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,

L298 Dual/Single DC Motor Driver Shield Arduino Nano

Dual Motor L298 H-Bridge Control project can control two DC motors OR single motor with 2X current. The circuit is designed around popular dual H-Bridge L298 from ST. This board can be configured to drive a single motor with high current rating also. This can be achieved with the help of jumpers on the board. An onboard 5V regulator can take a maximum of 18V of DC input. Should you wish to drive this board with higher voltage then 18V, you will need to connect a external 5V regulated source to the logic circuit. For this you will need to remove J-5V. This board can fit in any small toy or robot due to small size and very low profile. L298 IC is mounted under the PCB in horizontal position to make board small and low profile to fit any small robot. On board 5V regulator can be used to power up external Micro-Controller board as well as internal logic supply.




Motor supply: 7 to 46 VDC
Control Logic Input: Standard TTL logic level
Output DC drive to motor: up to 2 A each (Peak)
On Board 5V Regulator (Close J-5V to Use On Board 5V Regulator)
Enable and direction control pins available
External Diode Bridge for protection
Heat-sink for IC
Power-On LED indicator
Header Connector for Inputs and PWM
On Board PCB Solderable Jumpers for Enable
Screw terminal connector for easy input supply (PWR) / output (Motor) connection


L298 to Arduino Nano Connections>I1>D4,I2>D5,E1>D6,I3>D9,I4>D10,E2>D11




4 Channel Relay Driver Shield For Arduino Nano



Quad Channel Relay Board Arduino Nano Shield is a simple and convenient way to interface 4 relays for switching application in your project.


     Input supply 12 VDC @ 170 mA

     Output four SPDT relay

     Relay specification 5 A @ 230 VAC

     Trigger level 2 ~ 5 VDC from Arduino I/O D2,D3,D4,D5 Digital Lines

     Power Battery Terminal (PBT) for easy relay output and aux power connection

     LED on each channel indicates relay status

Applications: Robotics, Electronics projects, Industrial controls, Microwaves Oven, Fans, DC Motor, AC Lamp, Solenoids Remote Controls etc.

Relay Load (Contact Capacity of Relay)


  •     7 A @ 230-250 VAC
  •     10 A @ 120 VAC
  •     10 A @ 24 VDC
  •     CN1 – CN4 Connector : Relay 1 to 4 (S1 to S4) Output (Normally Open/Normally Close)
  •     CN5 Connector : Control Signal Input, Trigger 2 to 5 VDC and Supply Input 12 VDC
  •     D2,D4,D6,D8 : Relay On/Off LED Indication
  •     CN6 , CN7 12V DC Input





Mini DC Motor Speed and Direction Controller for Low Voltage Motors Using L293D & 555 Timer


Project has been designed around L293 H-Bridge for Bidirectional motor operations, & 555 Timer IC which has been used as PWM generator for speed control. L293 is capable of continuous output current 600mA. Operating voltage 5V DC. Specially designed for low voltage Mini motors. Great control on speed via onboard preset, while direction is controlled by changing jumpers settings. PWM Duty cycle range 20% to 90% . Great kit can be used in science projects, toys, mini motor speed controllers, robotics, model-making.

DC Motor Speed and direction controller project based on L293D H-Bridge and 555 Timer IC. 555 Generate PWM and L293D works as output driver. The 293D provides bidirectional drive current up to 600mA a voltage from 5V to 12V. L293D includes the output clamping diodes for protections.


  • Supply 5 to 12 V
  • Inhibit facility/enable
  • PWM Frequency 5KHz Maximum
  • High Noise immunity
  • Over temperature protection
  • Capable of delivering output current up to 600 mA per channel
  • The control/interface lines are accessible with Berg connector
  • Header connector for motor and supply connection
  • PR1 : Preset Speed Adjust
  • SW1 : 3Pin Jumper and Closer for Direction change
  • CN1 : DC Motor Supply input 5V to 12V DC





The L293 and L293D devices are quadruple high-current half-H drivers. The L293 is designed to provide bidirectional drive currents of up to 1 A at voltages from 4.5 V to 36 V. The L293D is designed to provide bidirectional drive currents of up to 600-mA at voltages from 4.5 V to 36 V. Both devices are designed to drive inductive loads such as relays, solenoids, DC and bipolar stepping motors, as well as other high-current/high-voltage loads in positive-supply applications.

Each output is a complete totem-pole drive circuit, with a Darlington transistor sink and a pseudo- Darlington source. Drivers are enabled in pairs, with drivers 1 and 2 enabled by 1,2EN and drivers 3 and 4 enabled by 3,4EN.



Quadrature Encoder to Clock and Direction Signal Converter Using LS7084/LS7184

The quadrature LS7084/LS7184 Module is a CMOS quadrature clock converter. Quadrature clocks derived from optical or magnetic encoders, when applied to the A and B inputs of the LS7084 are converted to strings of a Clock and an Up/down direction control. These outputs can be interfaced directly with standard Up/Down counters for direction and position sensing of the encoder.

J1 Jumper input selects between x1 and x4 modes of operation. A high level selects x4 mode and a low-level selects the x1 mode. In x4 mode, an output pulse is generated for every transition at either A or B input. In x1 mode, an output pulse is generated in one combined A/B input cycle.

Resistor R7-RBIAS (Pin 1) Input for external component connection. A resistor connected between this input and VSS adjusts the output clock pulse width (Tow). For proper operation, the output clock pulse width must be less than or equal to the A, B pulse separation (TOW £ TPS).



  • Supply 5V DC
  • +4.5V to +10V operation (VDD – VSS)
  • On Board Power LED
  • J1 Encoder pulse multiplication ( Jumper JL Close =1X, Jumper JH Close = X4)
  • Header Connector for Encoder Interface
  • X1 and X4 mode selection
  • Programmable output clock pulse width
  • On-chip filtering of inputs for optical or magnetic encoder applications.
  • TTL and CMOS compatible I/Os
  • Up to 16MHz output clock frequency


Note : Circuit uses LS7084 IC , which is CMOS IC and working voltage range 4.5V to 10V and it has two scale up  range.X1 and X4. The board can be used with LS7184 which can work with lower supply range 3.3V to 5V and it can provide X1,X2,X4 resolution, refer data sheet of LS7184 for more information.








Note: Check Graph for R7- Bias Selection





What is Quadrature Encoder?

The most common type of incremental encoder uses two output channels (A and B) to sense position. Using two code tracks with sectors positioned 90 degrees out of phase, the two output channels of the quadrature encoder indicate both position and direction of rotation. If A leads B, for example, the disk is rotating in a clockwise direction. If B leads A, then the disk is rotating in a counter-clockwise direction.

By monitoring both the number of pulses and the relative phase of signals A and B, you can track both the position and direction of rotation.

Some quadrature encoders also include a third output channel, called a zero or index or reference signal, which supplies a single pulse per revolution. This single pulse is used for precise determination of a reference position.

How Quadrature Encoder Works?

The code disk inside a quadrature encoder contains two tracks usually denoted Channel A and Channel B. These tracks or channels are coded ninety electrical degrees out of phase, as indicated in the image below, and this is the key design element that will provide the quadrature encoder its functionality. In applications where direction sensing is required, a controller can determine direction of movement based on the phase relationship between Channels A and B. As illustrated in the figure below, when the quadrature encoder is rotating in a clockwise direction its signal will show Channel A leading Channel B, and the reverse will happen when the quadrature encoder rotates counterclockwise.

Apart from direction, position can also be monitored with a quadrature encoder by producing another signal known as the “marker”, “index” or “Z channel”. This Z signal, produced once per complete revolution of the quadrature encoder, is often used to locate a specific position during a 360° revolution.

Constant Current Laser Diode Driver Using OPA2350 OP-AMP

The voltage-controlled current source circuit can be used to drive a constant current into a signal or pump laser diode. This simple linear driver provides a cleaner drive current into a laser diode than switching PWM drivers. The basic circuit is that of a Howland current pump with a current booster (Q1) on the output of a R-R CMOS OPA2350 op amp (U1). Laser diode current is sensed by differentially measuring the voltage drop across a shunt resistor (RSHUNT) in series with the laser diode. The output current is controlled by the input voltage (VIN) that comes from Trim pot PR1.


  • Supply 3,3V DC
  • Load Up to 300mA
  • PR1 Trimpot Current Adjust



Download Data Sheet OPA2350




4 Channels Optically Isolated I/O Board Using 6N137 Optocoupler

4 Channel Opto isolated board has been designed around 6N137 Opto-coupler, the 6N137 optocoupler is designed for use in high-speed digital interfacing applications that require high-voltage isolation between the input and output. Applications include line receivers, microprocessors or computer interface, digital programming of floating power supplies, motors, and other control systems.

The 6N137 high-speed optocoupler consists of a GaAsP light-emitting diode and an integrated light detector composed of a photodiode, a high-gain amplifier, and a Schottky-clamped open-collector output transistor. An input diode forward current of 5 milliamperes will switch the output transistor low, providing an on-state drive current of 13 milliamperes (eight 1.6-milliampere TTL loads).

Note : For 3.3 Input Signal R1, R4, R7, R10 = 220E


  • Supply 5V DC
  • Input Signal : 5V DC TTL
  • Header Connectors for Inputs & Outputs
  • D1 Power LED





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