Elenco Snap Circuits Motion - Manual (Page 80)

Insert some of the cardboard figures into the 3 slots on the
edge of the merry-go-round base. Build this circuit and mount
the merry-go-round base onto the shaft on the geared motor
(GM).
Set the lever on the adjustable resistor (RV2) to the top. Turn
on the slide switch (S1), and use the lever on the adjustable
resistor to set the brightness of the red/yellow bicolor LED
(D10) and the speed of the merry-go-round base.
The merry-go-round will only spin for a small portion of RV2’s
adjustment range. If it does not spin even at the top RV2
setting then give it a gentle push clockwise to get started.
This circuit uses the NPN transistor
(Q2) and adjustable resistor (RV2) to
control the speed of the geared motor
(GM). A small electric current into the
transistor through RV2 and the LED
(D10) controls a larger current into the
transistor through the geared motor.
RV2 cannot be used to control the
geared motor directly, because its high
resistance would prevent the geared
motor from operating.
Project 164 Transistor Control
Build the circuit, turn on the slide switch
(S1), and set the switcher (S6) to the left or
right to control the light motor (M7).
Project 165 Reversible Motor Project 166
Slow
Reversible
Motor
Use the preceding circuit, but
replace one of the battery holders
(B1) with a 3-snap wire. Now the
motor spins slower and the lights
are dimmer.
-79-
In the light motor (M7), the motor spins in
both directions but the LED light circuit only
works in one direction. LEDs are like little
one-way light bulbs.
SCM-165_Manual_061114.qxp_Layout 1 7/7/14 11:30 AM Page 80