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

Driving dual LPC-826 the right way?

LaserAdct

LaserAdct

0
Joined
Dec 22, 2010
Messages
227
Points
18
Hi all.

I am about to combine two LPC-826 with a PBS and was wondering the optimal/best practice way of driving these diodes. I am using flexmod p3 but cant quite figure out if I should drive them both of 1 driver or seperate.

Any pros and cons I should be aware of? Is it possible to hook up 1 driver in a way that it wont kill both diodes if one of them goes poof?

If using 1 driver is there anything I should be aware of? What is the proper way of hooking up 1 driver to two diodes (resistance needed etc)?

Best regards.
 





kiyoukan

kiyoukan

0
Joined
Oct 24, 2009
Messages
2,555
Points
48
Depends you can drive them in series and the driver will take the extra voltage once one dies and turn it into heat or you can do parallel but then if one die the other one goes.
I think thats how it works but its 3.30am so i might just be crazy.
 
Sigurthr

Sigurthr

0
Joined
Dec 11, 2011
Messages
4,364
Points
83
If using one driver wire the diodes in series (2x Vf, 1x If) so that if one fails double current is not allowed to go through a single diode.
 
LaserAdct

LaserAdct

0
Joined
Dec 22, 2010
Messages
227
Points
18
Ahh I see, so it is actually possible to hook it up so both wont blow if one of them does! Perfect. I am not very skilled in the electronics department unless its building from schematics and stuff like that :)

So did I understand this correct (this setup will not blow both, but just turn the excess voltage into heat):

"FMP3+" -> "LD1+" -> "LD1-" -> "LD2+" -> "LD2-" -> "DRV-"

Will I need any resistors in between, or is this the "final" setup?

Best regards
 
Sigurthr

Sigurthr

0
Joined
Dec 11, 2011
Messages
4,364
Points
83
That looks fine. You shouldn't need to add any resistors, that's mostly for current equalization in parallel set ups, which would still cause a good diode to pop when a bad one fails.
 
Blord

Blord

0
Joined
Dec 24, 2007
Messages
5,356
Points
0
I would have chosen a buck driver for two LPC-826 in series. If one diode fails but still letting the electricity thru then the buck driver will reduce the output voltage to met one diode. The input current of the driver will also be reduced. The remaining diode will still be regulated.

I think now the story will be the same for a boost driver. Only a linear driver may cause trouble.
 
LaserAdct

LaserAdct

0
Joined
Dec 22, 2010
Messages
227
Points
18
Its for a RGB scanner build and my flexmods have proper heatsinks and will get a fan attached to the heatsink in the final setup. I am feeding 12v to the driver anyway so atm with 1 diode attached I have the same heat amount and it barely gets warm.

In a handheld host a different driver would indeed be better suited :yh:
 
Wolfman29

Wolfman29

0
Joined
Jan 14, 2011
Messages
3,816
Points
63
Remember, when diodes die, there are typically two options: either A) they LED and take the same current, just don't emit collimated light. In that case, no matter the set-up, your good diode will be fine, you will just half the light. Or, B) they go completely dead, meaning that the bond wires are no longer connected, which would break your circuit. This is in series, remember.

In parallel, if it goes LED, then you're still fine, and if it goes dead, then yes, your other diode will poof too.
 
LaserAdct

LaserAdct

0
Joined
Dec 22, 2010
Messages
227
Points
18
Thank you for that specification Wolfman I feel more confident hokking up the second module now :beer:
 
M

mattco2

0
Joined
Feb 12, 2012
Messages
237
Points
0
2 ghost drives would be the chapest option at 14$ and if one dies it dies doesnt take the other with it
 
Cyparagon

Cyparagon

0
Joined
Sep 12, 2007
Messages
9,399
Points
113
Remember the diodes are not case neutral. If you user series, be sure the cases are electrically isolated, or one will not light.

kiyoukan said:
Depends you can drive them in series and the driver will take the extra voltage once one dies and turn it into heat or you can do parallel but then if one die the other one goes.
I think thats how it works but its 3.30am so i might just be crazy.
Click to expand...

In the first scenario, you're assuming they fail short-circuit.
In the second scenario, you're assuming they fail open-circuit.
The most common failure mode (by far) is COD, where the electrical loading properties change very little, if at all.
 
You must log in or register to reply here.




Top