## 20 LED Bar-Graph Voltmeter Using Arduino Mega

Simple 20 LED Segment Bar-Graph Voltmeter , each LED display 0.25V, this circuit can measure 5V directly or it can measure higher voltage  using resistor divider.

Turns on a series of blue LEDs based on the value of an analog voltage input.  This is a simple way to make a bar graph display. Though this graph uses 20 LEDs, you can use any number by changing the LED count and the pins in the array. This method can be used to control any series of digital outputs that depends on an analog input.

Potentiometer is connected to Analog pin A0 of Arduino Mega, VCC and GND

LED Connected to digital pin of Arduino Mega  D22, D23, D24, D25, D26, D27, D28, D29, D30, D31, D32, D33, D34, D35, D36, D37, D38, D39, D40, D41

Note : Circuit can measure 5V DC  voltage,  High voltage can be measure using resistor divider.

The bar graph – a series of LEDs in a line, such as you see on an audio display – is a common hardware display for analog sensors. It’s made up of a series of LEDs in a row, an analog input like a Potentiometer, and a little code in between. You can buy multi-LED bar graph displays fairly cheaply, like this one. This tutorial demonstrates how to control a series of LEDs in a row, but can be applied to any series of digital outputs.

Watch Video Of This Project

Arduino Code

/*
* 20 LED Bargraph Meter , Code writen for arduino mega, project consist
20 blue LED, ULN2003 X 3 as LED driver, code, schematic, PCB layout
available at our website www.twovolt.com

*/

// these constants won’t change:
const int analogPin = A0; // the pin that the potentiometer is attached to
const int ledCount = 20; // the number of LEDs in the bar graph

int ledPins[] = {
22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41
}; // an array of pin numbers to which LEDs are attached

void setup() {
// loop over the pin array and set them all to output:
for (int thisLed = 0; thisLed < ledCount; thisLed++) {
pinMode(ledPins[thisLed], OUTPUT);
}
}

void loop() {
// map the result to a range from 0 to the number of LEDs:
int ledLevel = map(sensorReading, 0, 1023, 0, ledCount);

// loop over the LED array:
for (int thisLed = 0; thisLed < ledCount; thisLed++) {
// if the array element’s index is less than ledLevel,
// turn the pin for this element on:
if (thisLed < ledLevel) {
digitalWrite(ledPins[thisLed], HIGH);
}
// turn off all pins higher than the ledLevel:
else {
digitalWrite(ledPins[thisLed], LOW);
}
}
}

## INVERTING AMPLIFIER SCHEMATIC PCB USING TLV170

INVERTING AMPLIFIER SCHEMATIC PCB CALCULATION USING TLV170

Design Description

This design inverts the input signal, Vi, and applies a signal gain of –2V/V. The input signal typically comes from a low-impedance source because the input impedance of this circuit is determined by the input resistor, R3. The common-mode voltage of an inverting amplifier is equal to the voltage connected to the non-inverting node, which is ground in this design. D1 indicates the power, all connection can be done using CN1 header connector, Capacitors, Resistors, LEDs are SMD components size 0805. Op-Amp TLV170 from Texas Instruments.

D1=Power LED, CN1= 6 Pin male header connector

DESIGN GOALS
ViMIN=-7V, ViNMAX=7V, VoMIN=–14V, VoMAX=14V, F=3KHZ, V+=15V, V-=-15V

Design Notes

1. Use the op amp in a linear operating region. Linear output swing is usually specified under the AOL test conditions. The common-mode voltage in this circuit does not vary with input voltage.
1. The input impedance is determined by the input resistor. Make sure this value is large when compared to the source’s output impedance.
1. Using high value resistors can degrade the phase margin of the circuit and introduce additional noise in the circuit.
1. Avoid placing capacitive loads directly on the output of the amplifier to minimize stability issues.
2. Small-signal bandwidth is determined by the noise gain (or non-inverting gain) and op amp gainbandwidth product (GBP). Additional filtering can be accomplished by adding a capacitor in parallel to R1. Adding a capacitor in parallel with R1 will also improve stability of the circuit if high value resistors are used.
1. Large signal performance may be limited by slew rate. Therefore, check the maximum output swing versus frequency plot in the data sheet to minimize slew-induced distortion.

Application Courtesy of Texas Instruments

## 10 LED Bar-Graph Display- 10 Segment Bar-Graph Voltmeter Arduino Nano

Turns on a series of 10 Segments of LEDs based on the value of an analog sensor. This is a simple way to make a bar graph display. This method can be used to control any series of digital outputs that depends on an analog input. Trimmer Potentiometer and Analog joystick used to test the code.

• 10 3MM LEDs
• 470 E Series Resistor to limit the current to LED
• 5K Ohms Trimmer Potentiometer/10K Joystick used to test the code

Video Available Here

Arduino Code 10 LED Bar-Graph Display / Bar-Graph 5 Voltmeter

/*
LED bar graph

Turns on a series of LEDs based on the value of an analog sensor.
This is a simple way to make a bar graph display. Though this graph uses 10
LEDs, you can use any number by changing the LED count and the pins in the
array.

This method can be used to control any series of digital outputs that depends

The circuit:
– LEDs from pins D2 through D11 to ground
-Trimmer Potentiometer 5K on A0

*/

// these constants won’t change:
const int analogPin = A0; // the pin that the potentiometer is attached to
const int ledCount = 10; // the number of LEDs in the bar graph

int ledPins[] = {
2, 3, 4, 5, 6, 7, 8, 9, 10, 11
}; // an array of pin numbers to which LEDs are attached

void setup() {
// loop over the pin array and set them all to output:
for (int thisLed = 0; thisLed < ledCount; thisLed++) {
pinMode(ledPins[thisLed], OUTPUT);
}
}

void loop() {
// map the result to a range from 0 to the number of LEDs:
int ledLevel = map(sensorReading, 0, 1023, 0, ledCount);

// loop over the LED array:
for (int thisLed = 0; thisLed < ledCount; thisLed++) {
// if the array element’s index is less than ledLevel,
// turn the pin for this element on:
if (thisLed < ledLevel) {
digitalWrite(ledPins[thisLed], HIGH);
}
// turn off all pins higher than the ledLevel:
else {
digitalWrite(ledPins[thisLed], LOW);
}
}
}

## 12V-SLA Lead Acid Battery Charger Using BQ24450

The project has been developed to charge the SLA (Lead Acid Battery) . The project helps to charge 12V Lead acid battery up to 12Ah, specific current output possible altering the current sense Resistor.  The BQ24450 chip contains all the necessary circuitry to optimally control the charging of valve-regulated lead-acid batteries. The IC controls the charging current as well as the charging voltage to safely and efficiently charge the battery, maximizing battery capacity and life. Depending on the application, the IC can be configured as a simple constant-voltage float charge controller or a dual-voltage float-cum-boost charge controller.

The built-in precision voltage reference is especially temperature-compensated to track the characteristics of lead-acid cells, and maintains optimum charging voltage over an extended temperature range without using any external components. The ICs low current consumption allows for accurate temperature monitoring by minimizing self-heating effects.

The IC can support a wide range of battery capacities and charging currents, limited only by the selection of the external pass transistor. The versatile driver for the external pass transistor supports both NPN and PNP types and provides at least 25mA of base drive.

In addition to the voltage- and current-regulating amplifiers, the IC features comparators that monitor the charging voltage and current. These comparators feed into an internal state machine that sequences the charge cycle. Some of these comparator outputs are made available as status signals at external pins of the IC. These status and control pins can be connected to a processor, or they can be connected up in flexible ways for standalone applications.

• Input Supply 16V-20V DC
• Charging Voltage 12V SLA(Lead Acid Battery),AGM
• Lead Acid Battery 5-12Ah  ( 500mA)

The circuit is to use dual Transistor for current up to 1A-15Amps, use proper transistor as per current requirement.

NOTE : This board has been designed for dual transistor, for load current up to 1Amp use single PNP transistor as such TIP32 TO220, Omit Q2 and use Q1, Transistor pins configuration as shown in bellow picture. Omit R5 and R6 is 0 Ohms.

6V Lead Acid SLA Battery Charger Circuit Using BQ24450

The bq24450 board assists users in evaluating the BQ24450 linear battery charger IC. The User’s guide the bq24450 bill of materials, schematic. The bq24450 contains all the necessary circuitry to optimally control the charging of lead-acid batteries. The IC controls the charging current as well as the charging voltage to safely and efficiently charge the battery, maximizing battery capacity and life. Depending on the application, the IC can be configured as a simple constant-voltage float charge controller or a dual-voltage float-cum-boost charge controller. This 6V Lead Acid Charger circuit from www.ti.com EVM manual

• Input Supply 9-13V DC
• Charging Voltage 6V SLA(Lead Acid Battery),AGM
• Lead Acid Battery 5-12Ah  ( 500mA)

Circuit Courtesy www.ti.com

## Universal Instrument Amplifier Development Board Using SMD Components

Universal Instrument Amplifier Development Board ( Prototype Board)  Using SMD Components

## Universal Dual Op-Amp Development PCB & Schematic using THT Components

The Universal Op-Amp Development board is a general purpose blank circuit boards that simplify prototyping circuits for a variety of Op-Amp circuits. The evaluation module board design allows many different circuits to be constructed easily and quickly.

Universal Dual Operational Amplifier (Op-Amp) board is designed to aid in the evaluation and testing of the low voltage/low power and some precision operational amplifiers. This board will accommodate Dual op amp that are assembled in a 8 Pin Dip package. This board is designed to use single or dual amplifiers. Many different circuits can be made such as inverting, non-inverting, differential-In amplifiers and low-pass, band-pass, band reject, or notch second order filters. The amplifier can be powered with single or dual supplies. These circuits can be configured without any modifications to the board, all that is necessary is to select the correct resistors and capacitors. The other optional components can be left open or shorted depending on the configuration desired.

Power is applied to the Header connector pins labeled VCC,-VEE, GND, If a single supply is used, then -VEE should be connected to GND.

This board mainly support lots of Texas instruments Op-Amps, On Semi, Analog Devices

List Of Op-Amps Can be use

• OPA2350
• OPA2340
• LM358
• LF422

Inverting Operational Amplifier Circuit ( Universal Op-Amplifier Development Board)

This is most widely used operational amplifier circuit.  It is an amplifier whose closed-loop gain is set by R27 & R18. It can amplify AC or DC Signal.

Non Inverting Operation Amplifier ( Universal Op-Amplifier Development Board)

This simple circuit is a non-inverting Operation Amplifier can be made using universal Op-Amplifier Development Board. Output voltage has same phase as the input voltage ( For DC Input)

## Universal Dual Op-Amp Development Board & Schematic using SMD Components

Universal Dual Op-Amp Development Board using SMD Components

## LM324 Op-Amp Inverting Amplifier Application and Gain Calculation

The LM324 and LM2902 operational amplifiers are useful in a wide range of signal conditioning applications. Inputs can be powered before VCC for flexibility in multiple supply circuits.

A typical application for an operational amplifier in an inverting amplifier. This amplifier takes a positive voltage on the input, and makes it a negative voltage of the same magnitude. In the same manner, it also makes negative voltages positive. This application is from www.ti.com

## Isolated 0-5V Converter PCB & Schematic

Isolated 0-5V Converter PCB

## Function Generator Using XR2206 Circuit & PCB Layout

Function Generator Using XR2206 Circuit & PCB Layout

1 2 3 4