Construction Diary -- Part 2, Spinning the Nipkow Disc
Posted: Sat Apr 07, 2007 11:14 pm
I started tonight thinking about how electric motors work, and how to hook up my Nipkow disk. Fortunately, just about all the work has been done for me already.
Firstly, I noted that the sample motor control circuit (see http://www.taswegian.com/NBTV/forum/viewtopic.php?t=122 ) has 12V powering the motor. I figured I'd give the two motors I have a go (these were kindly supplied by Peter Yanczer with the Nipkow disk I bought from him).
While I was rather tentative at first (no explosion?...! great) after a while it became obvious that electric motors were a no-brainer. I plugged it in to the 12V supply. It spun. After I'd had a bit of a play trying to stop the motor with my fingers (testing the torque), I figured I might as well hook up the Nipkow disk to the hub thingy, and then hook up the disk to the motor via a rubber belt (all held in my hands).
It's a bit tricky juggling, but I can report a few observations...
1) Holding a spinning nipkow disk, an electric motor, and keeping a rubber pully/belt aligned and tensioned between the two is very difficult.
2) Rapidly spinning Nipkow disks are dangerous!!!!
I have no idea how rapidly the disk was spinning in the end, but I did get a good feel for what sort of tension was required in the belt to give good 'traction', and got a fair idea of where, relatively, the motor would need to be mounted.
At this point I realised that both my motors spin clockwise when looking down on them from 'above'. This is unfortunate, because I want my Nipkow disk to spin anticlockwise (scanning from bottom right, UP). I also want my motor and hub to be BEHIND relative to the viewer. This means that the body of the motor needs to be between the spindle and the hub, and there's not really a lot of room there. Enough, but it's a bit of a spanner in the works.
Attached is a picture showing how the motor will be mounted, also showing the rubber belt and the hub attached to the Nipkow disk.
All in all, it seems *really* simple to me, and in theory I could build up a bit of a rig to hold it all stable, and in almost no time at all actually be trying to view a picture on my "monitor".
Firstly, I noted that the sample motor control circuit (see http://www.taswegian.com/NBTV/forum/viewtopic.php?t=122 ) has 12V powering the motor. I figured I'd give the two motors I have a go (these were kindly supplied by Peter Yanczer with the Nipkow disk I bought from him).
While I was rather tentative at first (no explosion?...! great) after a while it became obvious that electric motors were a no-brainer. I plugged it in to the 12V supply. It spun. After I'd had a bit of a play trying to stop the motor with my fingers (testing the torque), I figured I might as well hook up the Nipkow disk to the hub thingy, and then hook up the disk to the motor via a rubber belt (all held in my hands).
It's a bit tricky juggling, but I can report a few observations...
1) Holding a spinning nipkow disk, an electric motor, and keeping a rubber pully/belt aligned and tensioned between the two is very difficult.
2) Rapidly spinning Nipkow disks are dangerous!!!!
I have no idea how rapidly the disk was spinning in the end, but I did get a good feel for what sort of tension was required in the belt to give good 'traction', and got a fair idea of where, relatively, the motor would need to be mounted.
At this point I realised that both my motors spin clockwise when looking down on them from 'above'. This is unfortunate, because I want my Nipkow disk to spin anticlockwise (scanning from bottom right, UP). I also want my motor and hub to be BEHIND relative to the viewer. This means that the body of the motor needs to be between the spindle and the hub, and there's not really a lot of room there. Enough, but it's a bit of a spanner in the works.
Attached is a picture showing how the motor will be mounted, also showing the rubber belt and the hub attached to the Nipkow disk.
All in all, it seems *really* simple to me, and in theory I could build up a bit of a rig to hold it all stable, and in almost no time at all actually be trying to view a picture on my "monitor".