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Wrong on both counts. Assuming that you could observe the dot on the sun, you would see it travelling at 5c; and if that's all you can see, then you have no idea where the beam originated and how much time it spent to get there. So the fact that the light takes 8 mins to reach the sun in this...

Yep. Or for making things fluoresce.

With a 500mW green the current draw on the battery will most likely be in excess of one amp. That will usually cause a significant voltage sag (as well as resulting in a much faster drain than you might expect, as the capacity is for a standard 0.1C =10 hour discharge). Try getting a good...

It's now a 0.5mW pointer on the DX web site...

Not really. The dot will appear very dim, and it won't even look like a dot. Red and green are much better for that. It's a bit better if you use the BR for star pointing: here, the lesser visibility due to the wavelength is partly compensated for by the higher backscattering. Still, again the...

An ammeter has a very low internal resistance. It might cause the short-circuit protection of the IC to kick in and thus result in a false reading. Using a test load is simply for simulating the real operating environment and preventing that sort of surprise.

What happened?

No-one ever said that the speed of light is constant. It's the speed of light in a vacuum that's constant (and cannot be exceeded). Also, it's not a belief, it's an assumption (an axiom - like Euclids axioms of geometry) from which all the strange effects (which have been verified with a very...

It's amazing, the things there are on youtube... I wonder how much thrust they have?

In a similar test during the SDI years, the beam hit a light sensor which then triggered an explosive charge in the target...

The '100s of miles' would only work at high altitudes, where the air is thin and clean, that's why you can't put it on the ground. As for the 'rogue nuke': no-one would fire that in a missile at the US. You'd just ship it in in a standard cargo container. This ABL is just another high-priced...

Also it's quite unlikely that the beam was really directly reflected into your eye - that would take a rather remarkable precision in alignment and orientation of mirror, laser and eye. It's likely that the beam passed somewhere close to your eye (a few cm distant) and you got a bit of spill...

While it won't help you, overstating the power of hi-power green lasers seems to be the industry standard... they're known to vary a lot due to their complex way of generating laser light. For that price ($76) you can't really expect more.

Good idea, however it doesn't work with "constant current" drivers obviously... here, you'd need a Zener diode with a voltage threshold above the normal load (laser diode or LED) and below the max rated output voltage of the driver as an open circuit protection.

You may not have noticed that there's a "View poll results" link for those who haven't voted (yet).

What pullbangdead says has been my advice all along - leave off the capacitor. First, electrolytic caps are simply useless if you want them for spike protection - their parasitic inductance is way too high. Also, any "despiking" capacitance has to be very close to the regulator IC, for the same...

If one assumes 3.2V input from the batteries and a boost driver supplying ~5.5V@180mA output to the diode, the figures would work out...

What you see from a few meters away is not the real dot, it's a sort of ghost. That's because for light near the low-wavelength limit of visibility, normal eyes are effectively quite shortsighted, so you can't focus on it (unless you're farsighted). Also the eyes sensitivity for that light is...

BIG doesn't begin to describe it... :knight: