Elenco Projects 306-511 - Manual (Page 38)

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Project #404
OBJECTIVE: Build an oscillator circuit.
Turn on the slide switch (S1) and the LED (D1) lights as the speaker
(SP) emits a tone. The circuit oscillates and generates an AC voltage
across the speaker through the transformer (T1).
Oscillator Sound
OBJECTIVE: Show variations of project
#404.
Use the circuit in project #404. Place the
whistle chip (WC) in parallel with the capacitor
(C2) by placing it on the left side of the
transformer (T1). Turn on the slide switch (S1)
and you now hear a lower tone.
Oscillator
Sound (III)
Project #406
OBJECTIVE: Show variations of project
#404.
Oscillator
Sound (IV)
Project #407
OBJECTIVE: Show variations of project
#404.
Oscillator
Sound (V)
Project #408
OBJECTIVE: Show variations of project #404.
Use the circuit in project #404. In this circuit, you will change the tone
by adding more capacitance. Place the whistle chip (WC) on top of
capacitor (C1). Turn on the slide switch (S1) and you now hear a lower
tone. Adding the more capacitance lowers the oscillating frequency.
Oscillator Sound (II)
Project #405
Use the circuit in project #404. Using a 1-
snap, place the 10
μ F capacitor (C3) on top of
the 100k Ω resistor (R5), with the “+” side on
point A1. Turn on the slide switch (S1) and
you should hear a much lower sound then the
previous projects.
Use the circuit in project #404. Replace the
100k
Ω resistor (R5) with the photoresistor
(RP). Wave your hand over the photoresistor.
Now, as the resistance changes, so does the
oscillator frequency.