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Light dependent tone generator using 555 timer |
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A very simple tone generator circuit based on a 555 timer IC is presented in this schematic diagram . What is so special at this 555 timer IC project ? this circuit use a LDR ( light dependent resistor ) to modify the frequency of the circuit . If the circuit is placed in a constant light the speaker will emit a sound with a constant frequency but we change the intensity of the light the circuit will generate a sound with a frequency that depends of light intensity . If the tone generator circuit is placed in a dark place the circuit don’t emit any sound .
The 555 timer IC is connected in a astable mode and the oscillation time depends of the R1, R2, C1 components value . The speaker connected at the output terminals of the circuit must have a 8 ohms impedance and a power between 0.2-0.5 watts .
The transistor used in this tone generator circuit must be BD136, 2N2905 type or equivalent .
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