by aussie_bloke » Fri Jul 27, 2012 6:26 pm
G'day all.
In the past few weeks I have been working on and off in the background on another Nipkow disc televisor with a twist of course, this project I am working on is a multi-standard Nipkow disc televisor consisting of 3 spirals of holes (60, 32 and 30 line) and both horizontal and vertical scanning! This set should cover the set standards of NBTV, wide screen 32 line, John Logie Baird 30 line, 60 line horizontal. As for TeKaDe 30 line horizontal, I will have to make the motor somehow rotate clockwise to make it work.
For the disc I decided to use an LP record this time (no it's not a Kamahl record lol) and I drilled 60 holes on the outer region of the record, 32 holes in the middle region and 30 holes on the inner region. For the template I used Gary's DXFNipkow program. For the drill bit, I used a sewing needle so the holes can be small enough for good resolution and minimal overlap.
The motor to be used is that 1940s sewing machine motor as it has a nice vintage look and works quite nicely and it spins anti-clockwise, just need to figure out a suitable speed control for it and possible synchronisation would be great, will work that out later on. I've decided to belt drive the disc too instead of direct drive.
For the woodwork and cabinetry and other bits and pieces I have been doing some Steptoe & Son junk runs picking up useful items from curbside junk piles and have picked up a little wooden desk with drawer which I thought would make a great base/stand for this set. Also visited the local tips and picked up an old drawer which I think would be perfect to house the disc in. I also have picked up from the junk piles other great items including junked printers which gave me cogs and spindle rods and many other useful items, cupboard drawers which will come in handy for any cabinetry work for my projects, and picked up other useful pieces which will be great for the project and other projects.
Working on the drawer which will house the Nipkow disc record, I replaced the draw bottom with plywood as it had woodplanks that were curved up from age and weather, I cut out two rectangular sections in the plywood for the horizontal and vertical sets of LEDs and drilled a hole in the centre for the disc, I placed a plastic cog in the centre hole so the spindle rod can easily slip in and rotate with not too much friction.
The LED banks I used two plastic pieces from the plastic offcuts from one of the junked printers as bases to mount the LEDs on, I did some careful measurement and marking of where I am going to situate the LED clusters for each set of spirals and marked/drilled the holes in the plastic bases and ground the edges of the LEDs so I can mount them very close together. The resistors at the back are 100 ohms each driving 4 LEDs. I made the LED clusters a bit bigger than the scanned area to compensate for any slight miss-positioning of the LED bank sets. I am yet to make the hoods for them with the light diffusers but endeavor to do so soon, as suggested by Harry I will use plastic off a milk bottle as the diffuser and have an empty milk bottle ready to cut.
Next I was thinking about how I am going to mount the motor and was debating on whether to directly or indirectly drive the disc, I decided to indirectly drive the disc with a belt and spindle as it would be easier to mount the motor without too much precision with the motor's height position, plus I can easily change motors should it not work up to par. So I decided to have the disc mounted on a spindle rod which will be belt driven by the motor, for the rod I used a rod from a roller of on of the junked printers, cut a section of it which had a gear cog firmly stuck to it which I think will be great to glue the disc onto. I used another gear cog to mount into the centre hole on the drawer bottom so the spindle can freely rotate with minimal friction as previously mentioned. For the motor I made a wooden frame to mound it on plus a rear support at the top for the back end of the spindle which is an aluminum tube mounted in the wood cross beam at the top of the frame. I have mounted the frame to the desk using 4 long bolts and mounted the motor to the frame using the screw underneath and screws at the front.
Testing the belt drive, I have done a couple of tests with a couple of belts and the spindle successfully moves but the belts tend to slip and ride up and down the spindle rod shaft so I will have to mount a pulley cog onto the spindle. As for the friction, it's quite good at the front end due to the plastic cog but there is a fair bit of friction at the back end due to the slightly tilted aluminum cog and pull pressure from the belt, little teething troubles but I will work them out.
Anyhow the project is far from testing stage yet, much more to construct but it's coming along nicely so far!:D Here below are pictures of the construction progress of this multi-standard televisor:
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Last edited by
aussie_bloke on Sat Aug 04, 2012 1:33 pm, edited 2 times in total.