Elenco Projects 102-305 - Manual (Page 32)

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Project #185
OBJECTIVE: To build a circuit that
makes a loud whine.
Whiner
Project #187
Hummer
OBJECTIVE: To show how adding
capacitance reduces frequency.
Now place the 0.1 μ F capacitor (C2) above
the whistle chip (WC) and vary the adjustable
resistor (RV) again. The frequency (or pitch)
of the whine has been reduced by the greater
added capacitance and it sounds more like a
hum now.
Project #188
Adjustable
Metronome
OBJECTIVE: To build an adjustable
electronic metronome.
Now place the 10 μ F capacitor (C3, “+” side on
right) above the whistle chip (WC) and vary
the adjustable resistor (RV) again. There is
no hum now but instead there is a click and a
flash of light repeating about once a second,
like the “beat” of a sound. It is like a
metronome, which is used to keep time for the
rhythm of a song.
Project #189
Quiet Flasher
OBJECTIVE: To make a blinking
flashlight.
Leave the 10 μ F capacitor (C3) connected but
replace the speaker (SP) with the 2.5V lamp
(L1).
Project #186
Lower Pitch
Whiner
OBJECTIVE: To show how adding
capacitance reduces frequency.
Place the 0.02 μ F capacitor (C1) above the
whistle chip (WC) and vary the adjustable
resistor (RV) again. The frequency (or pitch)
of the whine has been reduced by the added
capacitance.
Build the circuit, turn it on, and move the
setting on the adjustable resistor (RV). It
makes a loud, annoying whine sound.
The green LED (D2) appears to be on,
but it is actually flashing at a very fast
rate.