Tuesday, January 19

digital-sound-level-meter










This circuit is a digital sound level meter with a LCD screen, capable of displaying 80 characters (4 rows with 20 characters on each). You can build this LCD display. It also provides more debugging information, such as the minimum and maximum analog-to-digital samples that were measured during each period.

Analog Amplifier Circuit
This is a simple model for the NPN bipolar junction transistor (BJT), biasing, how to calculate gain, and adding more gain at higher frequenies with a technique called "bypassing".

In the sound meter schematic, the 100K potentiometer is adjusted until the transistor's collector current is approximately 100 microamps (10-4 amps). This is measured with a voltmeter across RE until the voltage is approximately 0.33 volts. Please watch the video for a full explanation of the transistor model and how we build up to this circuit.

Source Code
Microcontroller are based around an Atmel ATmega168 series microcontroller (MCU). These are powerful, industrial grade MCUs, and we help you build a full system around them. This microcontroller has a CPU, permanent storage (flash memory), temporary storage (static RAM), and inputs and outputs.

You can download the source code here. Start with the standard NerdKits microcontroller project and Makefile (included with the kit) and plug in this source code

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