Organize and Share your Electronics the way you want. Sign-Up for a free account now. It takes only 30 seconds!

Speech Amplifier Box

Speech Amplifier Box

This circuit is intended to be placed in the same box containing the loudspeaker, forming a compact microphone amplifier primarily intended for speech reinforcement. A device of this kind is particularly suited to teachers, lecturers, tourists’ guides, hostesses and anyone speaking in crowded, noisy environment.
The circuit’s heart is formed by the TDA7052 Audio power amplifier IC, delivering a maximum output of 1.2W @ 6V supply. An external microphone must be plugged into J1, its signal being amplified by Q1 and fed to IC1. R1 acts as a volume control and C3 tailors the upper audio frequency band, mainly to reduce the microphone possibility of picking-up the loudspeaker output, causing a very undesirable and loud “howl”, i.e. the well known Larsen effect.
Therefore, C3 value can be varied in the 4n7 – 22nF range to ensure the best compromise from speech tone quality and minimum Larsen effect occurrence. For the same reason, the use of an uni-directional (cardioid) dynamic or electret microphone is warmly recommended.
Most of these microphone types are usually fitted out with a slider switch: this is an useful feature that can be used to momentarily mute the microphone. Some microphone types use a separate jack for connection to the muting circuit, some others use a stereo jack or different plug types. In any case, the connection of this switch to the circuit is shown as SW1 in the diagram.

Visit Here for more.

 

More Articles to Read

App note: Testing inductors at application frequencies
App note: Testing inductors at application frequencies
App note: Working voltage ratings applied to inductors
App note: Working voltage ratings applied to inductors
1968 Princeton Reverb Repairs
1968 Princeton Reverb Repairs
Skill Sunday: Power Over Ethernet for Arduino
Skill Sunday: Power Over Ethernet for Arduino
More on Color TFT Displays ~ The Big Ones — 240 X 320
More on Color TFT Displays ~ The Big Ones — 240 X 320
Vertical Pole Climbing Robot
Vertical Pole Climbing Robot
ESP8266 Weather Station Projects
ESP8266 Weather Station Projects
Single tube Lethal Nixie clock
Single tube Lethal Nixie clock
How to make a simple 1 watt audio amplifier (LM386 based)
How to make a simple 1 watt audio amplifier (LM386 based)
Flashing Binaries to DRA7xx Factory Boards Using Device Firmware Upgrade
Flashing Binaries to DRA7xx Factory Boards Using Device Firmware Upgrade

Top




Shares