The source of inspiration for my device is the ‘Chromola’, an instrument that Preston S. Millar created to provide colour light accompaniment to Alexander Scriabin’s ‘Prometeus: Poem of Fire’, a symphony premiered at Carnegie Hall on 21 March 1915. The work was written for piano, orchestra and coloured lights. Mr Scriabin wrote the ‘lights’ part in the work’s score where he ‘mapped’ notes into colours. Lights were projected on a screen installed in face of the audience.

I made a palette that can ‘paint’ a note a colour of the rainbow; the screen is a small cylinder installed on the palette itself. The correspondence of colours and notes is as follows:

Red C, Orange D, Yellow E, Green F, Blue G, Indigo A, Violet B.

The red colour has the lowest frequency in the light spectrum, as well as the note C has the lowest frequency in an octave. Then, frequencies of both lights and notes keep increasing to achieve violet and B. Dieses are obtained by pressing two neighbour keys at the same time, for example, (Red + Orange) gives the colour corresponding to C#.

Supplies

Materials

Plywood 4 mm thick

Thin tin

Copper clad textolite (or similar material)

Steel rod about 1.5 mm diameter

Styrofoam sheet

Paper, transparent, half-transparent and opaque

Aluminum foil

Foam paper

Thick cloth

Hardwood pins

Bulbs T5-286

Wires

Pushbuttons

Power adapter 12V (AC/DC) that can supply current up to 300 mA

Small screws

Acrylic paints of the rainbow colours

Colourless varnish

Glue

Tools

Hand jigsaw

Soldering gun with solder

Exacto knife

Small tin snips

Scissors

Drill with drilling bits

Flat nose pliers

Screwdriver

Metal file

Sandpaper

Brush

Drawing tools

Step 1: Palette's Body

The patterns attached to the step should be used to make the bottom and top plates of the palette, as well as the spacer. I would suggest the following technique:

- print the right and left patterns on an A4 sheet each. The assembled pattern is supposed to be inscribed into a 290 x 240 mm rectangle, this gives you an idea about how to scale the images before printing

- join (using glue) the patterns, so the both outlines coincide. Copy the entire external outline and the outline of the spacer on a sheet of transparent paper of appropriate size

- transfer the external outline onto two plywood plates of appropriate size; transfer the outline of the spacer onto a plywood plate of appropriate size. Mark the centres of the openings in the future upper plate; draw the outlines of the openings for the projector (D80 mm) and the keys (D30 mm)

- cut the plates and spacer using a hand jigsaw (I used one, you are free to choose your tool); cut the openings in the upper plate

- glue the spacer onto the bottom plate

- drill 4 holes D8 mm in the subassembly ‘plate-spacer’; glue into the holes 4 hardwood inserts (diameter 8 mm, height 8 mm. I cut a pin used in IKEA furniture to make them); drill in the centres of the inserts through holes for small screws (the holes’ diameters depend on the screws’ size)

- mark the centres for the screws in the upper plate using the through holes in the bottom plate as template. Drill holes for screws (diameter depends on the screws used)

The upper and lateral surfaces of the palette are painted white, the bottom could be unpainted. Two pads made of thick cloth are glued onto the bottom of the palette; you are free to choose their form.

Three other elements are necessary:

- a shim made of thin foam paper. It will repeat the outline of the spacer; this element assures that keys touch push button only when pressed by the performer

- a pad made of thin plastic (I used a piece of a shopping bag); the keys will be fixed on it, the pad being fixed to the upper plate

- a pad made of copper clad textolite or similar material. The circuit wiring and the wires from the power jack will be soldered to this pad.

Step 2: Projector

All parts (except the pads for bulbs) of the projector are made of thin tin (about 0.5 mm thick); the pads are made of copper clad textolite. Pictures attached to the step indicate dimensions that are essential for making the projector’s components which could be cut using small tin snips.

The projector consists of 7 small truncated pyramids (the pyramid net is attached to the step) soldered onto the upper ring. You cut a pyramid net, ply it using flat nose pliers and solder the joint line; two solder point would suffice. After all pyramids are ready, you solder them onto the upper ring; a solder point on each pyramid’s side would suffice.

The upper ring has 7 holes for the bulbs, the angle between the centres of the holes being 51.43 degrees (360 divided by 7); however, 51.5 would be a good approximation. The ring also has 3 small holes (D1.5 mm) where 3 pins (made of thick steel or copper wire) will be soldered. These pins fix the ring onto the bottom ring which also has small holes for these pins. The distance between the two rings should be 8 mm. That’s how I proceeded:

- install 3 wooden spacers 8 mm high between the rings

- insert 3 pieces of thick wire, previously tinned, into the appropriate holes in the rings. These pieces should be about 12 mm long

- solder the pins to the rings

- remove the spacers

The bottom ring has 4 legs which serve to fix the projector onto the bottom plate. Small textolite pads are glued onto the ring exactly under the holes for the bulbs. Both the bulbs’ leads and the wiring will be soldered to these pads.

Step 3: Keys

I cut 7 circles from plywood; then I drew 7 circles in Autocad and painted them appropriately using the command ‘Gradient’. After that I printed, cut and glued them onto the plywood circles; then I put colourless varnish on the circles to protect the paint. Thus, I assured uniform painting of the surface. The printed circles are attached to the step, so you can use them,too; otherwise, you can just paint them.

Step 4: Filter

The filter consists of a disc made of thin transparent plastic (about 1 mm thick) and a lateral side also made of thin transparent plastic (about 0.5 mm thick, I used a piece of a plastic bottle).

The disc would be painted from both sides in the rainbow colours, there are 7 sectors on the disc each corresponding to a colour; the angle of a sector should be (exactly) 51.43 degrees, but 51.5 would be a good approximation.

The lateral side is glued onto the disc’s edge, and a stripe of thin aluminum foil is glued onto the side. This side holds the filter in place.

Step 5: Screen

You observe the following components in the attached picture:

A - a circle D86 mm cut from plywood. There are 3 holes D8 mm to assure that air passes through the screen to avoid its heating; however, you are free to choose the diameter, the number and the positioning of these holes. The circle’s bottom is covered with aluminum foil to reflect the lights coming from the projector. The circle is glued into the component B so the circle is flush with the upper edge of B

B - a fragment of plastic bottle (diameter 86 mm, height 130 mm) covered with rice paper or another kind of half transparent paper. This is the cylindric screen

C - a ring made of a 15 mm styrofoam sheet that was available. (The ring’s outer diameter is 100 mm, the inner diameter - 86 mm). I cut the ring using an exacto knife, gave it the final shape using sandpaper and glued it onto the cylinder B, so that the ring’s bottom be flush with the cylinder’s bottom edge

After the ring is fixed on the cylinder, an opening for the jack should be made in the subassembly.

The assembled screen will be glued during the final assembly onto the upper plate coaxially with the opening for the projector.

Step 6: Circuit and Final Assembly

The circuit consists of 7 bulbs T5-286 (they are used in cars’ dashboards), 7 small push-buttons, a jack to connect external power supply, wires. This bulb needs 12V and consumes 1.2W of energy.

I used incandescent bulbs which: a) were available at my workshop; b) allow using both AC and DC power. A LED-version of these bulbs could be surely used, the power supply being only DC in that case.

The current which a bulb consumes is 100 mA, two bulbs at the same time (when you play dieses) consume 200 mA; that’s why I suggest using an adapter that can supply up to 300 mA; thus, a power reserve is assured.

The jack is glued onto the upper plate. Wires from the jack are soldered during the final assembly to the pad fixed on the bottom plate.

I used the following technique to perform the final assembly:

- glue thin plastic film onto the upper plate behind the openings for the keys

- glue the keys to the film

- glue the screen onto the upper plate

- glue the foam paper shim onto the spacer. I needed that shim to provide a small distance between the push buttons and the keys, so the button is pushed only when the key is pressed by the performer

- fix the projector on the bottom plate using small wood screws

- solder the wires from the jack to the pad on the bottom plate

- put the upper plate onto the bottom plate and fix it using small wood screws