Arduino Nano Blink and Buzz Project Using 11 LEDs & Buzzer

Another project using Arduino Nano 11 LEDs and buzzer shield, LEDs connected  to D2-D12 of Arduino Nano and buzzer connected to D13 of Arduino Nano,  Simple example code flashing at speed of 100mili seconds on/off.

Watch Video On You Tube









Arduino Code

Blink & Buzz Code

Turns on LEDS & Buzzer for 100 Mili seconds,
then off 100 Mili seconds, repeatedly.
This example code is based on example code
that is in the public domain.
void setup() {
// initialize the digital pin as an output.
// Pin 2-11 has LEDs & Pin 13 has buzzer connected on Arduino:
pinMode(2, OUTPUT);
pinMode(3, OUTPUT);
pinMode(4, OUTPUT);
pinMode(5, OUTPUT);
pinMode(6, OUTPUT);
pinMode(7, OUTPUT);
pinMode(8, OUTPUT);
pinMode(9, OUTPUT);
pinMode(10, OUTPUT);
pinMode(11, OUTPUT);
pinMode(12, OUTPUT);
pinMode(13, OUTPUT);
void loop() {
digitalWrite(2, HIGH); // set the LED on
digitalWrite(3, HIGH); // set the LED on
digitalWrite(4, HIGH); // set the LED on
digitalWrite(5, HIGH); // set the LED on
digitalWrite(6, HIGH); // set the LED on
digitalWrite(7, HIGH); // set the LED on
digitalWrite(8, HIGH); // set the LED on
digitalWrite(9, HIGH); // set the LED on
digitalWrite(10, HIGH); // set the LED on
digitalWrite(11, HIGH); // set the LED on
digitalWrite(12, HIGH); // set the LED on
digitalWrite(13, HIGH); // set the Buzzer on
delay(100); // wait for a second
digitalWrite(2, LOW); // set the LED off
digitalWrite(3, LOW); // set the LED off
digitalWrite(4, LOW); // set the LED off
digitalWrite(5, LOW); // set the LED off
digitalWrite(6, LOW); // set the LED off
digitalWrite(7, LOW); // set the LED off
digitalWrite(8, LOW); // set the LED off
digitalWrite(9, LOW); // set the LED off
digitalWrite(10, LOW); // set the LED off
digitalWrite(11, LOW); // set the LED off
digitalWrite(12, LOW); // set the LED off
digitalWrite(13, LOW); // set the Buzzer off
delay(100); // wait for a second





480 Seconds Voice Record/Playback Circuit with PCB Layout Using ISD17240 IC

Project has been designed for record & playback multi voice massages applications using nuvton ISD17240 IC.  Messages are stored in flash memories made in unique Multilevel Storage Technology (MLS).  Circuit  provides high quality audio recording and simple operations.  Circuit operates in dual mode standalone or micro-controller SPI mode.  Onboard tactile switches for standalone mode and 10 (2×5) pin box header connector for SPI mode.  160-480 Seconds voice massage recording capacity.

ISD1700 product is recommend for new designs in the 20 to 480 seconds storage duration (See Table1 below for cross reference parts) because of its simpler interface automatic power-down and new features such automatic message management, PWM speaker driver, volume control, vAlert, Erase operation, and configurable current (AUD) or voltage (AuxOut) output to drive external power amplifier.

NOTE : The PCB board can accommodate following ICs ISD1730, ISD1740, ISD1760, ISD17120 and ISD17240.






  • Supply 2.4 to 5 VDC (5 VDC @ 100 mA)
  • 26 to 80 Seconds selectable voice recording capacity
  • Selectable sampling rates 4KhZ To 12Khz
  • Directly drive 8 Ohms speaker or typical buzzer
  • Analog audio out to driver external audio amplifier
  • Digital volume control via onboard tactile switch
  • Dual mode operation stand alone or micro-controller
  • SPI Interface (4 wire serial interface)
  • 10 (2×5) Pin box header for SPI interface
  • Full control on memory and analog path configuration audio input, output and mix in SPI mode
  • Automatic power-down after each operations cycle (standalone mode)
  • Onboard tactile switch for Record, Play, Erase, FWD, Volume control, Reset and Feed-Through
  • Onboard power indication, record play indication
  • Voice message fed in via microphone or analog signal in
  • ISD1740 provides a PWM class D speaker driver and speaker output simultaneously
  • 100 Years message retention
  • 100,000 Record cycles
  • Four mounting holes of 3.2 mm each
  • PCB dimensions 80 mm x 76 mm




SW1 (Recording)

Push switch for triggering REC function Recording initialized by HL edge of this signal, continues when it stays at L and stops when LH edge occurs or memory is full.  In standalone mode, massages are recorded sequentially until end of memory.  The location where recording of individual message starts is determine by the internal record pointer. Addressable record and playback operations are accessible only in SPI mode.

SW2 (Reset)

Push switch for triggering reset function – device enter into the initial state and initializes all pointers to the default state without erasing recording massages.

SW3 (Play)

Push switch for triggering the Play function – playback of current massage in memory.  Beginning of current massage determined by the internal playback pointer.  Short Low pulse start the playback of this massage and next pulse low stop this operation.

SW4 (Erase)

Push switch for triggering the erase function – Erasing the first or last message in memory or global erasing the all message (whole memory).  Short Low pulse erases the current message.  Holding this input for more then 3Seconds initiates the global erase operations.


Push switch for triggering the FWD function – Forward operations, advance to the next massage.  Short pulse causes. In standby mode advance from current message to the next message (one message forward) and setting the pointer the playback pointer on it.  During the playback-halting this process, advancing to the next massage and restarting the playback from beginning.

SW6 (Volume)

Push switch for triggering Volume – Control of audio volume on speaker output, Analog audio output and Aux/Audio output.  There are 8 steps of volume control.  Default value after power on is maximum.  Repeated low pulses decrease the level by 1 step until the minimum value reached and then increase the volume by one step until maximum value reached and so on.

SW7 (FT)

Push switch for triggering the FT function – In stand alone mode, it configures the analog path as feed-through path from ANA IN audio input to Speakers output and Aux Audio output.






PCB Top Silk Screen


PCB Top layer


PCB Bottom Layer


Bill Of Material


The Nuvoton ISD1700 ChipCorder Series is a high quality, fully integrated, single-chip multi-message voice record and playback device ideally suited to a variety of electronic systems. The message duration is user selectable in ranges from 26 to 120 seconds, depending on the specific device. The sampling frequency of each device can also be adjusted from 4 kHz to 12 kHz with an external resistor, giving the user greater flexibility in duration versus recording quality for each application. Operating voltage spans a range from 2.4 V to 5.5 V to ensure that the ISD1700 devices are optimized for a wide range of battery or line-powered applications.

The ISD1700 is designed for operation in either stand-alone or micro-controller (SPI) mode. The device incorporates a proprietary message management system that allows the chip to self-manage address locations for multiple messages. This unique feature provides sophisticated messaging flexibility in a simple, push-button environment. The devices include an on-chip oscillator (with external resistor control) , microphone preamplifier with Automatic Gain Control (AGC) , an auxiliary analog input, anti-aliasing filter, Multi-Level Storage (MLS) array, smoothing filter, volume control, Pulse Width Modulation (PWM) Class D speaker driver, and current output.





Light Effects and Sound Effects Arduino Nano shield, shield contains 11 LEDs ,one buzzer and INA198 current measurement , shield can be used to develop various projects like LED Bar-graph Volt Meter, Bar-Graph Current Meter, LED light effects, Warning light and sound.

Download Data Sheet INA198 Current Sensor

  • Supply 5V DC
  • 11 LEDS Connected to D2-D12 Digital Pins Of Arduino Nano
  • Buzzer Connected to Digital Pin D13 to Arduino


 Note : Don’t populate parts showan in doted box








int led2 = 2; // LED connected to digital pin 2
int led3 = 3; // LED connected to digital pin 3
int led4 = 4; // LED connected to digital pin 4
int led5 = 5; // LED connected to digital pin 5
int led6 = 6; // LED connected to digital pin 6
int led7 = 7; // LED connected to digital pin 7
int led8 = 8; // LED connected to digital pin 8
int led9 = 9; // LED connected to digital pin 9
int led10 = 10; // LED connected to digital pin 10
int led11 = 11; // LED connected to digital pin 11
int led12 = 12; // LED connected to digital pin 12
int led13 = 13; // BUZZER connected to digital pin 13

void setup()
pinMode(led2, OUTPUT); // sets the digital pin as output LED
pinMode(led3, OUTPUT); // sets the digital pin as output LED
pinMode(led4, OUTPUT); // sets the digital pin as output LED
pinMode(led5, OUTPUT); // sets the digital pin as output LED
pinMode(led6, OUTPUT); // sets the digital pin as output LED
pinMode(led7, OUTPUT); // sets the digital pin as output LED
pinMode(led8, OUTPUT); // sets the digital pin as output LED
pinMode(led9, OUTPUT); // sets the digital pin as output LED
pinMode(led10, OUTPUT); // sets the digital pin as output LED
pinMode(led11, OUTPUT); // sets the digital pin as output LED
pinMode(led12, OUTPUT); // sets the digital pin as output LED
pinMode(led13, OUTPUT); // sets the digital pin as output BUZZER

void loop()
digitalWrite(led2, HIGH);
digitalWrite(led2, LOW);
digitalWrite(led3, HIGH);
digitalWrite(led3, LOW);
digitalWrite(led4, HIGH);
digitalWrite(led4, LOW);
digitalWrite(led5, HIGH);
digitalWrite(led5, LOW);
digitalWrite(led6, HIGH);
digitalWrite(led6, LOW);
digitalWrite(led7, HIGH);
digitalWrite(led7, LOW);
digitalWrite(led8, HIGH);
digitalWrite(led8, LOW);
digitalWrite(led9, HIGH);
digitalWrite(led9, LOW);
digitalWrite(led10, HIGH);
digitalWrite(led10, LOW);
digitalWrite(led11, HIGH);
digitalWrite(led11, LOW);
digitalWrite(led12, HIGH);
digitalWrite(led12, LOW);
digitalWrite(led13, HIGH);
digitalWrite(led13, LOW);



20Amps H-Bridge DC Motor Driver with Current and Fault Feedback Using IR2104-IR2101 IRFP4468

H-Bridge has been designed around IR2104 IC from international Rectifier, The board has been made mainly for DC-Motor Driver application, the driver can handle load up to 20 Amps, I have tested this board with 90V DC supply. The circuit uses N Channel IRFP4468 MOSFETS from international rectifier. MOSFET required large size heat sink.   Board has shunt resistor and signal conditioning circuits to provide voltage proportional to current passing through load. Comparator provides fault output, normally fault output is high goes low when its detect the over current passing through output..


  • Motor DC Supply 12V To 90V DC (Screw Terminal Connector)
  • Logic Supply 12V DC
  • Load 20 Amps (Screw Terminal Connector)
  • Fault Output Normally High, Goes Low When Over Current/Short Occurs
  • Current Feedback Output 200mv/1Amp ( If R5 Current Sense 0.01E)
  • Header Connector for Inputs (7 Pin Header Connector)
  • On Board Shunt Resistor for Current feedback
  • PWM Frequency 10 to 20 KHz
  • Duty Cycle 0-99%
  • Logic Pins support 3.3V, 5V, 12V (Inputs and PWM)


  • CN1 Supply Input
  • CN3 Logic Inputs, Current Feedback Output
  • CN2 Motor/Load Connections

CN3 Connections

Pin 1 Load Supply, Pin 2 GND, Pin 3 12V Gate Driver Supply, Pin 4 Input-1, Pin 5 SD1 Shutdown Input ( If IR2104 Used), Pin 6 Input 2, Pin 7 Shutdown Input ( If IR2104 Used), Pin 8 GND, Pin 9 Current Feed Back Output, Pin 10 Fault/Over Current Output, Pin 11 5V DC Output, Pin 12 Voltage Feedback Output


















A project has been designed around Holtek,s HT8970 voice echo IC.  Project can be used in various audio systems karaoke, toys, Animatronics, shows, displays, exhibitions, and sound equipment’s. The HT8970 is an echo/surround effect processor. It is designed for various audio systems including karaoke, television, sound equipment’s, etc. The chip consists of a built-in pre-amplifier, VCO or Voltage Control OSC, 20Kb SRAM, A/D and D/A converters as well as delay time control logic. The HT8970 chip echo processor IC utilizing CMOS technology. Which accept analog audio input signal, a high sample rate ADC transfer the analog signal into a bit stream then storage to internal  RAM, after processing the bit stream will de-modulate by DAC and low pass filter. Overall delay time is determined by internal VCO clock frequency, and user can easy to change the VCO frequency by trimmer pot. Jumper J1 provided to select the Microphone input or External audio signal input, CN1 Audio Signal input, PR1 Audio signal level adjust, PR2 output audio signal adjust, PR3 sound delay adjust,




  • Supply Input 5V DC
  • Onboard MIKE and Aux audio input ( Dual Option Selecting using Jumper)
  • MIKE and Aux  Selection via jumper
  • Input/MIKE signal level adjustable using Trimmer Potentiometer
  • It works in two modes – echo or surround
  • On Board Output signal level adjust Trimmer Pot
  • Onboard Trimmer Pot  for Sound Delay Adjust
  • Onboard LED for Power Supply Indicator
  • Four mounting holes of 3.2 mm
  • PCB dimensions 79 mm x 70 mm







Type K Thermocouple Sensor Amplifiers with Cold Junction Compensation Using AD595-AD594

The sensor project is based on AD595 IC from Analog devices.  AD595 is a complete instrumentation amplifier and thermo-couple cold junction compensator on a monolithic chip. It combines an ice point reference with a pre-calibrated amplifier to produce a high level (10 mV/°C) output directly from a thermo-couple signal. Pin-strapping options allow it to be used as a linear amplifier-compensator or as a switched output set point controller. It is amplify its compensation voltage directly, thereby converting it to a stand-alone Celsius transducer with a low impedance voltage output. The AD595 includes a thermo-couple failure alarm that indicates if one or both thermo-couple leads become open. The alarm output has a flexible format which includes TTL drive capability.

NOTE : Refer AD595 Data sheet for supply input and other information, The circuit works with single supply, same board also support AD594 IC which can support type J sensor.


  • Supply 15V DC
  • Supports Type K Thermocouples
  • Provides 10 mV/Centigrade

Download PDF Schematic


What is Thermocouple??

A thermocouple is an electrical device consisting of two dissimilar electrical conductors forming electrical junctions at differing temperatures. A thermocouple produces a temperature-dependent voltage as a result of the thermoelectric effect, and this voltage can be interpreted to measure temperature. Thermocouples are a widely used type of temperature sensor

What is Type K Thermocouple Sensor??

Type K Thermocouple (Nickel-Chromium / Nickel-Alumel): The type K is the most common type of thermocouple. It’s inexpensive, accurate, reliable, and has a wide temperature range. Type K thermocouples usually work in most applications as they are nickel based and exhibit good corrosion resistance. It is the most common sensor calibration type providing the widest operating temperature range. Due to its reliability and accuracy the Type K thermocouple is used extensively at temperatures up to 2300°F (1260°C). This type of thermocouple should be protected with a suitable metal or ceramic protection tube, especially in reducing atmospheres. In oxidizing atmospheres, such as electric furnaces, tube protection is not always necessary when other conditions are suitable; however, it is recommended for cleanliness and general mechanical protection. Type K will generally outlast Type J because the JP wire rapidly oxidizes, especially at higher temperatures.

Type K Thermocouple Range

  • Thermocouple grade wire, –454 to 2,300F (–270 to 1260C)
  • Extension wire, 32 to 392F (0 to 200C)


AD595 Output Voltages


Various Type K Temperature Sensors



Optical Reflective Line Sensor for Robotics and No Contact Surface Sensing QRE1113

The sensor circuit helps to sensing the line for robotics application and  no contact surface sensing. The mini line sensor provides analog voltage output and can work with 3.3V and 5V DC. Analog output voltage is proportional to IR reflected to the senor. Resistor R1 controls the current  to IR LED, R2 provided as pull up resistor. Sensor contains Infra-Red led and photo transistor detector.

Download PDF Schematic


Schematic Line Sensing Sensor QRE1113



PCB layout QRE1113 Optical Sensor




Pin Configuration

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

This method can be used to control any series of digital outputs that depends
on an analog input.

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() {
// read the potentiometer:
int sensorReading = analogRead(analogPin);
// 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);



High Voltage Low EMI Power Supplies for AC Inverters and VF Drives, Brush-Less Motor Drivers

The high voltage high current low EMI, power supply circuit published here is intend use for AC inverters and VF drives,AC servo driver, brushless dc motor driver, IPM (Intelligent Power Module) , high voltage DC brushed motor drivers and various other circuit required high voltage DC supply.   Capacitor has been selected for AC power input up to 250V AC however capacitor voltage and value can be alter as per DC output required.  Bridge rectifier can handle current up to 25Amps and need large heat sink for full load. Onboard transformer used as EMI fliter.

  • AC Supply input up to 250V V AC
  • Maximum DC Output 400V DC and 10Amps.
  • DC Supply Output will depend on input supply
  • Fuse for Short circuit and over current protection
  • Fuse as per your application requirement Maximum 10Amps Fuse
  • NTC provided for inrush current
  • DC Bus has bleeding resistor








Heat Activated Cooling Fan Controller Circuit Using LM393-LM358 & LM35 Temperature Sensor

Heat activated cooling fan controller ( Thermal Activated Cooling Fan Driver Circuit) is a simple project which operates a Brush-Less fan when the temperature in a particular area goes above a set point, when temperature return normal, fan automatically turns off. The project is built using LM358 Op-amp ( Use LM393 instead for good performance) ,  and LM35 temperature Sensor. Project required 12V DC supply and can drive 12V Fan. This project is useful in application like Heat sink temperature controller, PC, heat sensitive equipment, Power supply, Audio Amplifiers, Battery chargers, Oven.

The SMD SO8 LM35 used as temperature sensor, LM358 act as comparator provides high output when temperature rise above set point, high output drive the Fan trough driver transistor. The LM35 series are precision integrated-circuit temperature devices with an output voltage linearly-proportional to the Centigrade temperature. The LM35 device has an advantage over linear temperature sensors calibrated in Kelvin, as the user is not required to subtract a large constant voltage from the output to obtain convenient Centigrade scaling. The LM35 device does not require any external calibration or trimming to provide typical accuracies of ±¼°C at room temperature. Temperature sensing range 2 to 150 centigrade. LM35 provides output of 10mV/Centigrade.

NOTE :  It is  advisable to use LM393 Comparator instead of LM358 as it will provide better results.

  • Supply 12V DC 1Amps
  • Fan 12V DC , 500mA
  • Range : 2 °C to 150 °C
  • Open Collector Output
  • It can drive PC fan
  • Onboard preset to set the Fan trigger level
  • Onboard Power LED
  • Onboard Output LED
  • Output Driver Transistor
  • Header Connector for Supply and Fan
  • PCB dimensions 59.85 mm x 12.70 mm

Watch Video of the project available here







LM35 Temperature Sensor

The LM35 series are precision integrated-circuit temperature devices with an output voltage linearly-proportional to the Centigrade temperature. The LM35 device has an advantage over linear temperature sensors calibrated in Kelvin, as the user is not required to subtract a large constant voltage from the output to obtain convenient Centigrade scaling. The LM35 device does not require any external calibration or trimming to provide typical accuracies of ±¼°C at room temperature and ±¾°C over a full −55°C to 150°C temperature range. Lower cost is assured by trimming and calibration at the wafer level. The low-output impedance, linear output, and precise inherent calibration of the LM35 device makes interfacing to readout or control circuitry especially easy. The device is used with single power supplies, or with plus and minus supplies. As the LM35 device draws only 60 µA from the supply, it has very low self-heating of less than 0.1°C in still air. The LM35 device is rated to operate over a −55°C to 150°C temperature range, while the LM35C device is rated for a −40°C to 110°C range (−10° with improved accuracy). The LM35-series devices are available packaged in hermetic TO transistor packages, while the LM35C, LM35CA, and LM35D devices are available in the plastic TO-92 transistor package. The LM35D device is available in an 8-lead surface-mount small-outline package and a plastic TO-220 package.


LM358 Op-Amp

These devices consist of two independent, high-gain frequency-compensated operational amplifiers designed to operate from a single supply or split supply over a wide range of voltages.

LM393 Comparator

These devices consist of two independent voltage comparators that are designed to operate from a single power supply over a wide range of voltages. Operation from dual supplies also is possible as long as the difference between the two supplies is 2 V to 36 V, and VCC is at least 1.5 V more positive than the input common-mode voltage. Current drain is independent of the supply voltage. The outputs can be connected to other open-collector outputs to achieve wired-AND relationships.

LM293A devices are characterized for operation from −25°C to +85°C. The LM393 and LM393A devices are characterized for operation from 0°C to 70°C. The LM2903, LM2903V,

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