The two angle brackets on the side of the TERC VHS-1 allow
you to point the instrument directly at the Sun.
When you point the front end of the TERC VHS-1 toward the
Sun, sunlight will enter the case through the sunlight port.
Sunlight will also shine through the hole in the angle bracket
closest to the end of the case. Your goal: Make sure that when
the beam of sunlight from the sunlight port is centered directly
over the detector, the beam passing through the front angle
bracket always strikes a specific position on the lower bracket
which we will call the Sun Target.
Begin by placing a self-adhesive white label about the size
of a postage stamp on the rear angle bracket (the one closest to
the 2 terminals). This label is the Sun Target. Then take the
TERC-VHS-1 outdoors or to a clean window through which the Sun is
visible and follow these steps:
- Open the case and point the sunlight port toward the Sun. As
you move the case in various directions, the beam of sunlight
passing through the sunlight port will form a bright circle of
light on whatever it strikes inside the case.
- Carefully adjust the position of the case until the circle of
sunlight falls directly over the detector. You should then see a
bright circle of sunlight on the paper label stuck to the rear
- Use a pencil to mark a small dot on the label at the center of
the circle of sunlight. Be sure to hold the VHS-1 steady while
marking the label. It's best if a friend holds the case and makes
sure the circle of sunlight is centered over the detector while
you mark the Sun Target.
- Close the VHS case, connect a volt meter to the output
terminals, and turn the power switches on the voltmeter and the
TERC VHS-1 to the ON position.
- Point the TERC VHS-1 toward the Sun until the Sun Target is
centered in a circle of sunlight. Now watch the volt meter
readout while slowly moving the circle of sunlight around the Sun
Target. The voltage will jump around as you move the instrument.
If the sky is clear, you will notice that there is a point at
which the voltage is relatively stable and higher than at other
points. If the first mark you made on the Sun Target is not
centered in the spot of sunlight, make a second, darker mark in
the center of the circle of sunlight when the voltage reaches its
highest point. Again, it helps to have a friend hold the
instrument while you make the mark.