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

4 Channel IR Transmitter and Receiver Module Using ht12A & HT12d

4 Channel Infrared (IR) Remote is a simple project using the popular HT12A and HT12D encoder/decoder chips from Holtek.  The project can be used in latch mode or momentary mode, mode selection possible using J1 Jumper and transmitter end. All output at the receiver end is TTL.

 

Specifications

  •     Supply – Transmitter: 2.4 ~ 5 VDC, 5 V @ 20 mA & Receiver: 5 ~ 6 VDC, 5 V @ 50 mA
  •     Output – 4 Latched/Momentary TTL compatible outputs
  •      Crystal based oscillator for the reliability of operation
  •      DIP switch selectable 8-bit address code
  •      LED output to indicate reception
  •      ON/OFF slide switch in the transmitter
  •      Power-On LED indicator in the Receiver / Transmitter
  •      High noise immunity
  •      Berg connector for interfacing of the board
  •      Four mounting holes of 3.2 mm each
  •      PCB dimensions – Transmitter: 61 mm x 47 mm & Receiver: 46 mm x 46 mm

Balanced Audio head-phone amplifier ( Balanced audio monitor)

Useful audio device for audio professionals, tiny board is a balanced headphone monitor, based on BA4560 op-amp, project works with 12V DC supply, Female XLR connector helps to feed balanced audio input, male XLR connector for parallel balanced signal output, and 3.5MM Stereo EP socket provided to connect headphone, easy supply input using standard DC socket, onboard potentiometer provided to adjust the gain.

Features

  • Supply 12V DC
  • DC Socket for Supply Input Or CN4 Header Connector
  • 3.5MM EP Socket for Headphone
  • Load: 32 Ohms Headphone
  • XLR Female: Balanced Audio Signal Input
  • XLR Male: Balanced Audio Output
  • D1 Power LED

Components:

  • C1, C2 10uF/25V Bipolar Capacitors,
  • C11 220uF/16V , C10 470uF/16V, C1,C2 40uF/25V  Electrolytic Capacitors
  • All Other Capacitors and Resistors SMD 0805
  • IC BA4560 SMD SO8 www.rhom.com

High Precision Low Cost Adjustable Constant Current Source Output 0 to 2.5A

Current sources are widely used in industrial, power supply, LED drivers and other equipment. The project has been developed using the AD8276 difference amplifier and the AD8603 op-amp. Current source using the low power AD8276 difference amplifier and the AD8603 op amp are affordable, flexible, and is small in size. Performance characteristics such as initial error, temperature drift, and power dissipation make the AD8276 and the AD8603 ideal candidates for such project. The circuit provides current 0 to 2.5Amps, input supply 12 to 15V DC. I have tested this board with 4.7E/10W X3 parallel resistors.

Download PDF Schematic

Download AD8276 Data Sheet

Download AD8603 Data Sheet

Features

  • Input 12 to 15V DC
  • Load Current Up to 2.5Amps
  • Current Adjustable 0 to 2.5Amps
  • On Board Trimmer Pot to Adjust the Current
  • Required Large Size Heatsink for full load 2.5Amps

Solid State DC Switching using Mosfet-Arduino nano dc-ssr shield

The simple DC switching possible with this MOSFET board, the board is made in form of Arduino Nano shield, the board can be used to drive inductive load as well as resistive load, possible application for the shield are LED dimmer, DC Motor speed controller, DC load ON/OFF, solenoid driver, and lamp dimmer. D2 provided for back EMF protection which helps to use an inductive load like DC motor or solenoid. The directly seats on top of Arduino Nano, Screw terminal provided to connect the load and Dc supply. This N-Channel MOSFET has been produced using a proprietary PowerTrench® technology to deliver low RDS(on) and optimized BVDSS capability to offer superior performance benefit in the application. FDD8876 MOSFET can drive a high current load, MBRS340 diode protects from back EMF.

Components Details

  • R1 and R2 SMD 5% 0805
  • FDD8876 SMD Mosfet
  • D1 and D2 SMD Mosfets
  • C1, C2 SMD Ceramic 1210 Capacitor
  • CN1,CN2 Screw Terminals 

Features

  • Supply 12V DC
  • Load 4Amps Max
  • PWM Duty Cycle 0 to 100%
  • Arduino Nano D3-PWM Pin-Connected to Mosfet

About MBRS340 Diode

The Schottky Rectifier employs the Schottky Barrier principle in a large area metal-to-silicon power diode. The Schottky Rectifier’s state-of-the-art geometry features epitaxial construction with oxide passivation and metal overlay contact. It is ideally suited for low voltage, high-frequency rectification, or as freewheeling and polarity protection diodes in surface mount applications where compact size and weight are critical to the system.
Features

  • Small Compact Surface Mountable Package with J-Bend Leads
  • Rectangular Package for Automated Handling
  • Highly Stable Oxide Passivated Junction
  • Excellent Ability to Withstand Reverse Avalanche Energy Transients
  • Guarding for Stress Protection

Reduction Assembly for Camera slider, CNC Router, Automation, 3D Printer Using NEMA23 Stepper Motor and timing Pulley

Reduction Assembly  for Camera slider Using Nema 23 Motor and Timing Pulley

Reduction assembly provides 4 times the torque capacity of NEMA 23 motor by using large size pulley and belt. Its features timing pulley on the main out shaft to drive timing belt for linear motion. The unit has been designed to drive professional camera slider however it can be used in various CNC and motion control applications. The unit consists Sanyo Denki high torque NEMA23 motor, 18 teeth HTD timing pulley at motor side and 72 teeth timing pulley at output shaft which provides 1:4 ratio reduction, output has HTD 5MM 20 teeth pulley for slider belt driver.  This unit can be used with rack pinion, use Pinion at output shaft instead of timing pulley.

Features

Reduction Ratio 1:4
Nema 23 Motor
Timing Belt 3MM HTD 15MM Width

Open Ended Timing Belt at Output 15MM width 5MM HTD

Output Timing Pulley 20 Teeth 15MM HTD M5 Pulley

DC Motor Speed Controller with 2 digit display ( Duty Cycle Display)

The versatile DC motor speed controller project is based on PIC16F1825 microcontroller, its generate PWM pulse and also display the value on 2 digit 7 segment display, duty cycle adjustable 0 to 99 %, Frequency 1Khz, the speed of motor possible with help of two tactile switches.  The board only generate and display the PWM, project required Mosfet on output to drive the motor. Check the circuit diagram for the Mosfet circuit.

Note: Output MOSFET can be used as per current and voltage requirements, it is advisable to use isolated DC solid state relay at the output.

Download Hex Code For This Project

Download Data Sheet Of PIC16F1825

Download PDF Schematic

Features

  • Supply 5V DC
  • Motor supply 12V to 30V DC
  • Frequency 1Khz
  • Duty Cycle 0 to 99%
  • Mosfet is outside of the board

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