Elenco Upgrade Kit SC300 to SC750 - Manual (Page 30)

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Project #377
OBJECTIVE: To build an alarm circuit.
The circuit uses the space war IC (U3) and works the same way as
project #320. Remove the jumper wire and a space war sound plays.
Space War Alarm by SCR
Project #379
OBJECTIVE: To build an alarm circuit.
Alarm by SCR
Project #378
OBJECTIVE: To build an alarm circuit.
Use the circuit in project #377. Replace the resistor (R3) with the
photoresistor (RP) and remove the jumper wire. Cover the
photoresistor with your hand. Now slowly remove your hand. The
music plays when enough light hits the resistor.
Light Space War Alarm
The circuit uses the alarm IC (U2) and works the same way as project
#377. Remove the jumper wire and an alarm IC sounds.
Project #380
OBJECTIVE: To build an alarm circuit.
Use the circuit in project #379. Replace the 10k Ω resistor (R4) with
the photoresistor (RP) and remove the jumper wire. When enough
light strikes the photoresistor, the Alarm IC (U2) plays. Cover the
photoresistor with your hand. Now slowly remove it, when enough light
hits the resistor, the IC plays.
Light & Alarm IC