The first one is a single transistor simple microphone circuit, very simple to hook up using an electret microphone or MIC and an audio amplifier.
Typically the 10K resistor within the microphone's positive port offers this specific vital voltage for the procedure. The capacitor of 100nF on that particular network prevents the DC component of the transmission permitting the AC from the audio to get into the transistor amplifier through its base. The 10K resistor attached to the transistor through its collector enables the triggering of that component, while the 100K causes the feedback of the signal. The output capacitor obstructs the DC component making just the audio signal to go to the following stage.
The circuit could be driven using any voltage between 3 and 9 volts not really being stabilized. However it is crucial that this supply is nicely filtered and decoupled. With regard to this, it is easy to put a 100μF capacitor together with a 100nF capacitor in parallel with the power line within the circuit.
This second design is a very handy little dynamic microphone amplifier circuit for amplifying weaker audio signal coming from a capacitive condenser microphone.
You may use this kind of dynami MIC amplifier circuit for audio sensing purposes and several programmed robotic receptors. This particular condenser microphone DIY audio audio amplifier is extremely tiny and straightforward to utilize since it makes use of only a couple of general purpose transistors plus some discrete components. You are able to build this circuit using a minimal price. This circuit is suitable for inexpensive sound amplification requirements in electronics for example pre-amplifier for FM audio receivers.
Audio amplifier circuit
Resistors 1K, and 100K 1/4 watt
Transistors any small signal type such BC547 or 2N3053
Speaker (8Ω, ½ Watt)
Working of amplifier
The two transistor MIC amplifier circuit is isolated into three sections: Condenser mic, audio amplifier and loudspeaker.
Condenser microphone is really a type of capacitive sound sensor (audio transducer) that will switch the sound (audio) signal directly into electrical impulses.
These electrical impulses tend to be far too weak it is therefore amplified through the amplifier unit. The increased output is acquired over the loudspeaker.
The output of condenser mic is actually combined by using a coupling capacitor of 10µF, the objective of this capacitor would be to eliminate DC material in the audio transmission.
A 1kΩ resistor is employed to offer the necessary biasing to the condenser microphone.
Transistor Q1 is set up as collector to base biasing function. This really is achieved through 100kΩ resistance. This resistor offers negative feedback for the transistor Q1.
The output of Q1 reaches at the collector (throughout 1kΩ resistor), that is the input to the transistor Q2 through a 0.1µF capacitor. The capacitor eliminates DC voltages because of the biasing of Q1.
Transistor Q2 is designed like fixed bias by using a 100kΩ resistor. Additionally, it offers additional amplification.
The amplified output through Q2 can be obtained over the 1kΩ resistor.
The 10µF electrolytic capacitor likewise employed to block the DC voltages of this particular biasing of transistor Q2.
Work with a 8Ω, ½ watt speaker to listen to the amplified signal.