Electret Capsule Micro-Phone Pre-Amplifier Using TLV6741 Op-Amp

I am here with one more electret microphone preamplifier. This circuit uses an op-amp in a trans-impedance amplifier configuration to convert the output current from an electret capsule microphone into an output voltage. The common mode voltage of this circuit is Constant and set to mid-supply eliminating any input–stage cross over distortion, Circuit and description of the project from Texas Instruments Application. The circuit is based on TLV6741 Op-Amp from Texas Instruments.

Features

  • Supply 5V DC
  • Input Pressure 100dB SPL(2Pa)
  • Output Voltage 1.228V
  • Frequency Response Deviation @20Hz>-0.5dB,@20Khz>-0.1dB

Download PDF Document


Microphone Parameter

  • Sensitivity @94dB SPL (1Pa) >>-35+/-4dBV
  • Current Consumption (Max)>>0.5mA
  • Impedance>> 2.2KOhms
  • Standard Operating Voltage 2V



Op-Amp TLV6741

The TLV6741 operational amplifier (op-amp) is a general-purpose CMOS op-amp that provides low noise of 3.7 nV/√Hz and a wide bandwidth of 10 MHz. The low noise and wide bandwidth make the TLV6741 device attractive for a variety of precision applications that require a good balance between cost and performance. Additionally, the input bias current of the TLV6741 supports applications with high source impedance. The robust design of the TLV6741 provides ease-of-use to the circuit designer due to its unity-gain stability, integrated RFI/EMI rejection filter, no phase reversal in overdrive conditions and high electrostatic discharge (ESD) protection (1-kV HBM). Additionally, the resistive open-loop output impedance makes it easy to stabilize with much higher capacitive loads. This op-amp is optimized for low-voltage operation as low as 2.25 V (±1.125 V) and up to 5.5 V (±2.75 V), and is specified over the temperature range of –40°C to +125°C. The single-channel TLV6741 is available in a small size SC70-5 package.

20 LED Knight Rider-2 Using arduino mega

Knight Rider-2 simple project using Arduino Mega and 20 LEd.  This example makes use of 20 LEDs connected to the pins 22 – 41 on the board using 40 Ohm resistors and LED driver IC ULN2003. The code example will make the LEDs blink in a sequence, one by one.

Hardware Requirement

  • Arduino Mega
  • ULN2003 X 3 IC
  • 470 Ohms X 20 Resistors
  • Blue LED X 20

Download Arduino Code



Video Of The project


Arduino Code


/* Knight Rider
* Visit www.twovolt.com for Code , Circuit
* Hardware required>>>>Arduino Mega2560 , 20 LED board

*/

int pinArray[] = {22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41};
int count = 0;
int timer = 10;

void setup(){
for (count=0;count<20;count++) {
pinMode(pinArray[count], OUTPUT);
}
}

void loop() {
for (count=0;count<19;count++) {
digitalWrite(pinArray[count], HIGH);
delay(timer);
digitalWrite(pinArray[count + 1], HIGH);
delay(timer);
digitalWrite(pinArray[count], LOW);
delay(timer*2);
}
for (count=19;count>0;count–) {
digitalWrite(pinArray[count], HIGH);
delay(timer);
digitalWrite(pinArray[count – 1], HIGH);
delay(timer);
digitalWrite(pinArray[count], LOW);
delay(timer*2);
}
}


Arduino 20 LED Knight Rider using arduino mega

Arduino Knight Rider LED effects project consist of 20 LEDs and Arduino mega, refer circuit diagram for LED connections to Arduino. This example makes use of 20 LEDs connected to the pins 22 – 41 on the board using 40 Ohm resistors and LED driver IC ULN2003. The code example will make the LEDs blink in a sequence, one by one using only digitalWrite(pinNum, HIGH/LOW) and delay(time).

Hardware Requirement

  • Arduino Mega
  • ULN2003 X 3 IC
  • 470 Ohms X 20 Resistors
  • Blue LED X 20 ( SMD 0805 LED)

Download Arduino Code



Video of the Project



Arduino Code


/*
Arduino 20 LEDs Knight Rider
Hardware 20 LED board, Arduino Mega 2560
Circuit diagram, PCB layout and code of the project is
available from our website www.twovolt.com

*/
//
int ledPin1 = 22;
int ledPin2 = 23;
int ledPin3 = 24;
int ledPin4 = 25;
int ledPin5 = 26;
int ledPin6 = 27;
int ledPin7 = 28;
int ledPin8 = 29;
int ledPin9 = 30;
int ledPin10 = 31;
int ledPin11 = 32;
int ledPin12 = 33;
int ledPin13 = 34;
int ledPin14 = 35;
int ledPin15 = 36;
int ledPin16 = 37;
int ledPin17 = 38;
int ledPin18 = 39;
int ledPin19 = 40;
int ledPin20 = 41;

const int delayTime = 25;
void setup ()

{
pinMode(ledPin1, OUTPUT);
pinMode(ledPin2, OUTPUT);
pinMode(ledPin3, OUTPUT);
pinMode(ledPin4, OUTPUT);
pinMode(ledPin5, OUTPUT);
pinMode(ledPin6, OUTPUT);
pinMode(ledPin7, OUTPUT);
pinMode(ledPin8, OUTPUT);
pinMode(ledPin9, OUTPUT);
pinMode(ledPin10, OUTPUT);
pinMode(ledPin11, OUTPUT);
pinMode(ledPin12, OUTPUT);
pinMode(ledPin13, OUTPUT);
pinMode(ledPin14, OUTPUT);
pinMode(ledPin15, OUTPUT);
pinMode(ledPin16, OUTPUT);
pinMode(ledPin17, OUTPUT);
pinMode(ledPin18, OUTPUT);
pinMode(ledPin19, OUTPUT);
pinMode(ledPin20, OUTPUT);

}
void loop() {

digitalWrite(ledPin1,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin1,LOW); // LED OFF

digitalWrite(ledPin2,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin2,LOW); // LED OFF

digitalWrite(ledPin3,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin3,LOW); // LED OFF

digitalWrite(ledPin4,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin4,LOW); // LED OFF

digitalWrite(ledPin5,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin5,LOW); // LED OFF

digitalWrite(ledPin6,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin6,LOW); // LED OFF

digitalWrite(ledPin7,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin7,LOW); // LED OFF

digitalWrite(ledPin8,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin8,LOW); // LED OFF

digitalWrite(ledPin9,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin9,LOW); // LED OFF

digitalWrite(ledPin10,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin10,LOW); // LED OFF

digitalWrite(ledPin11,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin11,LOW); // LED OFF

digitalWrite(ledPin12,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin12,LOW); // LED OFF

digitalWrite(ledPin13,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin13,LOW); // LED OFF

digitalWrite(ledPin14,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin14,LOW); // LED OFF

digitalWrite(ledPin15,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin15,LOW); // LED OFF

digitalWrite(ledPin16,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin16,LOW); // LED OFF

digitalWrite(ledPin17,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin17,LOW); // LED OFF

digitalWrite(ledPin18,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin18,LOW); // LED OFF

digitalWrite(ledPin19,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin19,LOW); // LED OFF

digitalWrite(ledPin20,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin20,LOW); // LED OFF

//turn

digitalWrite(ledPin20,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin20,LOW); // LED OFF

digitalWrite(ledPin19,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin19,LOW); // LED OFF

digitalWrite(ledPin18,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin18,LOW); // LED OFF

digitalWrite(ledPin17,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin17,LOW); // LED OFF

digitalWrite(ledPin16,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin16,LOW); // LED OFF

digitalWrite(ledPin15,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin15,LOW); // LED OFF

digitalWrite(ledPin14,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin14,LOW); // LED OFF

digitalWrite(ledPin13,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin13,LOW); // LED OFF

digitalWrite(ledPin12,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin12,LOW); // LED OFF

digitalWrite(ledPin11,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin11,LOW); // LED OFF

digitalWrite(ledPin10,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin10,LOW); // LED OFF

digitalWrite(ledPin9,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin9,LOW); // LED OFF

digitalWrite(ledPin8,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin8,LOW); // LED OFF

digitalWrite(ledPin7,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin7,LOW); // LED OFF

digitalWrite(ledPin6,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin6,LOW); // LED OFF

digitalWrite(ledPin5,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin5,LOW); // LED OFF

digitalWrite(ledPin4,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin4,LOW); // LED OFF

digitalWrite(ledPin3,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin3,LOW); // LED OFF

digitalWrite(ledPin2,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin2,LOW); // LED OFF

digitalWrite(ledPin1,HIGH); // LED ON
delay(delayTime);
digitalWrite(ledPin1,LOW); // LED OFF

}

Arduino Based Digital Voltmeter Using 16X2 LCD (Voltage Range 0 to 5V)

The simple digital voltmeter made  using Arduino  Nano and 16X2 LCD, the project is tested on TWOVOLT Multi-Project LCD Shield; Arduino has a couple of 10 Bit ADC pins, we have used A0 pin as an input. The PR2 Trimmer pot used as input voltage, Remove PR2 to measure the external voltage. 16X2 LCD used to display the measured voltage.  Arduino can be power using USB cable or 12V DC at CN1 VDD and GND pin. PR2 5K Ohms or 10K Ohms can be used.

Arduino Pins LCD

  • LCD RS pin to digital pin 12
  • LCD Enable pin to digital pin 11
  • LCD D4 pin to digital pin 5
  • LCD D5 pin to digital pin 4
  • LCD D6 pin to digital pin 3
  • LCD D7 pin to digital pin 2
  • LCD R/W pin to ground

Arduino Pins Vs Devices

  • Switch 1 Arduino Pin A3
  • Switch 2 Arduino Pin D6
  • Switch 3 Arduino Pin D7
  • Current Sensor ACS714 Arduino Pin A5
  • Trimmer Potentiometer Arduino Pin A0
  • LM35 Sensor Arduino Pin A4
  • Power MOSFET Arduino Pin D9
  • Relay Arduino Pin D8

Download Arduino Code


Hardware Required for the Project


Arduino Code for the project


/*
Simple code to mesure the voltage and display on 16X2 LCD, code tested on
Multi project LCD shield from twovolt.com , circuit, pcb layout and code available
at ourwebsite www.twovolt.com and video available at www.youtube.com/thetwovolt
*/
#include “LiquidCrystal.h”

LiquidCrystal lcd(12, 11, 5, 4, 3, 2);

float voltage = 0.0;
float temp=0.0;
int analog_value;

void setup()
{
lcd.begin(16, 2);
lcd.setCursor (0,0);
}
void loop()
{

analog_value = analogRead(A0);
voltage = (analog_value * 5.0) / 1024.0;

if (voltage < 0.1)
{
voltage=0.0;
}
lcd.clear();
lcd.setCursor(0, 0);
lcd.print(“Voltage= “);
lcd.print(voltage);
delay(30);
}


Complete Circuit of Arduino Multi-project LCD Shield