Month: May 2013


The following post describes a simple low battery indicator circuit by using just two inexpensive NPN transistors. The main feature of this circuit is its very low stand by current consumption.


We can also make a low battery indicator circuit using a 741 IC and a 555 IC, which are no doubt outstanding with their abilities of detecting and indicating low battery voltage thresholds.

However the following post relates yet another similar circuit which is much cheaper and employs just a couple of NPN transistors for producing the required low battery indications.

The main advantage of the proposed two transistor low battery indicator circuit is its very low current consumption compared to the IC counterparts which consume relatively higher currents. A IC 555 would consume around 5mA, a IC741 around 3 mA, while the present circuit would just consume around 1.5mA current.

Thus the present circuit becomes more efficient especially in cases where Continue reading


A teenager specializing in DIY lasers has apparently made his own version of a functional Star Wars lightsaber. In a video demonstration, he uses the device to light things on fire — paper, a match, even a ping-pong ball.


DIY laser enthusiast Drake Anthony describes himself as a teenager in Eureka, Illinois, who has been building lasers and electronics since he was 12. Online he goes by the name Styropyro and recently showed off his homemade lightsaber. Anthony described the parts as a 9 mm 450 nm laser diode from a DLP projector — the digital light processing kind you see in classrooms — and two 18650 lithium ion batteries usually found in laptops.

He measures the output as an “insane 3W” Continue reading


Quadrotor drones are doing a lot these days: they’re helping to save the elephants, rescue drowning victims. While these important duties naturally suggest a certain level of independence, the drones aren’t entirely autonomous because they still require human pilots to control their maneuvers.


They have proposed a quadrotor drone that uses artificially intelligent algorithms and depth motion-tracking cameras to follow a person from a safe distance and/or film the encounter. One method for doing so would involve the drone tracking a specific graphic on a user’s t-shirt.

One of Pet Drone’s main applications could be for BASE jumpers and other extreme athletes who want to film stunts that are out of range of human controlled drones. But that’s not all. Continue reading


Most of us are more comfortable with 1, 2, 3, 4… rather than 001, 010, 011, 100. We mean to say that we will need a decimal coded output in many cases rather than a raw binary output. We have many counter ICs available but most of them produce binary data as an output. We will again need to process that output by using decoders or any other circuitry to make it usable for our application in most of the cases.

Let us now introduce you a new IC named IC 4017. It is a CMOS decade counter cum decoder circuit which can work out of the box for most of our low range counting applications. It can count from zero to ten and its outputs are decoded. This saves a lot of board space and time required to build our circuits when our application demands using a counter followed by a decoder IC. This IC also simplifies the design and makes debugging easy.

Pin-Diagram-of-4520 Continue reading



Here is an art project for you to try out. In this article we shall learn the design and working of the circuit Circling LEDs. In this, we have eight LEDs which glow one after the other to form a circling effect. My intention in publishing this circuit is not just to make some art work with electronics but also to illustrate the working principle and circuit design using IC 555 in astable mode, 4017 counter and to explain the related concepts.

IC4017 Circuit Schematic:

circling-LEDs Continue reading


passive infrared sensor (PIR sensor) is an electronic sensor that measures infrared (IR) light radiating from objects in its field of view. They are most often used in PIR-based motion detectors.

Different Types Of PIR Sensors :

  • Multi-Fresnel lens type of PIR
  • PIR motion detector housing with cylindrical faceted window. The animation highlights individual facets, each of which is a Fresnel lens, focusing light on the sensor element underneath.

  • PIR front cover only (electronics removed), with point light source behind, to show individual lenses.

  • PIR with front cover removed, showing location of pyroelectric sensor (green arrow).

Operating principles

All objects with a temperature above absolute zero emit heat energy in the form of optical radiation (light). Usually this light is invisible to the human eye because body temperature radiates at infrared wavelengths, but it can be detected by electronic devices designed for such a purpose. Continue reading


The sensors could be utilized as a part of measuring the radiation temperature without any contact. For different radiation temperature ranges various filters are available. An infrared (IR) sensor is an electronic device that radiates or locates infrared radiation to sense some part of its surroundings. They are undetectable to human eyes.


An infrared sensor could be considered a Polaroid that briefly recalls how an area’s infrared radiation shows up. It is very regular for an infrared sensor to be coordinated into movement indicators like those utilized as a feature of private or business security systems. An IR sensor is shown in figure; basically it has two terminals positive and negative. These sensors are undetectable to human eyes. Continue reading


Famous among the DIY electronics community for their single-board microcontroller, Arduino recently launched a new wheeled robot at the 2013 Bay Area Maker Faire.

Designed with Complubot, a four-time Robocup Junior champion in robotic soccer, the Arduino Robot, with its self-contained platform, will allow tinkerers of all stripes to explore their robotic whims with endless hours of interactive play and experimentation.

As the first official Arduino on wheels, the hockey puck-shaped robot includes two processors, one on each of its two boards: the motor board, which obviously controls the wheel motors, and a control board, which reads sensors and makes decisions on operations.

Essentially, the top and bottom surfaces of the robot are full Arduino boards that are programmable with the Aduino IDE software.

“Programming the robot is similar to the process with the Arduino Leonardo” microcontroller. “Both processors have built-in USB communication, eliminating the need for a secondary processor. This allows the Robot to appear to a connected computer as a virtual (CDC) serial / COM port.”

Every element of the platform — the hardware, software and documentation — is open-source and available like all other Arduino products. This allows users to modify the software and build unique hardware on top of it, making the platform perfect for novices and more seasoned roboticists to build interactive machines of their own design.

Credit: Arduino


LED are known to have a very wide range of applications in the lighting field and are also known to have very high efficiency and longer life when compared to CFL and incandescent bulbs, here we discuss a few interesting application of LED’s.

Here are two night lamp circuits using LEDs. One could be used as a night-vision clock and the other as a TV lamp. Both the circuits are AC operated and consume very little power. These are also protected against mains fluctuations. The night-vision lamp uses twelve LEDs arranged in the circular pattern of a wall clock, while the TV lamp uses 24 LEDs in prism format.

Fig. 1: Night-vision clock circuit

Source : Electronics For You
Fig.1 shows the circuit of night-vision clock. Capacitor C1 (0.22µF) reduces the Continue reading


This is a really innovative way to increase the efficiency in harnessing the Solar energy. Research suggests that if we are able to harness solar energy to a 90-100%  then using the energy harnessed in one day, we can run about one million cars powered by solar, but theoretically we are harnessing less than 10%.

Generally, solar panels are stationary and do not follow the movement of the sun. Here is a solar tracker system that tracks the sun’s movement across the sky and tries to maintain the solar panel perpendicular to the sun’s rays, ensuring that the maximum amount of sunlight is incident on the panel throughout the day. The solar tracker starts following the sun right from dawn, throughout the day till evening, and starts all over again from the dawn next day.

Fig. 1: Circuit of solar tracking system

Fig. 1 shows the circuit of the solar tracking system. The solar tracker comprises comparator IC LM339, H-bridge motor driver IC L293D (IC2) and a few discrete components. Light-dependent resistors LDR1 through LDR4 are used as sensors to detect the panel’s position relative to the sun. These provide the signal to motor driver IC2 to move the solar panel in the sun’s direction. LDR1 and LDR2 are fixed at the edges of the solar panel along the X axis, and connected to comparators A1 and A2, respectively. Presets VR1 and VR2 are set to get low comparator output at pins 2 and 1 of comparators A1 and A2, respectively, so as to stop motor M1 when the sun’s rays are perpendicular to the solar panel. 

When LDR2 receives more light than LDR1, it offers lower resistance than LDR1, providing a high input to comparators A1 and A2 at pins 4 and 7, respectively. As a result, output pin 1 of comparator A2 goes high to rotate motor M1 in one direction (say, anti-clockwise) and turn the solar panel.

When LDR1 receives more light than LDR2, it offers lower resistance than LDR2, giving a low input to comparators A1 and A2 at pins 4 and 7, respectively. As the voltage at pin 5 of comparator A1 is now higher than the voltage at its pin 4, its output pin 2 goes high. As a result, motor M1 rotates in the opposite direction (say, clock-wise) and the solar panel turns.

Fig. 2 Proposed assembly for the solar tracking system

Similarly, LDR3 and LDR4 track the sun along Y axis. Fig. 2 shows the proposed assembly for the solar tracking system.


3-d-printing-1Imagine that you’ve decided to organize your closet, but instead of measuring containers at a store to make sure they will work, you just go to your office, enter the measurements you want your containers to be, and print them out right there. Now imagine that you have to build a diorama of a famous Civil War battle for a project at school, and you use that same printer to construct all the soldiers, cannons and trees in perfect detail.

This technology may be closer than you think thanks to 3-D printing. 3-D printing is making it easier and faster to produce complex objects with multiple moving parts and intricate design, and soon it will be affordable enough to have at home.

Source : How Stuff Works

Continue reading


Are you confused on how to give a fresh new life to a broken CFL bulb, read on you’ll get the answer to this question here.

In this post i’m sharing a LED lamp circuit which can be mounted in a broken CFL bulb and can be  converted into a LED based power saving light. This is just a LED lamp circuit that can be operated from the mains voltage. A string of five LED is driven using a capacitive transformerless power supply. In the circuit 0.47uF/400V Polyester capacitor C1 reduces the mains voltage. R3 is a bleeder resistor which drains the stored charge from C1 when the AC input is switched OFF. Resistors R1 and R2 limits the inrush of current when the circuit is switched ON. Diodes D1 to D4 forms a bridge rectifier that rectifies the reduced AC voltage and C2 acts as a filter capacitor. Finally Zener diode D5 provides regulation and the LEDs are driven.

Here are some of the pictures of the LED lamp.



Components used :

  • 120 Ohm 1/2 Watt resistors [2]
  • 470k Ohm 1/4 Watt resistor [1]
  • 0.47uF, 400 V Polyster capacitor
  • IN4007 Diodes [4]
  • 47uF, 25V electrolytic capacitor
  • 16-18V 1W Zener diode [1]
  • Hi power LED’s. [ Here i have used 1W circular LED’s ]


The circuit board arrangement which i have built.


After assembling the Circuit board in the CFL bulb casing.


The LED arrangement on a laminate sheet.


The completely assembled, finished LED light.


My smart LED lamp in action.


Another close view of the illuminating LED’s.


1. Carefully remove the broken glass pieces of the CFL bulb.

2. Open the assembly carefully

3. Remove electronics and discard

4. Assemble the circuit in dot matrix PC or on a 1mm laminate sheet.

5. Cut a round laminate sheet with (scissor)

6. Mark the position of the 5 round holes on the sheet

7. Drill the holes to suit the LEDs to flush fit in the six holes

8. Use a dab of adhesive to keep the LED assembly in position

9. Close the assembly

10. Ensure the internal wiring does not touch each other

11. Now test on 230Volt AC Your nice compact table lamp / puja room lamp / passage lamp is ready for use.

For any queries related to this post, ask your questions in the comments section below.


Theme by Anders NorenUp ↑