Willie TwoFinger said:
rjvh, or Torben ...
What are the advantages of putting them in series?
As you can tell, I know little on how this all works!
Thanks!
From the image you posted it looks like it would contain its own current source circuit, but it's impossible to tell for sure. The specs you posted don't list typical diode-type specs (such as forward voltage etc). I suspect this means that it does in fact include a current-limiting resistor BUT I don't know for sure. If you blow them out using this post as a recommendation, it's on your own head.
As for the series/parallel thing: diodes are not perfect devices. If they were perfect then there would be no problem wiring them in parallel but in reality they vary slightly from one diode to the next, even of the same type/colour/rating/etc. So when you put them in parallel they do not get a perfect distribution of the current; some of the devices draw more and the others less. You can get runaway effects where one draws all the current and dies. Then the next one pulls the current and dies, and so on.
You can get around this problem in a few different ways. One would be to leave the LEDs in parallel but put a current-limiting resistor in series with each LED. You can probably quickly see why this is ridiculous for large numbers of LEDs: you have one resistor for each LED. Also, the current drawn is high (Iled * the number of LEDs).
Another solution is to put all the LEDs in series and just use 1 resistor to limit current. Since in a series circuit the current is the same at all points in the circuit, the current over the individual LEDs can't get unbalanced when they're wired in series. The problem with this solution is that while the current drawn stays low, you need a voltage of (Vled * the number of LEDs) volts to drive the series. For 155 3V LEDs that would mean you'd need 465V-plus power supply.
So a common solution is to compromise by arranging the LEDs in several equal strings, with each string having its own resistor, and putting the strings in parallel. Then the voltage needed is (Vled * number of LEDs per string) and the current drawn is (Iled * number of strings)--you can vary the number of LEDs per string and the number of strings to match your power supply.
Hope that made some kind of sense. Disclaimer: I'm no electrical engineer. I'm just some guy with a soldering iron and this is a hobby.
Erm. One more thing. You have a 3.3V power supply and 155 lasers which require at least 3V each, and which draw 50mA (from the spec sheet you posted--I know this disagrees with your first post but design for the worst case scenario). You should be fine putting them all in parallel except your power supply will be over spec (155 * 50mA = 7.75A; the power supply is rated at 7A). You could try running them in groups of 2 to bring the current draw down to around 4A but then you're trying to run 6V per string on a 3.3V supply.
I hate to say it, but unless I'm missing something, I don't think your power supply is up to the task of running all 155 laser modules--at least, not while staying within its rates specs. I hope I'm wrong. If I'm right, I hope you kept the receipt.
Good luck,
Torben