Elenco Snap Circuits Motion - Manual (Page 74)

Set the switcher (S6) to the middle position. Turn on the slide switch
(S1), nothing happens. Now set S6 to the top position; the red/yellow
bicolor LED (D10) takes a few seconds to turn on. Now set S6 back to
the middle position; the LED will very slowly get dim. The adjustable
resistor (RV2) controls the shut-off time.
You can reverse the orientation of the red/yellow bicolor LED, or replace
it with the color LED (D8, “+” on left).
Project 151 Slow Light
Project 152 Wiggler
Build the circuit as shown, place the spout on the air fountain (AF), place
the ball in the spout, set the lever on the adjustable resistor (RV2) to
the top, and turn on the slide switch (S1). Use the lever on the
adjustable resistor to adjust the brightness of the red/yellow bicolor LED
(D10) and make the ball move or “wiggle” around in the spout.
The ball will only move for a small part of RV2’s adjustment range. If you
replace the red/yellow LED with a 3-snap wire, the ball will move more.
-73-
The 100mF capacitor (C4) controls the red/yellow
LED through the NPN transistor (Q2). Setting S6
to the top position quickly charges up the
capacitor, and setting S6 back to the middle
position allows the capacitor to slowly discharge.
Capacitors can store electric charge and release
it when needed, so they are often used in timing
circuits like this.
This circuit uses the NPN transistor (Q2) and
adjustable resistor (RV2) to control the power to
the air fountain. A small electric current into the
transistor through RV2 and the LED (D10)
controls a larger current into the transistor through
the air fountain. RV2 cannot be used to control the
air fountain directly, because its high resistance
would prevent the air fountain from operating.
Place the
spout on top
of the air
fountain and
the ball in the
air flow.
Spout
SCM-165_Manual_061114.qxp_Layout 1 7/7/14 11:29 AM Page 74