The First B/W Phaser Ones, Page 2
As the knob turned, a link inside the body connected from the wheel to the round Plexiglas rod which would turn into the plate, forcing it to slide across the face of the Plexiglas rod and thus raise as it slid up. This action would raise the plate about 1/4" because it which was hinged at the front and the rear part of this plate would ride up on the Plexiglas.
Only then at the very end of the rotation, at the highest setting, could you turn it a little further to light the light, or to fire the phaser one.
Design-wise, this means it could only fire on its highest setting!!But we know that it did fire on other settings for this was what we have seen on the screen.
These mechanical facts have been right in front of us for so many years. In the old paperback book "The Making of Star Trek" with those poor black and white photographs in it, the open phaser one has a visible knob, the link to the Plexiglas and the battery holder.
There was a small raised round aluminum button/rod on the bottom of the phaser one on some models. No one knows why it's there. Was it a mock trigger? A knob to aid gripping the phaser one? (Very likely, as the little darlings were slippery) Or simply a knob to help remove the bottom when servicing it? Who knows? (Write me if you really do know, have ID and proof ready.) UPDATE
The non-working models of both the pistol and hand phasers were mostly cruder than the above described. They had poor detailing, that is, when detailing was even remembered, and misshapen bodies, Velcro-glued for "invisible" holsters, etc.
Well, that's it, almost every detail known to human and Vulcan on the history of the black and white classic phaser one.