FireMyLaser said:
I know that the current is the same anywhere in a serial circuit, but maybe there is some parallel stuff in there? Do you know that I mean?
It's damn hard to explain. :-[
I know exactly what you mean, but even if some current was bypassed in parallel with the diode, the total current would still stay the same with different battery voltages if it was regulated. But that only makes sense if it is a constant current source, which can not be adjusted otherwise, like the AMC. The only example i can think of right now, where the current in would change with the voltage, but the current out would stay the same would be a buck regulator (or boost but not in this example). But there the current would increase, as the battery voltage would drop. A buck regulator would make the most out of two batteries, because they work at a high efficiency. Compared to that, a 317 wastes more than an entire battery.
But in most cases you can get a pretty good idea of the LD current by measuring the current going into the circuit.
What we can not know for sure is the exact current through the LD itself, because the circuit can also consume a few mA, but i if the current continues to drop, i'm pretty sure it is unregulated. I'm gonna wait for StyroPyro to measure with the batteries even more empty than they are now, and then we will know for sure.
Without regulation the current peaks when the batteries are full, then it levels out and remains almost constant for a while and drops very slowly, but steadily. In the 20A DMM range you wouldn't even notice the change for a while. In the end it starts dropping fast and the brightness decreases.
This is for example the behaviour of my first red, which was direct drive from a Li-PO. It is also what most green lasers behave like.
Styro: Don't wait untill they are completelly empty. Even a regulated circuit would drop out of regulation by then. It is better to make the nex measurement somewhere in the middle of the battery capacity. It should come out at around 270-280mA soon with these batteries. The current consumption is almost identical to the KD50 on the same battery.
EDIT: A quicker way to test for regulation would be to go to a lower DMM range (2A). If the current was regulated, you shouldn't see much difference from before, and if it's not, there would probably be a noticable difference immediatelly (simply from the larger DMM resistance), and you would see it slowly dropping.
Otherwise, you are right, i am tempted by this laser, just modding it would be lots of fun. But i really think i wasted enough money on lasers for a while.. I promised my Laser Addicts Anonymous sponsor i wouldn't buy more lasers.. Or did i say green lasers?