23
Sonic Flasher
Set the slide switch (S1) on, a space war sound plays and the LED
(D1) ashes. Cover the photoresistor (RP) and press the press switch
(S2) to change the sound. See how many sounds are programmed into
the space war sound IC (U3).
Fading Siren
First, place the 470mF capacitor (C5) across points A & B to discharge
it. Then build the circuit as shown on the left. Press the switch (S2),
the integrated circuit should make the sound of an up-down siren that
gets weaker with time. The fading is produced by the charging of the
470mF capacitor (C5). After it is charged, the current stops and the
sound is very weak.
To repeat this effect you must release the press switch (S2), remove
the capacitor (C5), and discharge it by placing it across the snaps on
the bottom bar marked A & B. Then, replace the capacitor (C5) and
press the switch again.
Project 115
Project 114
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