Elenco Upgrade Kit SC500 to SC750 - Manual (Page 19)

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Watch the LED’s (D1 & D2) as you press or release
the press switch (S2). The red LED (D1) lights briefly
just as you press the press switch and the green LED
(D2) lights briefly just after you release it, but neither
lights while you hold the press switch down. Why?
When you press the press switch, a surge of current
from the battery charges a magnetic field in the
transformer (T1), which stays constant as the press
switch is held down. Charging the magnetic field
induces an opposing current on the other side of the
transformer, which lights the red LED until the
magnetic fields stabilize.
When you release the press switch (removing the
current from the battery), the magnetic field
discharges. Initially the transformer tries to maintain
the magnetic field by inducing a current on the other
side, which lights the green LED until the resistor (R1)
absorbs the remaining energy.
Note that this project is different from the Antenna
Storing Energy project because there is a magnetic
connection across the transformer, not an electrical
connection.
Modify project #532 by replacing
the transformer (T1) with the relay
(S3), position it with the 3-snap
sides to top and right (as in project
#341).
Hold down the press switch (S2)
and then watch the LED (D1) as
you release the press switch. The
LED lights briefly but only after the
batteries (B1) are disconnected
from the circuit.
The relay has a coil similar to the
one in the transformer, and stores
energy in the same way.
Relay Storing
Energy
Project #532
OBJECTIVE: To show that the transformer stores electrical
energy.
Transformer Storing Energy
Project #534
OBJECTIVE: To show how the transformer works.
Transformer Lights
Hold down the press switch (S2) and then watch the LED (D1) as you
release the press switch. The LED lights briefly but only after the
batteries (B1) are disconnected from the circuit.
This circuit is similar to the Antenna Storing Energy project, and shows
how the coils in the transformer (T1) also store energy in magnetic
fields. When the press switch is released, this energy creates a brief
current through the LED.
Project #533
This circuit is based
on one suggested by
Mike D. of
Woodhaven, NY.
OBJECTIVE: To show that the
relay stores energy.
To learn more about how circuits work, visit www.snapcircuits.net or page 85 to find out about our Student Guides.