Compact Fire Drum

Forum for discussion of narrow-bandwidth mechanical television

Moderators: Steve Anderson, Dave Moll, Andrew Davie

Compact Fire Drum

Postby Robonz » Tue Sep 26, 2017 5:18 pm

So my first mechanical TV is built and I am still refining it but I have the urge to start a new design. Here is what I am thinking...

Make a drum that has either 32 or 60 leds on it. For simplicity I will describe the 32 line version. I would put 32 led's on a drum. To make it compact I would only have 8 segments, so a line of 4 led's every 45 degrees. The first line would have led's for line 1, 9, 17, 25. I would use some kind of mechanical divide by 4 to give one sync pulse per 4 revolutions of the drum. Only one set of led's would be driven at anytime. No adjacent led's would be driven at anytime of course. To do a 32 line with 4 revolutions per frame would require a speed of 750rpm x 4 = 3000rpm for a 12.5hz picture.

The signal would be done a bit like Harry's inductionvisor but multiplexed into 4 sets of led's to make the compact design. Each vertical frame would cover a full 45 degrees of the drum so the image could be quite large as compared to the drum size.

The big one is, can I manage a 3000 rpm drum say around 200mm diameter? Is this idea flawed? Are multiple light sources cheating the spirit of mechanical TV? Any ideas or comments?

Other things I would like to add to this would be:

Colour. can you have sound with colour, 3 channels?
I wonder if an Arduino can handle the bandwidth of colour and sound or 60 lines or both?

These are is my thoughts for now and I am not locked into anything. I will have some good resources over Christmas to put some energy into another mechanical TV. I have a second PCB from Andrew and would like to use this, as it is a great shortcut to completing a design. One thing is for sure I want to build another machine.

Cheers
Keith
User avatar
Robonz
Evil Genius
 
Posts: 142
Joined: Sat Aug 12, 2017 7:15 pm
Location: New Zealand

Re: Compact Fire Drum

Postby Andrew Davie » Tue Sep 26, 2017 11:33 pm

Robonz wrote:I wonder if an Arduino can handle the bandwidth of colour and sound or 60 lines or both?


Nope! Not even close. It's already pushing things; I had it (just) doing 44KHz CD-format files and even then I was out of processing time.
User avatar
Andrew Davie
Frankenstein was my uncle.
 
Posts: 1453
Joined: Wed Jan 24, 2007 4:42 pm
Location: Hobart, Tasmania, Australia

Re: Compact Fire Drum

Postby Harry Dalek » Wed Sep 27, 2017 2:10 pm

Andrew Davie wrote:
Robonz wrote:I wonder if an Arduino can handle the bandwidth of colour and sound or 60 lines or both?


Nope! Not even close. It's already pushing things; I had it (just) doing 44KHz CD-format files and even then I was out of processing time.


What about 3 Arduinos for each video colour channel ?

I would say on the motor speed i would use a pulley system so the dc motor can rotate the drum as fast as you can make the size of the pulley on the drum in fact you could make it with your tools the size of the drum i could do 60 line even on my converted dvd case holder i used as a drum many builds ago and its pulley was not that large ..but i was only using i think 8 slits for that drum you are using one for each line so your speed problem is not really there come to think of it .
if you go 2 drum monitor you will have a larger display to around the size of a small crt display ..going 60 line on a nipkow or higher just gets tiny..2 drum or disk monitors are not much harder the frame disk or drum is really no problem its the line drum that has to be spot on speed wise .
Would have to change things as far as the fire drum idea perhaps it could be used on the framing drum instead .
But it will be interesting to see it come about what ever you make .
Looks workable to me ...i have run many monitor just on manual control work out the automatic speed contol later if you want .
Last edited by Harry Dalek on Wed Sep 27, 2017 2:53 pm, edited 1 time in total.
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 3861
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

Re: Compact Fire Drum

Postby Robonz » Wed Sep 27, 2017 2:51 pm

Harry, I like that optimism. Reading through the forum I can see you have done many many experiments. (Harry Dalek 3432 posts!)

At the end of the day Andrew's board will happily do a 32 line black and white fire drum which is maybe where I should start, should I go down this path. The academic discussion is great though.

I think if I wanted colour with audio I would probably want a 4 channel wav file. One channel for Red, Green, Blue and sound. The image could then be processed to two colour if that was the desired signal. This would be the hard part for me is AVI to RBG+audio wav converter. Is there anything around that does something like this? I have looked up 4 channel wav files and they are no harder to do than 2 channels. Also in the digital domain they are not bandwidth limited like audio amplifiers.

I looked at some Arduino's and the "Maple Mini" http://wiki.stm32duino.com/index.php?title=Maple_Mini at a glance should easily do the trick but porting Andrews code would probably be very laboursome and problematic as the architecture is totally different.

Many hoops to jump through for sure.

I was thinking at this point, if I went to all this trouble I may as well light every LED on every rotation, then you would have full RGB colour at 25Hz with a drum speed of 1500 rpm. That would be pretty awesome.

Still contemplating....
Keith
User avatar
Robonz
Evil Genius
 
Posts: 142
Joined: Sat Aug 12, 2017 7:15 pm
Location: New Zealand

Re: Compact Fire Drum

Postby Harry Dalek » Wed Sep 27, 2017 3:57 pm

Robonz wrote:Harry, I like that optimism. Reading through the forum I can see you have done many many experiments. (Harry Dalek 3432 posts!)


Yes its a very interesting hobby to me ,many ways to do the same thing always learning ,at the moment i am more of the electronics side of the hobby and on the camera side of things as well mainly because its harder and i need to learn some things here ....a goal in the future is a higher line rate mechanical camera but leaning how to do this easier way first so i have some thing to display to when i do try to make one .

At the end of the day Andrew's board will happily do a 32 line black and white fire drum which is maybe where I should start, should I go down this path. The academic discussion is great though.


IF you stick to the original fire drum idea you could still use he 3 colour led just in case you want to convert later but B?w is still good .

I think if I wanted colour with audio I would probably want a 4 channel wav file. One channel for Red, Green, Blue and sound. The image could then be processed to two colour if that was the desired signal. This would be the hard part for me is AVI to RBG+audio wav converter. Is there anything around that does something like this? I have looked up 4 channel wav files and they are no harder to do than 2 channels. Also in the digital domain they are not bandwidth limited like audio amplifiers.


Yes that is a problem what about Garys 15 line 3 colour frame sequential colour ,,,,

for a different B/w system to your design make your own system use smeezekitty 's on off topic new freenbtv software works well ...does not have to be 32 line to be NBTV just a different standard why not !

I looked at some Arduino's and the "Maple Mini" http://wiki.stm32duino.com/index.php?title=Maple_Mini at a glance should easily do the trick but porting Andrews code would probably be very laboursome and problematic as the architecture is totally different.


Again it does not have to be a mini computer controlling the monitor old fashion ways can still work but not as good seeing you and Andrews monitors of late .

Many hoops to jump through for sure.


Pretty much what ever you can think of that works and you think you can do it its always why not try .

I was thinking at this point, if I went to all this trouble I may as well light every LED on every rotation, then you would have full RGB colour at 25Hz with a drum speed of 1500 rpm. That would be pretty awesome.

Still contemplating....
Keith


Keith that does sound good ,i will be watching seeing it evolve ..i have not really tried colour i like it but i also like classic B/W .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 3861
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

Re: Compact Fire Drum

Postby Robonz » Wed Sep 27, 2017 8:16 pm

Hi Harry

Thanks for such a detailed response. I will be watching Smeezekitty 's progress. It sounds like it could be quite powerful when completed. Andrew has requested NBTV8 format too which would be very useful for people working with digital videos.

Harry: I have not really tried colour i like it but i also like classic B/W


Yes, that is one of the main issues I have with this design I am contemplating. It kind of misses a couple of the items that give these machines nostalgia. 1) Being not just colour but full RGB, 2) Using led's (pixels) instead of one light source seems to make it lose the retro look and feel. One thing about the TV I built is it has a nice retro historic look that I did not try hard to do. It is a result of the Nipkow style of machine it is.

I guess this is a reason why I am still contemplating my next machine. e.g. I really like the Holtzman compact drum. It has all the retro appeal with the single light source and full mechanical scan. I do like the digital signal source e.g.SD card as the video source as it makes the units complete and portable.

Yes its a very interesting hobby to me ,many ways to do the same thing always learning ,at the moment i am more of the electronics side of the hobby and on the camera side of things as well mainly because its harder and i need to learn some things here


Its quite interesting you like the challenge of the electronics. For me the mechanical part is the interesting challenge. The electronics is the bit I find fairly easy. I used to build a lot of robots and my fast method of wiring was wire wrap. Here is an example. The bottom of the board is dead clean. I just solder a row of header pins down the side of a chip and wire wrap away. very fast, clean and reliable.
[img]IMG_3165.JPG[/img]


Cheers
Keith
Attachments
IMG_3165.JPG
User avatar
Robonz
Evil Genius
 
Posts: 142
Joined: Sat Aug 12, 2017 7:15 pm
Location: New Zealand

Re: Compact Fire Drum

Postby Harry Dalek » Thu Sep 28, 2017 12:14 am

Robonz wrote:Hi Harry

Thanks for such a detailed response. I will be watching Smeezekitty 's progress. It sounds like it could be quite powerful when completed. Andrew has requested NBTV8 format too which would be very useful for people working with digital videos.


It seems to work well really useful testing a monitor with a different line rate frame rate to the norm ,a viewer that can do the same we have it made great tool for testing gear.


Yes, that is one of the main issues I have with this design I am contemplating. It kind of misses a couple of the items that give these machines nostalgia. 1) Being not just colour but full RGB, 2) Using led's (pixels) instead of one light source seems to make it lose the retro look and feel. One thing about the TV I built is it has a nice retro historic look that I did not try hard to do. It is a result of the Nipkow style of machine it is.


IT is a hard one how far to go before its something else ,using he micro computer does show how well it can work pushing the nipkow into this century,colour does make it look great but it hasn't got me to make one yet ...may be a colour wheel i like that idea .

I guess this is a reason why I am still contemplating my next machine. e.g. I really like the Holtzman compact drum. It has all the retro appeal with the single light source and full mechanical scan. I do like the digital signal source e.g.SD card as the video source as it makes the units complete and portable.


The framing drum could be a rotating light powered and modulated by induction or as is and still be powered by induction ...
I tried 2 of this type of monitor its really quite easy to get going no harder than a nipkow but you have 2 advantages first a large screen size second it is multi system ...line drum speed is same as if you made a nipkow but the framing drum speed is not critical as far as a viewing the image ....change it it from the correct frame rate it looks like a zoom control on the image mage it bigger or smaller ..i don't think i tried this on a moving image so that i can't say ..i still have both beasts must be very dusty these days .
I loved Holtzman's mechanical switching for the stepper motor to move the framing drum great idea.


Its quite interesting you like the challenge of the electronics. For me the mechanical part is the interesting challenge. The electronics is the bit I find fairly easy. I used to build a lot of robots and my fast method of wiring was wire wrap. Here is an example. The bottom of the board is dead clean. I just solder a row of header pins down the side of a chip and wire wrap away. very fast, clean and reliable.
[img]IMG_3165.JPG[/img]


Cheers
Keith
[/quote]

There's so much to learn in this hobby i will never know it all but i will try what ever i can that interests me till i drop ,Yes the mechanical side is hard i repurpose stuff so that's easier not have the tools to make some thing ..the electronics side i am ok at copying and reusing ideas for a different purpose but not great at making some thing from scratch ....wire wrapping i can't say i have tried apart from twisting wires before i had a soldering iron :wink:
On the monitor again have a think at what you want it to do there are many different ways to make one from mirrors to lens slits holes leds for me on the mechanical side of things ...i liked the Holtzman monitor the best which came from a inventor from the 30s think he's drums were all geared must of been very noisy come to think of it so was mine ! hes a little video me playing around with it ..had problems drum made from old dvd holder so would warp at speed and pulley system rattles a bit :roll:

Attachments
Picture 2203.avi
drum monitor adjusting framing control
(8.79 MiB) Downloaded 57 times
Picture 2203.mp4
(10.84 MiB) Downloaded 302 times
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 3861
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia

Re: Compact Fire Drum

Postby Robonz » Thu Sep 28, 2017 3:49 pm

Hi Harry

That's a nice effort on your twin drum monitor. They look really hard to build. When you can't support both sides of a drum its very hard to not let it wobble. I had this idea you could use a really big bearing on both sides, with say a 50mm id and then you could poke supports and wiring etc through the bearing to get stuff mounted inside. This would make it really stable but more difficult to work on.

I totally understand your feelings on a mechanical colour wheel being so much more attractive than an RGB led. I feel the same way. The more our home made devices match the period, the more nostalgia/authenticity they seem to have which is what got me into this in the first place. Vintage electronics and machines are so fascinating. I have been tempted to build steam engines too.

I think 2 colour screens still have that vintage feel as they have that old school colour which adds to the authenticity.

Andrew has mentioned I might like to build a mirror screw and yes, I think I would like to build one. I am looking at that design now too. Do you think 1mm thick mirrors (i.e. not surface mirrors) would be good? I have some plastic ones here I can laser cut. The other question is a double helix looks good so the rpm can be 750 rpm instead of 1500 rpm if I understand thing right. Is a double helix hard or easier?

Cheers
Keith
User avatar
Robonz
Evil Genius
 
Posts: 142
Joined: Sat Aug 12, 2017 7:15 pm
Location: New Zealand

Re: Compact Fire Drum

Postby Harry Dalek » Fri Sep 29, 2017 10:52 am

Robonz wrote:Hi Harry

That's a nice effort on your twin drum monitor.


It really needs a rebuild of the main drum a tin drum a large can with sections cut out then a plastic cover with the line slits would be better for any thing over 32 lines or some like that centrifugal force when at high speed cause's warping.


They look really hard to build.


The little framing drum is the hard one would be a lot easier with 2 disks if you didn't worry about the curvature of the line result with is a lot more on a monitor like this using disks.
i always thought this idea has a lot less problems ..

When you can't support both sides of a drum its very hard to not let it wobble. I had this idea you could use a really big bearing on both sides, with say a 50mm id and then you could poke supports and wiring etc through the bearing to get stuff mounted inside. This would make it really stable but more difficult to work on.


What i used is a thin plastic and the high speeds needed the slight warping causes the line to have a sine wave look 32 line its fine not to bad at 48 but 60 not
Yes that's a good idea the open side would gain from your idea for sure ,the wiring in the way was always a problem trying this ,it would have to be custom made bit beyond my skills ...

I totally understand your feelings on a mechanical colour wheel being so much more attractive than an RGB led. I feel the same way. The more our home made devices match the period, the more nostalgia/authenticity they seem to have which is what got me into this in the first place. Vintage electronics and machines are so fascinating. I have been tempted to build steam engines too.
I think 2 colour screens still have that vintage feel as they have that old school colour which adds to the authenticity.


Mechanical colour is more interesting to me but leds do make it very easier ....more the reason there are so many led colour monitors than colour wheel which i can't say i can think of one NBTV version !
2 colour monitor would be good too ,colour wheels are a way of changing the b/w monitor to colour just sticking it in front and syncing it .



Andrew has mentioned I might like to build a mirror screw and yes, I think I would like to build one. I am looking at that design now too. Do you think 1mm thick mirrors (i.e. not surface mirrors) would be good? I have some plastic ones here I can laser cut. The other question is a double helix looks good so the rpm can be 750 rpm instead of 1500 rpm if I understand thing right. Is a double helix hard or easier?

Cheers
Keith
[/quote]
I think that would work a good idea i always thought of the plastic mirrors but i have no way to cut them correctly ,i haven't really made a mirror screw so the difference in making those i can't say ,the mirror you have cut i do know the gluing to a flat surface might be a problem as the glue can cause it to change the angle of reflection some thing i have always found trying to mount mirrors .
The electromagnetic spectrum has no theoretical limit at either end. If all the mass/energy in the Universe is considered a 'limit', then that would be the only real theoretical limit to the maximum frequency attainable.
User avatar
Harry Dalek
"Fester! Don't do that to 'Thing'"
 
Posts: 3861
Joined: Fri Sep 26, 2008 4:58 pm
Location: Australia


Return to Mechanical NBTV

Who is online

Users browsing this forum: No registered users and 1 guest

cron