EK Technologies

Interfacing LM35 temperature sensor with PIC microcontroller An LM35 temperature sensor senses the temperature and produces Analog signals which is fed to a microcontroller which interprets the result. The microcontroller used here contains an Analog to Digital Converter (ADC) which receives the signals from the LM35 and produces a corresponding digital signal and the value of the temperature displayed on an LCD. Application: Room temperature control Egg incubator Dryers e.g. cocoa dryers, Green agriculture, etc. Materials: An LM35 A PIC 16F877A Two relays 2 transistors BC549 2 protective diodes (fly-back diodes) A Fan A heater A 16x2 LCD Supply DC 5/12V, AC 230V Circuit diagram of LM35 temperature sensor interface with microcontroller The circuitry is shown below Operation Lets control the temperature such that if the temperature is less than 25 degree Celsius, the heater is put ON and the fan OFF. If the temperature is about 25 degree Celsius, the...

Interfacing a relay circuit with a PIC microcontroller We are going to see how to interface a relay to a PIC micro controller. But before that, you need to know what is a relay. A relay is a switching device which permits the switching of a load in a circuit or to a supply. The advantage of using a relay is due to the fact that, this device can permit the switching of high loads in circuits. Before interfacing a relay in a circuit, the relay must be chosen to suit the supplying circuit and the required load. For example, th ere are relays which operate at 5V, 6V, 12V, etc. and having a maximum load current and voltage rating. Materials PIC 16F877A, 5V relay, 5V DC source, 1 BC547 transistor, 1 diode 1N4148, 230V AC load (heater), 230V AC source, 8MHz Crystal Oscillator, 2 ceramic capacitors, 2 resistors, 1 push button. Circuit diagram of relay with microcontroller The circuit diagram is shown below. The relay is connected to PORTC of the microcontroller at Pin...

What is Touch potential? You often came across the term step and touch potential, but you never new what's all about. Grab it now. Touch potential is the potential generated across a conductive body or object to the earth, when the conductive body contacts or touches a live wire. So, current flow through the conductive body from the live wire to the earth.  This can occur due to earth failure and inappropriate earthing in an installation. Other causes exist. To illustrate this, we are going to see some common examples. How touch potential is generated 1) A person touching a poorly earthed conductive part during earth failure. E.g touching the metallic part of towers, machines, etc during earth failure. 2) Live TV media antenna buses mistakenly touching live wires in transmission lines. 3) Excavators and lifters mistakenly touching a transmission line Those are just some few examples of how touch potential is generated. So, electrical tec...

What is Step Potential This is the potential generated between the feet of a person or animal closer to the surface or area of an earthed rod/wire/object carrying current. During earth faults, high amount of current flows to the ground and the nearby ground surface beside the earthed object. If a person is standing within the area closer to the grounded object, a potential can be generated between the feet (foot to foot) and the difference in potential causes current to flow through the body which is dangerous. So, the wider the distance between the feet (foot to foot), the higher the potential difference and the higher the current being induced. The smaller the distance between feet, the lesser the potential different and the smaller the induced current into the body. Equipotential points have zero potential different. So, with the feet being tight together, the points are at the same potential (equipotential point). This is the reason why birds are not electrocuted when they stan...

Types of single phase induction motors| starters The different types of single phase induction motors are identified or named by their starting methods. They include: 1)Split – phase Induction Motor 2) Capacitor – Start Motor 3) Permanent – Split Capacitor Motor 4) Capacitor - Start Capacitor - Run motor 1) Split-phase induction motor The split phase induction motor also called the inductance start motor. The stator has two windings namely the main winding and the auxiliary winding which are displaced in space by 90 degrees. When the motor is supplied, the rotor accelerates and when it reaches about 75% of the synchronous speed, the centrifugal switch disconnects the starting winding. The split phase induction motor is also known as the resistance start motor when a high resistance is added in series to the starting winding.  And the operation is the same as the one above. 2. Capacitor start motor The capacitor-start motor is similar to the split phase i...