Mutchus

4.2.1.1 Defects of a simple Electric Cell The practical value and performance of simple cells is limited by the following defects: (a)          Polarization In the reaction in the simple cell, hydrogen gas is evolved. It collects in bubbles around the positive electrode and-eventually insulate the positive electrode from the solution.  This  stops  the reaction. This process is known as polarization. It is minimized by use of a depolarizer.  This is a chemical which reacts with the hydrogen to produce water e.g. manganese dioxide. (b)          Local Action Impurities such as iron and lead embedded in the zinc  electrode  form small local cells. The impurity acts as the positive electrode and zinc as the negative. The formation of these local cells between the impurities and the zinc electrode is referred to as local action. It tends to wear the zinc electrod...

Function of Each Part of D.C Generator A D.C Generator consists of the following parts: 1.        Yoke or magnetic frame 2.        Pole cores and pole shoes 3.        Field windings 4.        Brushes and brush holders 5.        End covers 6.        Armature core 7.        Armature winding 8.        Commutator 9.        Shaft Fig 1. DC Generaotor Parts 1.        Yoke or magnetic frame: The outer most frame is known as Yoke. It is made of high permeability material possessing sufficient mechanical strength. Cast iron is used in small machines and cast steel or rolled steel is employed in large machines. The Yoke serves two fold as:                  (...

Most electric kettles do not produce a whistle and just switch off when they have boiled. Fitting a box of electronics directly onto an electric kettle (or even inside!) to detect when the kettle has boiled is obviously out of the question. The circuit shown here detects when the kettle switches off, which virtually all kettles do when the water has boiled. In this way, the electronics can be housed in a separate box so that no modification is required to the kettle. The box is prefer-ably a type incorporating a mains plug and socket.  In this application, the current flowing in coil L1 provides a magnetic field that actuates reed switch S1. Since the current drawn by the kettle element is relatively large (typically 6 to 8 amps), the coil may consist of a few turns of wire around the reed switch. The reed switch is so fast it will actually follow the AC current flow through L1 and produce a 100-Hz buzz. The switching circuit driven by the reed switch must, therefore, disregard t...

Weston (M.I) Type Frequency Meter Principle:  It is a moving iron instrument which operates on the principle of variation of impedance in an inductive circuit with variation of frequency. Weston Frequency Meter Construction: It consists of two coils A and B mounted perpendicular to each other. Each coil is divided into two sections. The connections are as shown in the above fig. The branch of coil has a resistance R 1 connected in the series with it while coil B has a reactance coil L 2 in series with it. Circuit of coil A is in parallel with a reactance coil L 1 while that coil B is in parallel with a resistance R 2 . The moving element is a soft iron needle. The needle is pivoted on a spindle which is also carries a pointer and damping vanes. There is no controlling torque. The series reactance L 0 acts to suppress higher harmonics in the current of instrument and therefore tends to minimize the waveform errors in its indication. Working: When the meter is connected across th...

Opto Coupler Opto coupler is a solid state component in which light emitter the light path and light detector are all enclosed within the component and cannot be altered externally. Usually infrared emitting diode (IRED) can be used as a light emitter. Photo transistor can be used as a light detector. Principle: Here is one way transistor of electrical signal from LED (IRED) to photo transistor without any electrical connection between the input and output circuitry. The degree foe solation between input and output depends on the kind of material used in the light path and on the distance between the light emitter and signal light detector. If the distance between emitter and detector is greater, then the isolation is better but current transfer ratio of detector to emitter current is lower. Working: The fig shows the symbol of Opto coupler. The coupler may be operated as a switch in which cause both the LED and photo transistor are normally OFF. A pulse of current through the LED (IR...

Well, I got asked if I could put up some more pictures of the finished guitar (and specifically the neck joint), so here's what I've got (apologies for the dust). I thought I had a pic of the wiring too, but I can't seem to find it. Next time I change the strings I'll remove the scratchplate and take some. Enjoy. (EDIT: The wiring pics have now been added below)     And the wiring pics...

Working of UJT 1. If voltage is applied at V BB with emitter open, a voltage gradient is established along the n-type bar. Since the emitter is located nearer to B 2 , more than half of V BB appears between the emitter and B 1 , the voltage V 1 between emitter and B 1 establishes a reverse bias on the pn junction and the emitter current is cutoff. 2. If a positive voltage is applied at the emitter, the pn junction will remain reverse biased so long as the input voltage is less than V 1 . If the input voltage to the emitter exceeds V 1 , the pn junction becomes forward biased. Under these conditions, holes are injected from p-type material in to the n-type bar. These holes are repelled by positive B 2 terminal and they are attracted towards B 1 terminal of the bar. This accumulation of holes in the emitter to B 1 region results in the decrease of resistance in this section of the bar. The result is that internal voltage drop from emitter to B 1 is decreased and hence the emitter curr...

Dynamometer Type Instrument ElectroDynamometer Instrument The electrodynamometer type instrument is a transfer instrument. A transfer instrument is one which is calibrated with a D.C source and used without any modifications for A.C measurements. Such a transfer instruments has same accuracy for A.C and D.C measurements. The electro-dynamometer type instruments are often used in accurate A.C voltmeters and ammeters, not only at the power line frequency but also in the lower audio frequency range with some little modifications, it can be used as a wattmeter for the power measurements. Principle: Electro-dynamometer type instruments are very similar to PMMC type instrument in which the operating field is produced, not by a permanent magnet but by another fixed coil (usually two fixed air cored coils are used). The PMMC instrument cannot be used on A.C currents or voltages. If A.C supply is given to these instruments, an alternating torque will be developed. Due to moment of inertia of th...

Google introduced Android 5.0 Lollipop , the new version of the operating system that implements the Material Design and a breakthrough. Great news comes to Android lovers with the arrival of the latest OS: Android 5.0 Lollipop . Although this was not the only news from Google on this day, no doubt, for fans of the operating system, the presentation of the version that comes after Android KitKat was the most important. These are the top ten news of Android 5.0 Lollipop 1 Material Design The new structure of Android has a flatter design, more colorful and multi-layered, visually respond to your touch screen and is the most drastic change from Android Ice Cream Sandwich. The interface we know Android KitKat reach the next level with a smooth transition animations between applications and elevation for each of the areas of the screen. This allows each section of the screen can offer higher quality and appearance with larger, thanks to the shadows that would be having each of the layers in...

This is a simple Electronic Circuit Project of Power Supply Adjustable 0V-30V DC/2A Circuit. Based on the known LM 723, that drive a transistor Q1 [2N3055]. The regulation of voltage, of expense becomes with potentiometer R1 from 0v-30v DC roughly. Power Supply Adjustable 0V-30V DC/2A Circuit Diagram: In order to we achieve 30 V, will should the transformer of supply TR1, it gives all the current that it asks the load, differently the output voltage it will be found in the levels of 26 V roughly. Essential is the use of a good heatsink for transistor Q1, as well as good quality of potentiometer in the place of R1. Parts List:

Types of Armature Windings The following terms used in connection with armature winding should be kept in mind: (A)     Conductor: The length of a wire lying in a magnetic field is called a conductor. It may be made of one or two or more parallel strands. (B)      Turn: When the two conductors lying in a magnetic field are connected in series, so that emf induced in them help each other or the resultant induced emf becomes double (assuming full pitch coil) of that due to one conductor, it is knows as a turn. (C)      Coil: When one or more turns are connected in series it is termed as a coil. The group of wires or conductors constituting a coil side of a multi-turn coil is wrapped with a tape as a unit. (D)     Coil span or coil Pitch: It is the distance measured in terms of armature slots or armature conductors between two sides of a coil. (E)      Pole pitch: it is defined as the number of con...

Theory or Operation of Inductive Proximity Sensors | How Inductive Proximity Sensor Works?   In this section we will look at Inductive proximity sensors , and how they detect the presence of an object without coming into physical contact with it. Inductive proximity sensors are available in a variety of sizes and configurations to meet varying applications. Specific sensors will be covered in more detailed in the following section. Electromagnetic Coil and Metal Target The sensor incorporates an electromagnetic coil which is used to detect the presence of a conductive metal object. The sensor will ignore the presence of an object if it is not metal.   Inductive proximity sensors are operated using an Eddy Current Killed Oscillator (ECKO) principle. This type of sensor consists of four elements: coil, oscillator, trigger circuit, and an output. The oscillator is an inductive capacitive tuned circuit that creates a radio frequency. The electromagnetic field produced by the os...