A megaphone, also known as a bullhorn or loudhailer, is a device that amplifies sound, typically a person's voice, to be heard over greater distances. It's a cone-shaped acoustic horn that's portable and easy to use. Here designed a mini megaphone circuit using a single Op-Amp LM386 and some discrete components, which makes it a useful, portable, and very cost-effective solution.
Components List
The following components are required to make this diy mini megaphone:
- U1: LM386N Low-voltage audio-power amplifier IC - 1 pcs.
- Q1: Electret mic 9x6mm - 1 pcs.
- R1: 2.2kΩ 1/4W Resistor - 1 pcs.
- R2: 10Ω 1/4W Resistor - 1 pcs.
- R3: 10kΩ Trimmer potentiometer - 1 pcs.
- SW1: Tactile push button switch 6x6x5mm - 1 pcs.
- C1: 220nF Ceramic capacitor - 1 pcs.
- C2: 100nF Ceramic capacitor - 1 pcs.
- C3, C4: 470uF 16V Electrolytic capacitor - 2 pcs.
- SPKR1: 8Ω Horn speaker - 1 pcs.
- J1, J2: 2-Pin Screw terminal connector - 2 pcs.
Mini Megaphone Circuit Diagram
The schematic of diy mini megaphone circuit using lm386 is shown below.
![Mini Megaphone - Circuit Diagram Schematic of Mini Megaphone Circuit using LM386](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiwxBAFGr8gJFB8Mn_xn4P1nHBxHIQ76382rWqi22IXAP2LO0m9wA583rf25Y5ouXt9hwCaZdsV5oQG28bYKjRcz6cff8dZifGP9oHuoScTkR0hlThRjYnNLmhVFUO-4f5yF5huvPjt2IHyKrOHR3JVAVEmC1Wp3fMHrD1hqi4P_16dqBiARlswGLWC0IQw/s1280-rw/schematic-of-mini-megaphone-circuit-using-lm386.png)
The working principle of the mini megaphone circuit is simple. The main component of the circuit is the popular LM386 (U1), which is used to drive low-impedance loads such as an 8Ω speaker, and operates on a single supply voltage ranging from +4 to +12 V. The complete Technical Details can be found in the LM386 datasheet .
When the user presses the push button, the input DC voltage turns on the circuit. The input voice from the electret microphone (Q1) is converted into a signal, which is then fed into a non-inverting operational amplifier (Op-amp) circuit. This Op-amp amplifies the sound through an external horn speaker (SPKR1), allowing it to be heard over greater distances. The output sound volume can be regulated using a trimmer potentiometer (R3).
Mini Megaphone PCB Design
Assemble the circuit on a PCB as it saves time and minimizes assembly errors. An actual-size, single-side PCB with component layout for the mini megaphone circuit is shown below. Carefully assemble the components and double-check for any overlooked errors.
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Mini Megaphone PCB Layout. | A PCB for the mini megaphone circuit. |
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