I recently bought a bag of 100 5mw 4.5V laser diodes (the spec said they have "driver: out"). My idea was to connect two and two of these in series to get something that needs 9V, and then connect about 70 of these diodes in parallel and run it off a 9V battery.
This didn't work as expected.
Just using 6-8 diodes, the light was already getting visibly dimmer. I figured there could be a short somewhere, but it seemed everything was in order. The 9V battery was used, but only for driving a few LEDs for a few hours.
So I decided to try something else. By using a battery pack of 6 1.5V batteries, the laser diodes were shining at full force again. I tried using about 20 of the diodes in the same setup as above, and still everything seemed fine.
Thus it seems I'm stuck with AA batteries for my setup.
Anyway, my questions are:
Why is this happening?
Are there not enough amperes to drive the lasers?
Why is the battery pack able to drive the lasers when the 9V battery isn't?
Is there any way I can calculate the approximate number of lasers the batteries can drive?
Will an amplifier or extra driver be able to fix this so I can still use the 9V battery?
Bonus question: If the answer to 5 is "yes", can I find such an item on eBay? I just need an example of what to look for since I'm just a hobby electrician.
Since you good folks asked for it, here's all the data I have regarding the laser diodes:
A brand new 9V battery was able to drive the diode arrangement after all. There appears to be a small resistor on the diode board, so I took my chances that the diodes would not blow just using them as described above (and I had spent way too much time on this Halloween cannon already to bother soldering 40 or so more things into the setup). Last night I used the cannon for a full entire night, and the lasers were still jolly good by the end of the evening.
Plus the cannon looked damn good in a dark nightclub with some artificial fog :)