Ben Heck’s Mechanical Television Part 2 Episode -- Episode 233

I did a similar project back in the 80's for a high school science fair project... and again a few years later during a slow semester at college.

Anyway, a few notes on how to salvage something cool from failure:

- The disk most synchronized with your display disk is... the display disk itself.  Those holes go all the way around so use the bottom of the record for image capture and the top for display.  One record, one motor, you can spin it by hand if you like. (yes, the image is flipped and mirrored)

- For lots of fun you really only need to build the display unit, and it can have a constant light source always on.  You can make an image by putting another disk between the light source and the spinning record.  That intermediate disk has slots cut in it so it turns the light source on and off.  This intermediate disk doesn't have to be the same radius... it just has to have slots cut in it so it chops up the light.  I made a whole set if disks, each was cut to show a different image (a stick man, a triangle, letters, etc).  Synchronization of the slot disk was done manually by the person viewing the image by using a controller from a slot car race track.  And the slot disk also doesn't have to be intermediate between the light and the spinning hole disk (it wasn't in my science fair project).  You can place it in front of the record and look through it.  For a quick approximation just wag your fingers back and forth in front of the record while it is spinning and there is a constant light source behind it.

- My college version used an array of LEDs for the light source (the brightest red ones that Radio Shack had in 1993).  They were controlled by a parallel port hooked up to a  486 system running a version of linux most of you might not recognize today.  Relatively simple software turned the led array on and off  (as a whole) to produce an image.  Synchronization was manual, but the computer could keep pretty good time (even from a user mode application) and the motor would spin at a fairly regular rate.  The software had a couple keys you could press to speed up or slow down the timing.  Animation was just a few lines of code more... The ladies really swooned when they saw that red pixelated stick man do jumping jacks.  Had I not gotten a job and started life I might have eventually gotten Doom to show up on the 'display'.

-Lastly, if you really insist on the camera portion (don't) it's better to put the image onto the surface of the scanning disk via a lens rather than projecting a flying dot and sit in the dark.  So, light your subject as brightly as possible (the sun makes a nice subject), put a cracker jack plastic lens in front of the scanning disk and focus it on the disk.  Put another lens behind the disk then the photo diode behind that. The holes slice across the image from the lens and the whole thing works... sort of.  But... just stick with the viewer and make a mechanical computer monitor or a mechanical video disk player.

I did a similar project back in the 80's for a high school science fair project... and again a few years later during a slow semester at college.

Anyway, a few notes on how to salvage something cool from failure:

- The disk most synchronized with your display disk is... the display disk itself.  Those holes go all the way around so use the bottom of the record for image capture and the top for display.  One record, one motor, you can spin it by hand if you like. (yes, the image is flipped and mirrored)

- For lots of fun you really only need to build the display unit, and it can have a constant light source always on.  You can make an image by putting another disk between the light source and the spinning record.  That intermediate disk has slots cut in it so it turns the light source on and off.  This intermediate disk doesn't have to be the same radius... it just has to have slots cut in it so it chops up the light.  I made a whole set if disks, each was cut to show a different image (a stick man, a triangle, letters, etc).  Synchronization of the slot disk was done manually by the person viewing the image by using a controller from a slot car race track.  And the slot disk also doesn't have to be intermediate between the light and the spinning hole disk (it wasn't in my science fair project).  You can place it in front of the record and look through it.  For a quick approximation just wag your fingers back and forth in front of the record while it is spinning and there is a constant light source behind it.

- My college version used an array of LEDs for the light source (the brightest red ones that Radio Shack had in 1993).  They were controlled by a parallel port hooked up to a  486 system running a version of linux most of you might not recognize today.  Relatively simple software turned the led array on and off  (as a whole) to produce an image.  Synchronization was manual, but the computer could keep pretty good time (even from a user mode application) and the motor would spin at a fairly regular rate.  The software had a couple keys you could press to speed up or slow down the timing.  Animation was just a few lines of code more... The ladies really swooned when they saw that red pixelated stick man do jumping jacks.  Had I not gotten a job and started life I might have eventually gotten Doom to show up on the 'display'.

-Lastly, if you really insist on the camera portion (don't) it's better to put the image onto the surface of the scanning disk via a lens rather than projecting a flying dot and sit in the dark.  So, light your subject as brightly as possible (the sun makes a nice subject), put a cracker jack plastic lens in front of the scanning disk and focus it on the disk.  Put another lens behind the disk then the photo diode behind that. The holes slice across the image from the lens and the whole thing works... sort of.  But... just stick with the viewer and make a mechanical computer monitor or a mechanical video disk player.