Elenco Green Projects - Manual (Page 62)

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Project #97 Light & Sound Signal
for Radio
Project #96 Light Signal for Radio
Install the battery eliminator connector into
the battery compartment in the radio and
plug in the earphones. Set up the circuit as
shown. Set the slide switch (S5) to position
C, turn on the volume knob on the radio,
and press the scan button to see if you can
find a radio station (radio features may
vary). The red LED (D1) lights, indicating
that electricity is flowing to the radio, but
there may not be enough to operate it.
Disconnect the black wire from the battery
eliminator and the red LED gets dim or
turns off. The two LED’s are in series and
there may not be enough voltage to light
both.
Reconnect the black wire and push the
press switch (S2), to bypass the red LED.
All the voltage is now across the yellow
LED and the radio, so the red LED is off
and the yellow LED lights as the radio
plays.
Modify the preceding circuit by placing the horn
(W1) across the points marked, A and B (“+” side
to B) and the 470
μF capacitor (C5) across points
C and D (“+” side to D).
Set the slide switch to position C and turn the
radio on. The horn will sound but the red LED will
not light. Press S2 and the horn stops, the yellow
LED turns on, and the radio plays.
C
B
D
A
See projects 1 & 3 if you need to recharge the battery (B4).