audioguru

Many laser diodes have a photo-diode inside that is used with an external transistor to adjust the brightness. I don't know if these laser diodes have the feedback transistor and I don't know how much extra voltage the transistor needs.
The transistor also might limit the current.

The datasheet for the laser diode assembly will tell all.

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Uncle $crooge

audioguru

The "manufacturer" AixiZ Service & International, LLC is just a distributor for 184 companies that make laser diodes and many other optical items.
The search on the website did not know of the part number for the laser diode.

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Uncle $crooge

Willie TwoFinger

Torben... thanks for all the info, it is clarifying much for me...

audioguru... yeah I was thinking that would be the case. I'm pretty sure that they're actually made somewhere in China. I couldn't find that info on their web site....

audioguru

When you buy parts from E-Bay then you don't get a datasheet and you don't get the spec's that are needed to use the parts properly.

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Uncle $crooge

Willie TwoFinger

Another question has come up...

"We need to find out the formula for the amps when we wire it series/parallel. Is it just straight up division?

If I had lets say 200 diodes wired into four groups of 50 -and each of those four was wired series, and I used a 12 volt adapter- then would the total amps be 1/4th what it would be?"

Willie TwoFinger

Also, how big of a resister can be placed on each diode if I so desired? I know that is a lot but... I'd do it... is it even feasible?

Torben

Hi Willie,

OK, for this I'm going to assume we're just using bare LEDs here (not laser modules with integrated electronics).

Assumptions: all LEDs are 3.2V LEDs which want 50mA; we have a 12V power supply. So Vled = 3.2V; Iled = 50mA, and Vsupply = 12V.

The short answer to your questions is "No, the total current drawn would not be 1/4 of of just wiring them all up in parallel. It would be 0." That is, 200 3.2V LEDs wired in 4 strings of 50 LEDs each would not even try to light up from a 12V power supply. Remember that you need (Vled * number of LEDs per string) volts to run the thing. (3.2 * 50) = 160V. You are not going to get a 160V device to run on a 12V power supply without some kind of boost converter. If you used a 160V+ power supply then the current draw would be 200mA (50mA * 4).

With a 12-volt supply your longest string of LEDs can be 3 LEDs long. Why? Because 3.2V goes into 12 at most 3 times. So you could do 66 groups of 3 LEDs (with 2 LEDs left over), or 100 groups of 2 LEDs.

Make sense?


Torben

Willie TwoFinger

Torben...

Yeah, it's starting to sink in... Much thanks!

audioguru

Everybody is just guessing without detailed spec's.
The laser assemblies might need external current-limiting or not.
What is their minimum and maximum allowed voltage and current?

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Uncle $crooge