Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers

LPF Donation via Stripe | LPF Donation - Other Methods

Links below open in new window

ArcticMyst Security by Avery

LPC826 - Case Pisitive or Negative?

adambowker

adambowker

0
Joined
Feb 26, 2014
Messages
231
Points
18
EDIT: Title should say "Positive," not "Pisitive," and I don't know how to change it :p

Hi all -

Jmillerdoc has recently been kind enough to send me an LPC826 diode and 12mm module for free to help with my first build (thanks again man :D).

I have decided on the SurvivalLasers C6 host and their driver set at something like 465mA.

The only problem I have is that I don't know if the LPC826 is case-positive or case-negative. I have been told it is case positive, meaning I need an anodized heatsink, but I was also told it was case negative and not to get an anodized one. Can someone clarify it for me? I don't want to wire it the wrong way and blow my only diode if I can prevent it.

Thanks in advance, everyone!
Adam
 
Last edited:





NKO29

NKO29

0
Joined
Jun 6, 2013
Messages
861
Points
28
lpc.png

:)
 
Seoul_lasers

Seoul_lasers

0
Joined
Jul 4, 2008
Messages
2,499
Points
113
adambowker said:
Thanks - so it IS case negative? If so I won't need an anodized heatsink, right?

Adam
Click to expand...

errr.... ummmm....

I am not sure by your definition of what Anodized means? However,
Anodizing is a way of protecting or coating metals &
It's got nothing to do with polarity.

:thinking::thinking::thinking::thinking:


You can use virtually any metal to use as a way of housing a laser diode, be it Copper, brass, Silver or even gold for that matter...
just as long as it can conduct heat well.
:can: :can: :can: :can:
 
adambowker

adambowker

0
Joined
Feb 26, 2014
Messages
231
Points
18
Seoul_lasers said:
errr.... ummmm....

I am not sure by your definition of what Anodized means? However,
Anodizing is a way of protecting or coating metals &
It's got nothing to do with polarity.

:thinking::thinking::thinking::thinking:


You can use virtually any metal to use as a way of housing a laser diode, be it Copper, brass, Silver or even gold for that matter...
just as long as it can conduct heat well.
:can: :can: :can: :can:
Click to expand...

I know anodized has nothing to do with polarity.

I was talking about using the anodized heatsink to isolate the diode from the host if it had been case positive; if it's anodized it won't conduct electricity.
(At least that's what I've been told I need to do with case-positive in the past. Here's a picture I found on the forums showing the diode isolated from the host in case-positive:
Screen_Shot_2014_03_23_at_9_26_18_PM.png
)
 
123splat

123splat

0
Joined
Jan 14, 2011
Messages
424
Points
0
NO!! You do NOT want the Anodized sink.
Seoul, et.al., Anodizing creates an INSOLATING film on the material. If one was to use an anodized heatsink, in a case where the sink is used as part of the conducting path, they would have to provide a conducting path around (use the diode's case pin in this incidence), or through (remove the anodizing), the sink. Anodized heatsink is a waste of time and effort.
 
adambowker

adambowker

0
Joined
Feb 26, 2014
Messages
231
Points
18
123splat said:
NO!! You do NOT want the Anodized sink.
Seoul, et.al., Anodizing creates an INSOLATING film on the material. If one was to use an anodized heatsink, in a case where the sink is used as part of the conducting path, they would have to provide a conducting path around (use the diode's case pin in this incidence), or through (remove the anodizing), the sink. Anodized heatsink is a waste of time and effort.
Click to expand...

Thanks! However, if the diode was case positive, you WOULD need an anodized heatsink... right?

And, just to confirm again... the LPC826 is case-negative. Correct?
 
Seoul_lasers

Seoul_lasers

0
Joined
Jul 4, 2008
Messages
2,499
Points
113
adambowker said:
I know anodized has nothing to do with polarity.

I was talking about using the anodized heatsink to isolate the diode from the host if it had been case positive; if it's anodized it won't conduct electricity.
(At least that's what I've been told I need to do with case-positive in the past. Here's a picture I found on the forums showing the diode isolated from the host in case-positive:
Screen_Shot_2014_03_23_at_9_26_18_PM.png
)
Click to expand...

I see what you're saying now. You had me a little confused.
The word you were looking for was electrically isolating.

:whistle:
 
KRNAZNBOY

KRNAZNBOY

0
Joined
Mar 29, 2013
Messages
1,221
Points
63
Yes the LPC is a case negative diode. This is great for all conventional drivers as they are continuous GND. As long as you use a x-boost/drive, or flexdrive, microboost, etc you will be fine with an un-anodized heat sink.

If you go with say an AMC7135 Driver, which is continuous positive, you will need a case positive diode or an anodized heatsink



Hope this helps!

-Matt
 
adambowker

adambowker

0
Joined
Feb 26, 2014
Messages
231
Points
18
KRNAZNBOY said:
Yes the LPC is a case negative diode. This is great for all conventional drivers as they are continuous GND. As long as you use a x-boost/drive, or flexdrive, microboost, etc you will be fine with an un-anodized heat sink.

If you go with say an AMC7135 Driver, which is continuous positive, you will need a case positive diode or an anodized heatsink



Hope this helps!

-Matt
Click to expand...

Thanks Matt! I am most likely going to order this SurvivalLasers buck driver at 530mA - that'll work right?

EDIT: Forgot to say that I'm getting the unanodized aluminum heatsink as well :p
 
Last edited:
IsaacT

IsaacT

0
Joined
Aug 25, 2010
Messages
5,947
Points
83
Buck Drivers should be fine. And a flexdrive would be okay. But you need to not use a Microboost on any red diodes. Just a rule of thumb that you don't boost reds. Their forward voltage is low enough that they don't need it. If I remember correctly of course.
 
Seoul_lasers

Seoul_lasers

0
Joined
Jul 4, 2008
Messages
2,499
Points
113
wannaburnstuff said:
Buck Drivers should be fine. And a flexdrive would be okay. But you need to not use a Microboost on any red diodes. Just a rule of thumb that you don't boost reds. Their forward voltage is low enough that they don't need it. If I remember correctly of course.
Click to expand...

Red LDs typically have a forward voltage of about ~ 3.2-3.5v ... typically never exceeding 3.5v.

Correct you are! :p
 
DTR

DTR

0
Joined
Jun 24, 2010
Messages
5,684
Points
113
adambowker said:
Thanks! However, if the diode was case positive, you WOULD need an anodized heatsink... right?
Click to expand...

In that case you would want a driver that regulates via the negative side and can run with a continuous positive. Like a IR driver used in most green DPSS pointers.;)
 
Jmillerdoc

Jmillerdoc

0
Joined
Oct 3, 2011
Messages
899
Points
0
You can still use an anodized heat sink with a case negative diode. Instead of using the heat sink as part of the current path you just need to connect the diode directly to your driver. Just use the negative pin wired directly to the driver's LD - output. If you already bought the anodized heat sink this is much easier to do than trying to remove the anodizing to make an electrical path to the diode.
 
Jmillerdoc

Jmillerdoc

0
Joined
Oct 3, 2011
Messages
899
Points
0
Since we've got that picture of the diode up top and I've always wondered what the "not used" pin is for.....what is the "not used" pin not used for? Surely it has a purpose? Why would a manufacturer go through the trouble of putting it there for no reason? The only thing I can think of is they just had a few million diode bodies with these pins laying around that were intended for another use and they decided to make something else with them that didn't require the pin. Someone here know why we have this extra pain?
 
You must log in or register to reply here.




Top