Quote:
Originally Posted by erick
Something to note, come next winter. My understanding is that green lasers have a lower working temperature (I see some 30mW+ ones advertised as 15 deg C minimum operating temperature). On a cold night, your light output may drop away. Though it may be the batteries, it's more likely too cold for the laser to operate. I keep mine in my top pocket between uses. Yes, true that is not much help if you have it accurately lined up in a mount - taking it out may lose your alignment.
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I did a bit of work on experimenting with lasers and batteries at low temperatures. During the winter months, I tried several times to use my 30mW laser for aligning the GoTo but the laser was barely visible even on the palm of my hand. Not knowing what the problem was I got some bits from a local electronics store and created a 6V regulated power supply which I connected directly to the laser (I hacksawed the end off the tube and soldered directly to the circuit board connecting to the laser itself). I trimmed the output voltage to 3.00Volts and room temperature. If I put the whole assembly in the freezer for an hours or so, the voltage drops to 3.98V but the laser is totally OFF, not a peep out of it. As it warmed up again it came back to life. Putting it in the fridge at 4 degress gave an output of 3.99V, and the laser is still OFF.
Since then I have had the scope out on nights of around 10 degrees and the laser takes a minute or so to warm up, and I know the voltage should be within a wisker of 3V so the critical thing appears to be to keep the laser warm, although who knows what the batteries will do when they are cold too. At least now I know if I leave the laser on for a while it will come to life, eventually. The power supply has 4xAA batteries rather than just 2xAAAs so it has enough kick to warm the laser up. If you are interested in such a project, I can send you details.
BTW, I use a lumicon bracket which fits on it's own mount, that way I still have the finder. However, having done all this work on it, I now find I usually use the TelRad to align the scope now and rarely use the laser anyway (the only reason I mounted it was for initial alignment).