** Build your own TV **

I have made up some scanning disk bearing/pulley assemblies from existing VCR assemblies, just as described in the second installment. The ball bearing assembly includes a pulley and a scanning disk hub, with a choice for use with a 1/4", 3/16" or a 6 mm center hole. These are available directly from me. Peter Yanczer

Fourth Installment

Materials you will need for this installment

* 24 Hi-Brightness orange or white LEDs.

* 3 Dual-in-line, 16 pin wire wrap I.C. sockets

* 1/16" Felt material

* Disk drive DC motor. See text.

* Misc small pieces, aluminum and wood.

The next thing to do is to build the mountings for the bearing/pulley assembly and the disk drive motor. Following that, you can build the parts for the LED array. I'll be showing you one or two ways to do these things, but you should feel free to do them another way, your way, if you can accomplish the same results. All of these items will be attached to the top rear cover of the cabinet later. Here is a drawing to help you see how these mounts are made up. The materials for each of these can be metal, wood or plastic. Use what you feel most comfortable working with.

The motor to be used here is of the sort found in some of the early 8-track recorders. However, some motors also include an internal constant speed controller that must be disabled before use. These motors are also usually a bit larger and/or more powerful than those used in cassette decks, making them the better choice. However, some of the cassette motors will work. You need to try them before you make their installation permanent.

The motors that I use are ball bearing types. They allow higher belt tension to be used, resulting in less slip and therefore more stable operation. I have a small quantity available for sale at approximately 1/3 of their original cost. These motors are new and American made for a computer application that has been phased out.

They measure approximately 1 1/2" diameter and are 2 1/2" long. They include a pulley suitable for a flat belt or an "O" ring belt. These are available directly from me. PY

Item #1 of the drawing is a motor mount of the sort shown in the earlier photos. It was made of 2 pieces of wood about 3/4" x 1" x 3". The center hole was made by clamping the pieces together and using a hole saw in a drill press. Bore in from one side and then the other. The hole is made slightly larger than the motor diameter. A cushion of thin rubber tape should be wrapped around the motor where it contacts the mount. Masking tape could also be used here. Separate screws can be used to clamp the mount together or if you have some long enough, they can also hold the motor and mount assembly to the top rear cover. However, don't install the mount yet. That will be done later.

In the drawing, items #2 and #3 show a more simple and commonly used form of motor mount. It is simply a strap of aluminum, steel or nylon. The strap is wrapped around the motor with two or more screws at the ends holding it to the rear top cover. The width of the strap is about the length of the motor case and the length of the strap is chosen so that it will go around the motor as shown in the drawing. A rubber cushion on the motor would be useful here too.

Items #4 and #5 are two types of bearing/pulley assembly supports. The first is fabricated out of wood or metal and the other out of metal. The mount measures approximately 4" high and it is 3" wide.The center of the scanning disk should be located about 2 3/8" above the top surface of the rear cover. Therefore, the clearance hole for the bearing/pulley assembly should be located so as to accomplish this.

The clearance hole diameter will depend the particular bearing assembly you have, but generally a 1" hole diameter will do. Center the outer flange of the assembly on the mount, being careful to retain the 2 3/8" dimension to the base and mark at least 3 locations for screws to pass through the flange and into the mount. If the mount is wood, you can use wood screws, but nuts and bolts are preferable. The minimum screw size should be a #4 x 40 size. Enlarge or add additional holes in the flange if necessary. With a metal mount, use nuts and bolts. This whole assembly will be fastened to the top of the rear cover with two #6 x 32 nuts and bolts.

The LED array consists of 24 high-intensity orange LEDs that illuminate the back side of the scanning disk, providing the light that forms the image. Their orange color provides a close simulation of the color of the original neon Kino-Lamps. If you should choose white LEDs, the image will show more contrast and for some, be more pleasing to the eye. The LEDs effectively operate in parallel. The array requires a means of combining the 24 small points of light from the LEDs into one homogeneous large area light source. A ground glass square or similar plastic material helps to accomplish this. This source of light is larger than the image, so an image mask to control the size and shape of the image is made a part of this light source. Finally, since the mask is immediately behind the scanning disk. It may therefore be contacted by the rotating disk, possibly damaging the disk or the mask. To prevent this, a layer of felt cushioning material is cemented to the front surface of the mask. Should the disk contact the felt, there will be no damage.

The LED assembly shown in the previous installment photos, looks a bit different than the one described here. In the one pictured, the LEDs are in its base, pointed upward towards a 45 degree inclined mirror. The light travels from there to the ground glass screen which includes the mask and felt cushion. The whole assembly is contained in a section of square aluminum tubing. This array is not the one described here because it is more difficult to construct. A more simple, yet effective design follows.

A convenient way to hold the 24 LEDs in the array is to use three 16 pin dual in line I.C. sockets of the wire wrap variety. Each socket will hold 8 LEDs. Item #6 in the drawing, shows a means to position three sockets so as to approximate the shape of the image. The support for the sockets can be a 2 1/2" X 3 1/2" piece of this plywood or better yet, a piece of perforated "vector board" available at electronic supply stores. The sockets can be held in place with contact cement or small dabs of "crazy glue".

The mask, item #7, is best made of aluminum about .040" to .060" thick. The opening for the image is rectangular, about 7/8" wide and 1 1/8" high. The center of this opening, like the center of the LED socket array, is located 2 3/8" above the base.

Item #8 in the drawing shows the overall location of the parts of the array. The LEDs are located about one inch from the ground glass which is cemented to the back of the mask. The front of the mask has four 1/2" wide strips of felt cemented around the opening in the mask. Spray on contact cement, (Scotch #77) is good for this application.

Do not attach the array parts to the rear top cover yet. The array and motor will be installed after the scanning disk bearing/pulley assembly is in place.

End, Installment Four

Peter Yanczer

On to installment #Five

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