Re: Micro-Drive laser driver *NOW ADJUSTABLE*
Ok.. first off, there are instructions posted on my website, in the descriptions for each item. Yes, the thru-hole are the input, the LD is positive diode output, GD is negative diode output (but it is common to the negative input as well).
Next, the Test Load. Out of the (many) hundreds of these things I've sold, you're the second person to ask about that and the only one to complain... so congrats. I don't do anything without reason, though. And, you DON'T have to use desolder wick or a vacuum pump, just heat up the joint and it will likely break itself. If not, hit it with a little flux and try again (if you're soldering, you should have flux).
Anyway, the reasons for why I set it are: if you power the test load up without a setting, you'll pop the small resistor on there almost instantly at any substantial current. Since the output voltage does NOT matter if you're just setting the current on my driver (most common use for the Test Load) and using the RED voltage allows for the minimum amount of input voltage to the driver, that is what I set it to. Plus, I've been doing that since I first made these, which is when red diodes were more commonly used, so I continue for the sake of consistency as well.
When measuring on the test load, it doesn't matter what hole each lead goes to as you're just looking at the number, not the sign. So whether it is positive or negative makes no difference, the integers will be the same. The forumula "1mV = 1mA" is derived from Ohm's Law since you are measuring the voltage across a 1 ohm resistor to find current. Where V = I * R, you see R = 1, so V = I * 1 is the same as V = I, or if using the units, 1mV = 1mA.
Let me know if you have any other questions.
