Condenser mic audio amplifier gives good quality audio of 0.5 watts at 3 volts. We can use this audio amplifier for walkie-talkies, low-power transmitters, and packet radio receivers. BEL 1895 (Bharat Electronics Limited 1895) audio amplifier IC is a noise-free amplifier IC used to construct audio amplifier circuits. In this circuit, we are using a preamplifier section to boost the weak signal from the condenser mic. The pre-amplified signal is connected to BEL 1895 audio amplifier IC. However, the preset in the first transistor acts as a gain controller, it can vary the gain of the amplifier circuit.
Circuit Diagram
Components Required
- Condenser mic
- Speaker
- BEL 1895 IC
- Resistors (2.2kΩ, 470kΩ x2, 470Ω x2, 47kΩ, 33Ω, 1Ω, 1kΩ x2, 100kΩ, 220kΩ, 100Ωx2)
- Preset 10kΩ
- Capacitors (100µF x2, 0.1µF x3, 47µF, 10µF x3, 150µF, 470µF, 1nF x2, 33pF)
Working of Bel 1895 Audio Apmplifier
- Transistors Q1 and Q2 form the condenser mic preamplifier. Resistor R1 provides the required bias for the condenser mic.
- The 10KΩ present at the emitter of Q1 functions to gain control of the voice signal.
- In order to enlarge the audio power, the low-level audio output from the preamplifier stage couples to the audio power amplifier BEL1895 IC via coupling capacitor C1.
- Moreover, BEL1895 exhibits low distortion and noise and operates over 3V-9V supply voltage, which makes it ideal for battery operation.
- BEL1895 is a monolithic audio power amplifier IC, intends particularly for sensitive AM and FM radio applications.
- Coupling capacitor C1 determines the low-frequency response of the amplifier. Capacitor C2 acts as the ripple rejection filter.
- At last, Capacitor C3 connects the output to the loudspeaker. R1-C4 arrangement acts as the damping circuit for output oscillations. Capacitor C5 provides the bootstrapping function.
PCB Layout of Audio Amplifier
Components Pin Out
Conclusion
Here we see an important project for every electronic enthusiastic. To conclude, a mic audio amplifier circuit can easily be implemented using Bel 1895 IC and is useful to be used in various types of sound speakers to amplify the output sound. Moreover, both the circuit diagram and PCB layout is discussed above
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