Just thought I'd share this PL520 build I did a few months back to add something to the sound of tumble weeds rolling through the lands of LPF builds lately :)
I wanted switchable output with the lowest output having some degree of eye safety (keeping in mind something should never actually be considered "eye safe" from any laser) so I gave it outputs of <5mw, ~40mw and ~110mw in a switching network I designed using a double pole switch that controls the output by changing between program resistors with the off position being the lowest setting, the other two positions adding parallel resistance (so, technically less resistance...higher current) on top of the base resistor set. Linear regulator is the LM317 with ripple smoothing, spike filtering and full bypass caps Eight Ways to Sunday. I found the G7 had a nice clean output and stuck with it, also tried the acrylic which looked good as well but the output fell noticeably and the 3 element just looked dirty (bad dirty).
Speaking of dirty, I couldn't stop laughing after looking at the picture of the LM317 mounted to the case before I soldered it. Seriously didn't end up like that on purpose.
Here's the pics...
I wanted switchable output with the lowest output having some degree of eye safety (keeping in mind something should never actually be considered "eye safe" from any laser) so I gave it outputs of <5mw, ~40mw and ~110mw in a switching network I designed using a double pole switch that controls the output by changing between program resistors with the off position being the lowest setting, the other two positions adding parallel resistance (so, technically less resistance...higher current) on top of the base resistor set. Linear regulator is the LM317 with ripple smoothing, spike filtering and full bypass caps Eight Ways to Sunday. I found the G7 had a nice clean output and stuck with it, also tried the acrylic which looked good as well but the output fell noticeably and the 3 element just looked dirty (bad dirty).
Speaking of dirty, I couldn't stop laughing after looking at the picture of the LM317 mounted to the case before I soldered it. Seriously didn't end up like that on purpose.
Here's the pics...