This is Megaphone circuit diagram is a signal sound expansion from a condenser microphone gives with a small-sized loudspeaker. It composes the importance is part pre mic use transistor just one enlarge sound signal gives the power goes up to change come to a part amplifier with the integrated circuit LM386 utter go out give a loudspeaker.
When feed 9V power supply reach the circuit. The MIC1 and Q1 which be part pre mic, by mic will take sound signal that has come in then deliver Q1 enlarge a signal has power size goes up to go out the way collector pin (C) change C2 coupling signal.
Then deliver with VR1 for fine signal sound level gives with Input of IC1. Which IC1 number LM386 be the integrated circuit amplifies 1-watt size has pin 3 are input and have C3 will eradicate source noise with input signal discharge down the ground.
When amplify finished will export comes to the way output pin 5 by have C5 and R5 eradicate a signal takes to stir go out sound signal will have that to change go to still.
The C6 coupling signal and enhance the sound quality of low frequency improve. Before reach, a loudspeaker makes a noise to come out.
LM380 Simple megaphone circuit
Here is another Simple Megaphone circuit. lightweight portable size, 5-watt sound. It is suitable for your uses at any time. You do not need to speak loudly. It will boost up your voice to higher.
In the circuit using LM380 is a power amplifier and output to a mini speaker. It uses a 9V battery as a power supply. Because we want small size and cheap. You can do it!
How the circuit works
When we press the switch-S1. The circuit is working. But no sound came out.
Then, when any sounds to MIC1, a condenser microphone. It converts these sound signals to electrical signals.
Next, it comes to the potentiometer-VR1(Volume) to adjust this signal before to C1.
C1 is a coupling capacitor. It allows or filter the only audio signal through it, and block DC from the input.
The audio signal comes to IC1-LM380—Mini Power Amplifier IC—. When we use it the life is easy. It requests a few components only.
- Wide Supply Voltage Range: 8V-22V
- Voltage Gain Fixedoutput0
- Max watts ouput: 5W
- Low Quiescent Power Drain: 0.13W (At voltage supply is 18V)
- High Peak Current Capability: 1.3A
The higher audio signal rises out of Pin 8 to the output coupling-C5. And finally, to drive the speakers.
In addition, the R1 and R4 protect all noise signals.
IC1: LM380 mini power amplifier
C1: 3.3uF 25V
C3: 4.7uF 25V
C5,C6: 220uF 25V
C2: 47pF 50V
C4: 0.047uF 50V
R1: 10 ohms 0.25W resistor tolerance: 5%
VR1: 50K Potentiometer
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