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Project #347
OBJECTIVE: Making telegraph sounds.
Press the switch (S2) down. The circuit oscillates and the AC voltage
generated from the transformer (T1) drives the speaker (SP). To
make a telegraph sound, depress the switch for long and short
Telegraph
OBJECTIVE: Show variations of project 347.
Use the circuit in project 347. Connect the
whistle chip (WC) across points B & E.
Mosquito
Sound (II)
Project #349
OBJECTIVE: Show variations of project 347.
Mosquito
Sound (III)
Project #350
OBJECTIVE: To use the photo resistor to
adjust the oscillator sound.
Touch-Control
Mosquito Sound
Project #351
OBJECTIVE: Use the whistle chip to make a mosquito sound.
Use the circuit in project 347. Remove the speaker (SP). Connect the
whistle chip (WC) across points C & D to make a mosquito sound.
Mosquito Sound
Project #348
Use the circuit in project 347. Connect the
whistle chip (WC) across points E & D.
Use the circuit in project 347. Replace the
100kΩ resistor (R5) with the photo resistor
(RP). Wave your hand over the resistor and
the sound changes.
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