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FlyMario wrote:Good evening,
I am working on a home project to build a Mechanical TV. Currently I am trying to work out the Nipkow disk. I am using a 12" (304.8mm) vinyl record as the disk itself and trying to work out the hole sizes to use. I read somewhere to use a 1/16" (1.57mm) drill bit. I was pretty pleased with that notion because I felt I would probably have no issues drilling through records at that size. In solidworks I drew the disk and placed these holes and was not pleased. The pattern did not look like it would be correct for a Baird style tv. The hole patterns would cover too much are. Thinking there would be less light let through away from the center I allowed the holes to overlap (1.2mm center to center) but still it looked much more wide than tall.
So guess I am looking for someone to maybe give me advice. Should the holes be overlapping more or am I just going to get a much smaller bit. I am going for 32 holes.
Thanks for any suggestions you can offer.
FlyMario wrote:Good evening,
I am working on a home project to build a Mechanical TV. Currently I am trying to work out the Nipkow disk. I am using a 12" (304.8mm) vinyl record as the disk itself and trying to work out the hole sizes to use. I read somewhere to use a 1/16" (1.57mm) drill bit. I was pretty pleased with that notion because I felt I would probably have no issues drilling through records at that size. In solidworks I drew the disk and placed these holes and was not pleased. The pattern did not look like it would be correct for a Baird style tv. The hole patterns would cover too much are. Thinking there would be less light let through away from the center I allowed the holes to overlap (1.2mm center to center) but still it looked much more wide than tall.
So guess I am looking for someone to maybe give me advice. Should the holes be overlapping more or am I just going to get a much smaller bit. I am going for 32 holes.
Thanks for any suggestions you can offer.
smeezekitty wrote:You wont want to use constant speed on the disk. It needs to be phase locked to the signal. Otherwise you will have rolling or an out of position picture.
FlyMario wrote:smeezekitty wrote:You wont want to use constant speed on the disk. It needs to be phase locked to the signal. Otherwise you will have rolling or an out of position picture.
So, do you guys have videos recorded for this kind of system already or do you convert video (downscale) for these Televisors? I was looking for some to download to try and started to believe I will have to create them myself.
Thanks,
FlyMario
smeezekitty wrote:FlyMario wrote:smeezekitty wrote:You wont want to use constant speed on the disk. It needs to be phase locked to the signal. Otherwise you will have rolling or an out of position picture.
So, do you guys have videos recorded for this kind of system already or do you convert video (downscale) for these Televisors? I was looking for some to download to try and started to believe I will have to create them myself.
Thanks,
FlyMario
There is software that will convert pictures and videos to NBTV audio and create a .wav or output directly to the sound card.
The club standard is 32 lines, 12.5 FPS with a (~175 uS) negative sync pulse on 31 of the 32 lines. The sync pulse allows a sync circuit to lock the disc to the correct line and frame rate. There are a number of different ways to do that.
Some people sync only once per frame and others sync every line. Some experimenters use dedicated PLL chips although I have been using an Atmega328 programmed in the arduino environment implementing a soft PLL and PID control.
The most well known program is Gary's Video2NBTV
I have been developing a new program called FreeNBTV since I wanted to be able to tune all the parameters. It is less stable and has a bigger learning curve than Gary's but it lets you adjust framerates, sync lengths and levels and a lot more. It also uses FFMPEG to read the video files so it will handle just about any format.
It is interesting to think people were adjusting the motor speed per line.
FlyMario wrote:I don't see the schematic on the site.
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