Elenco Basic Electronic Experiments - Manual (Page 55)

EXPERIMENT #38: ELECTRONIC KEYBOARD
This experiment will use the (almost) same circuit as the last one, so there is no schematic or Wiring Checklist. The only
difference is that you will draw a new shape.
As before, take a pencil (No. 2 lead is best but other types will also work), SHARPEN IT again, and fill in the shape you
see below. For best results, SHARPEN IT again, place a hard flat surface between this page and the rest of this
booklet while you are drawing. Press hard (but don’t rip the paper). Fill in each several times to be sure you have a
thick, even layer of pencil lead, and try to avoid going out of the boundaries. Where the shape is just a line, draw a
thick line and go over it several times. The black ink in this manual is an insulator just like paper, so you have to write
over it with your pencil.
Take one loose wire and touch it to the left circle. Take the other loose wire and touch it to each of the other circles. The
various circles produce different pitches in the sound, like notes. Since the circles are like keys on a piano, you now have
an electronic keyboard! See what kind of music you can play with it. Note: you may get better electrical contact between
the wires and the drawings if you wet the wires with a few drops of water or saliva.
Now take one loose wire and touch it to the right circle (#11). Take the other wire and touch it to the circles next to the
numbers shown below, in order:
7 - 5 - 1 - 5 - 7 - 7 - 7
5 - 5 - 5
7 - 7 - 7
7 - 5 - 1 - 5 - 7 - 7 - 7 - 7 - 5 - 5 - 7 - 5 - 1
Do you recognize this nursery rhyme? It is “Mary Had a Little Lamb”.
By now you see that you can draw any shape you like and make electronic sounds with it. Experiment on your own as
much as you like. The circuit here is nearly the same as for Experiment 29 (Electronic Sound), so you can use the notes
you took there to estimate what the resistance is at various points along your keyboard or any other shapes you make.
Be sure to wash your hands after this test.
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Shape to be drawn.
Use a SHARP No. 2 pencil, draw on a
hard surface, press hard and fill in
several times for best results.