Updates to my mechanical set
Posted: Sat Mar 24, 2018 2:27 pm
I decided to update my old mechanical television that I first built when I was 12. Here is the other thread I made: viewtopic.php?f=1&t=2413
I made a new disc with the holes drilled more precisely with a smaller bit (1mm instead of ~2.5). It's not perfect, but it is certainly much better.
I scrapped the nail bearing and used a video head from an old broken VHS camcorder and also replaced the pulley on the disc side with a 3D printed one (I have a 3D printer now )
I also built a sync circuit based on an Atmega328P microcontroller. I have been running it at 15 FPS to reduce the flicker compared to that of 12.5 FPS. But I would like to get it even higher.
The cradle for the video head was 3d printed. As was a plate to make it flat so the disc can sit against it. I didn't disassemble the head and free the bearing and just used it as is and only removed the connections and the BLDC motor. The video head conveniently has two threaded holes which I use to attach the disc. It might be ideal to have 4 but I haven't had any issues so far.
The sync board isn't very pretty but it is functional.
Sync separation looks good!
Unlike most designed I see here, I used a reed switch next to the the disc and a tiny rare earth magnet glued to the disc to provide a frame sync pule (no line sync).
The reed switch provides a solid, sharp signal to the microcontroller. I had much better results out the reed switch than I have with infrared emitters and phototransistors in the past.
Unfortunately I don't have any pictures of it fully assembled right now with the motor, pully and rubber band (err...belt).
And natürlich results:
Now the next biggest problem I can see is that it lacks DC restore so pure white (er...red) displays fade out while black ones glow. There is also vertical banding.
Anybody have any suggestions what I should do to improve this?
I made a new disc with the holes drilled more precisely with a smaller bit (1mm instead of ~2.5). It's not perfect, but it is certainly much better.
I scrapped the nail bearing and used a video head from an old broken VHS camcorder and also replaced the pulley on the disc side with a 3D printed one (I have a 3D printer now )
I also built a sync circuit based on an Atmega328P microcontroller. I have been running it at 15 FPS to reduce the flicker compared to that of 12.5 FPS. But I would like to get it even higher.
The cradle for the video head was 3d printed. As was a plate to make it flat so the disc can sit against it. I didn't disassemble the head and free the bearing and just used it as is and only removed the connections and the BLDC motor. The video head conveniently has two threaded holes which I use to attach the disc. It might be ideal to have 4 but I haven't had any issues so far.
The sync board isn't very pretty but it is functional.
Sync separation looks good!
Unlike most designed I see here, I used a reed switch next to the the disc and a tiny rare earth magnet glued to the disc to provide a frame sync pule (no line sync).
The reed switch provides a solid, sharp signal to the microcontroller. I had much better results out the reed switch than I have with infrared emitters and phototransistors in the past.
Unfortunately I don't have any pictures of it fully assembled right now with the motor, pully and rubber band (err...belt).
And natürlich results:
Now the next biggest problem I can see is that it lacks DC restore so pure white (er...red) displays fade out while black ones glow. There is also vertical banding.
Anybody have any suggestions what I should do to improve this?