In this article we learn how to design and build a solid state contactor circuit using triacs for operating heavy duty loads like submersible borewell pump motors with high reliability, and without any concerns about wear and tear issue or long term degradation issues of the contactor unit. What is a Contactor A contactor is […]
Automatic PIR based Solar Home Lighting
The post explains a simple circuit using PIR, LDR for making an automatic solar LED lamp which can be used for illuminating your home automatically at sunset, and only in the presence of a human member in the premise. By SS Kopparthy Introduction Here, in this article, a simple yet useful and improved version of the […]
How to Make a Simple Milliohm Tester
I wanted a milliohm tester circuit that could be used to measure resistance on printed circuit boards to track down shorted components. I looked at several designs and combined several ideas into this project. By Henry Bowman Simulation and Working Referring to the schematic, the milliohm tester is powered by two 9 volt dry cells. […]
Using Microwave Oven Parts to build a Soldering Iron Heat Controller
In this post we learn how to scavenge discarded microwave oven parts for making a useful soldering iron heat controller circuit which can then be used for maintaining controlled heat over a connected soldering iron tip ensuring safe soldering operations, that may be quite crucial and handy if you are working with SMD parts. By […]
Simple Transformer Winding Tester
This test set is primarily designed to test step-down, step-up transformers, for open and shorted windings. It can determine if the device under test has a low resistance to ac current. It can also measure the dc current resistance in ohms. By Henry Bowman Introduction The test set uses a 16 VAC, 60hz signal to […]
Simple MOSFET Tester and Sorter
This simple MOSFET tester does a quick job of testing both enhanced mode type N and P-channel mosfets. It checks for shorts between gate, drain and source. Designed By: Henry Bowman It also distinguishes between N and P-channel mosfets. Once the connections are correctly made to the mosfet, all testing is done without reversing connections. […]
Cell Phone Ring to Flashing Lamp Indicator for People with Hearing Loss
The post explains a simple sound to flashing lamp circuit which can be used for facilitating people with hearing loss, so that they are able to visualize a distant cell phone rings through flashing of a lamp, and immediately understand regarding an incoming call in their cell phone. The following explanation and the circuit design […]
400V 40A Darlington Power Transistor Datasheet Specifications
In this post we investigate the datasheet and technical specifications of a 400V, 40A (ampere) power Darlington transistor MJ10022 and MJ10023, and also learn the main features of the device. We mostly find it difficult when it comes to finding a BJT with extreme voltage and current specifications such as with a 400V and 40 […]
Make this IR Remote Control Range Extender
In this post we will learn how to increase or extend the range of an ordinary infra red or IR remote control through a 433MHz RF remote control system. IR Range Extender Concept The idea of this circuit is to feed the IR data from an IR transmitter into the transmitter input of an RF […]
Introduction to I2C LCD Adapter Module
In this post we are going take a look at “I2C” or “IIC” or “I square C” based LCD adapter module, which will reduce wire connections between Arduino and LCD display to just 2 wires, also saving tons of GPIO pins for other sensors / drives etc. By Girish Radhakrishnan Before we discuss about I2C […]
Simple Transistor Diode Tester
In this post we learn how to make a simple yet efficient transistor/diode tester circuit, that will not only test the quality of a BJT, but will also help to identify whether it is is an NPN or a PNP. The circuit was designed and contributed by Mr. Henry Bowman. Simulation and Working Referring to […]
3D Moon-Sphere LED Driver with Charger and Dimmer
In this post we learn how to build a homemade LED driver with dimmer and charger circuit for illuminating a 3D moon from a 5V USB source. The idea was requested by Mr. John Sweden. Specifications and Features I’ve been a visitor to your website for many years and wonder if I may ask your […]
How to Make a RFID based Attendance System
In this post we are going to construct a RFID based attendance system, which can record attendance of 12 students / staffs for a given time window and this system can record up to 255 attendances per person. By Girish Radhakrishnan What is RFID Attendance System We don’t need any introduction regarding the RFID based […]
Microprocessor based Automatic School/College Bell System
In this post we are going to construct an automatic school bell/college bell system using Arduino, 16 x 2 display and real time clock module. You can program this project to ring the bell up to 16 times a day at your preferred hour and minute. The length of the bell ring can be programmed […]
Build this Mosquito Bat without Battery
This simple homemade mosquito swatter bat neither requires a circuit nor a battery for the operation. The entire design works using a single high voltage capacitor and through quick charging from mains AC socket. (Designed by me) Introduction In a few of my earlier posts I have discussed how to make mosquito zappers using the […]
Patient Drip Empty Warning Indicator
In this post we will learn about a simple mechanism, and a circuit which will enable a patient’s IV drip bottle system to sound an alarm whenever it gets almost empty, and needs a replacement. The warning circuit will help doctors and the concerned employees to concentrate on other important matters while the drip systems […]
What is Constant Current Source – Facts Explained
In this post we try to analyze what is constant current source and how it affects a load, or how it may be used with a load correctly for achieving the most efficient results. The following discussion between me and Mr. Girish will clearly explain what is CC or how constant current operates. How a […]
How to Repair a Switch-Mode-Power-Supply (SMPS)
In this post we try to diagnose a burnt SMPS circuit and try to troubleshoot and repair the circuit. The shown unit is a cheap readymade Chinese make SMPS circuit. This article is written as per the request made by Mr. Kesava. My SMPS got Burnt The below attachment is 12v 1.3 amps SMPS for […]