Simple Sound-to-Beep Circuit using IC CD4049

This fun sound-to-beep circuit uses the CD4049 chip and is a simple way to detect sounds.

It can turn a whistle into a beeping sound!

When it hears a whistle it beeps for about three seconds.

You can use it for different things like door alarms remote controls, and other systems that respond to sounds.

The design has a microphone that acts as the sound sensor some operational amplifiers from the CMOS CD4049 Hex inverter series and a transistor that makes a buzzer go off.

You can easily power the whole circuit with a 3V battery.

Circuit Working:

Parts List:

Below are the circuit working for Simple Sound-to-Beep Circuit using IC CD4049

The main component of this circuit is the CMOS IC CD4049.

The electret microphone captures sound waves and converts them into electrical signals.

Resistors R1 and R2 along with capacitor C1 prepare these signals before they enter the Schmitt trigger gate U1a.

Resistor R3 provides essential feedback to keep the signal steady.

Components U1a and U1b amplify the detected sound signal, transforming it into a square wave for future use.

Capacitors C2 and C3 both 10nF along with resistor R6 create a filtering system that minimizes unwanted noise and enhances the stability of the output.

Before the signal reaches the diode D1 it undergoes further conditioning through resistors R7 and R8.

The processed signal from U1c passes through another diode D2 and a transistor Q1 2N2222 which regulates the buzzer

A storage capacitor C6 is crucial for prolonging the beep sound.

Resistors R9 and R10 help control both the sensitivity and the length of the beep.

This circuit operates on a small 3V battery

Capacitors C4 and C5 are utilized to filter out noise from the power supply.

Formulas with Calculations:

Below are the formulas with calculations for Simple Sound-to-Beep Circuit using IC CD4049

Frequency Response of the Microphone Stage:

fc = 1 / (2 * pi * R1 * C1)

where,

• fc is the cutoff frequency in hertz
• π (pi) is mathematical constant (~3.1416)
• R1 is resistance in ohms Ω
• C1 is the capacitance in farads F

here in circuit diagram R1 = 22k and C1 = 47nF

fc = 1 / (2 * 3.1416 * 22000 * 47 * 10^-9)

fc = 154 Hz

This shows the lower frequency response of the microphone circuit.

RC time constant for beep duration:

tau = R9 * C6

where,

• τ (tau) is the time constant in seconds
• R9 is the resistance in ohms Ω
• C6 is the capacitance in farads F

here in circuit diagram R9 = 2.2M and C6 = 1µF

tau = 2.2 * 10^6 * 1 * 10^-6

tau = 2.2 seconds

This shows how long the buzzer remains active after the whistle is detected.

How to Build:

To build a Simple Sound-to-Beep Circuit using IC CD4049 follow the below mentioned steps for connections and assembling:

• Gather all the components as mentioned in the above circuit diagram
• Connect pin 2 of U1a to pin 3 of U1a of IC1 CD4049 through resistor R3
• Connect a resistor R4 from pin 2 of U1a to the junction of resistor R5 and capacitor C2 and C3
• Connect resistor R2 and capacitor C1 in series from pin 3 of U1a to the junction of resistor R1 and electret mic
• Connect pin 4 of U1b to pin 5 of U1b of IC1 CD4049 through resistor R6
• Connect capacitor C2 and capacitor C3 in parallel though pin 4 and pin 5
• Connect resistor R7 between pin 4 of U1b and pin 7 of U1c of IC1 CD4049
• Connect resistor R8 between resistor R7 and pin 7 of U1c and GND
• Connect cathode of diode D1 between pin 6 of U1c of IC1 CD4049 and anode of diode D1 to negative of capacitor C4 and positive of capacitor C4 connect to positive of 3V battery
• Connect pin 8 of U1c of IC1 CD4049 to GND of the circuit
• Connect resistor R9 between pin 14 of U1d of IC1 CD4049 and negative of capacitor C4
• Connect pin 15 of U1d of IC1 CD4049 to cathode of diode D2 and anode of diode D2 connect to one end of capacitor C5
• Connect resistor R10 one terminal to pin 11 of U1e of IC1 CD4049 and other terminal of R10 connect between pin 12 of U1e and pin 9 of U1f of IC1 CD4049
• Connect pin 10 U1f of IC1 CD4049 to base of transistor Q1 through one end of capacitor C5
• Connect the collector of transistor Q1 to positive of 3V battery and emitter of transistor Q1 connect to one end of buzzer and other end of buzzer connect to GND of the circuit
• Connect capacitor C6 positive end to positive of battery and negative of C6 capacitor connect to GND

Conclusion:

This Simple Sound-to-Beep Circuit using IC CD4049 can pick up whistle sounds and turn them into a beeping noise.

By using a Schmitt trigger for processing the signals it works without any background noise.

It is an affordable and effective option for systems that rely on sound for alerts or control.

References:

Datasheet IC CD4049