work with a hammer and chisel to get them back off.

 

[rrog]

Oh man... OK so Rives quickie tip #207: When farting around with the LED strings, twist the hot and neutral leads together to prevent ESD. And make sure your nuts are tight...

 

[luvdemshrooms]

Embarrassing as hell, isn't it?

Not quite the word I'd have chosen. I stared at them for a while, hoping that if I stared long enough that things would "get better". They didn't. In my case it happened when I disconnected a line so I could hook up my multimeter to read how many amps I was passing through the string.

Those were the first chips that I've smoked from ESD in 30 some-odd years of working with them.

It's almost worse when that happens. It's been a long time for me as well. I got careless.

Expensive lesson, and time consuming because I had mounted the LEDs to the stars, then epoxied the stars to the heat sink. It took some careful work with a hammer and chisel to get them back off.

LOL. That's why I use screws. Well... that and epoxy doesn't transfer the heat as well.

 

[rives]

Yeah, it didn't matter how many times I checked them, they were still dead.

I've been using screws ever since. I hadn't really planned on the LEDs being an item that needed servicing.....

 

[rrog]

I'm re-thinking my LED layout. I have strings of 10. 25 XM-L WW T3 and 25 XM-L NW T5. I can mix these per my asking that earlier, but I just wanted to double check.

My 50 LEDs are 5 rows of 10 on that beautiful sink. Alternating WW / NW. No biggie.

I had initially thought to string these by color, with only 1 string mixed WW/NW. Now I'm thinking to have the least running around f wire I should string these geographically on the sink. One sink per quadrant with the fifth being a solid string of WW that is shut off during veg. Those 10 LEDs are pretty effectively spread out across all 4 quads and I would fill in around them. This also means 5 smaller holes through the sink (I choke at this thought) for the drivers rather than one big one.

That's all a preamble for wanting to confirm my ability to mix these LEDs on a string.

 

[xmobotx]

hi rrog

the problem i experienced seems to be more due to the defective diode than mixing ratings

since you are not actually mixing ratings {warm/neutral still 10w} i would say as long as your diodes all test OK {light when tested <pref the diode setting on a multimeter} you should have no problems mixing w and n

 

[rrog]

Thank you!

 

[xmobotx]

honestly i dont think there should be problems from mixing ratings as long as the driver is within the upper spec of the lower rated diode and the lower spec of higher rated diode

been going over that 'event' for a while now and mostly i think the malfunctioning diode {which tested faulty} combined w/ not having the heatsink positioned properly so that the string was heating up beyond spec

so you know; make sure your heatsink is functional before firing it up and considering you are running well within ratings, using all tested 'good' diodes ~as long as you insure your polarity is all correct and static is addressed {i havent considered static nor taken measures} you should have a trouble free build ~i m pretty confident of it