Build a cheap open loop galvo

[WildRice]

I made a few of these years ago when I first started playing with HeNe's. I dont have any pics so I will try to describe as best I can. First find a hobby motor, one of the round 3v ones worked well. Put something on the motor shaft, something like a worm gear, and put a vertical mark on it with a sharpie marker. Now put a small voltage on it and hold the motor shaft, if you let it turn SLOWLY you can fell where the brushes hit the different contacts. Mark these positions on the motor casing to line up with the mark on the shaft. There should be three. Now put the shaft position in between two of the marks on the motor. This sets up a smooth + and - swing. Now what I did was unbend a paperclip and epoxied it to the side of the motor on the side between the marks. the clip was bent away from the motor then back up. Then a spring was attached, 1 end on the clip and the other on the motor shaft on the mark.
What this did was to hold the motor innards at the position in the middle of one of the electrical segments. When a small voltage is applied either + or -, the motor would twist either CW or CCW. The resistance of the spring would restrict movement, and when current was removed, it would return to center (or close).
This is a LOW budget galvo, not terribly accurate, but it does work. These can then be mounted for use as an alternative X-Y setup.
OH, glue a small morror on the motor shaft. The opposite of the gear can be sanded down to better mount the mirror.

Jeff

 

[jtice]

hmmmm, thats a good idea Jeff!
very creative cheap way of doing it.
Though, after a long while, i bet it burns the motor up, but, eh, who cares when its that cheap. /ubbthreads/images/graemlins/smile.gif