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cell phone detector circuit design

Cell phone detector  Before looking at the circuitry of a the detector, we need to have some pre-knowledge and its constituents. A cell phone detector is used to detect signals from an activated cell phone at a defined distance. In our case, the distance can range up to 1.5 meters. A basic digital cell phone contains just a few individual parts: — A circuit board containing the brain of the phone — An antenna — A Liquid Crystal Display (LCD) screen — A keyboard — A microphone — A speaker — A battery The circuit board is the heart of the system and contains several chips. The analog-to-digital and digital-to-analog conversion chips  that translate the outgoing audio signal from analog to digital and the incoming signal from digital back to analog. The digital signal processor (DSP) is a highly customized processor designed to perform signal-manipulation calculations at high speed. The microprocessor handles all the functions for the keyboard and dis...

Why are gravel/stones used in substations or switch yards

Reasons why stones are used in substations or switch yards The stones used in substations vary from 2-2.5 inch. There are numerous reason of using gravel or stones in substations. These are: In case of fire outbreak and oil leakage in transformer, the stones prevent the oil spills from a rampant fire outbreak since the oil sinks beneath easily. They are also used to easily identify oil leakages in transformer. Stones reduce the step and touch potential of operators on the switch yard since they have an increase resistance thereby increasing soil resistance. So, stones reduce the possibility of an electric shock of the operators. Prevent a pool of water during rainy periods since water sinks beneath the stones. Keeps the ground wet by maintaining the moisture beneath, and provides minimum moisture above the ground ( on gravel). Working condition is improved by these stones. Stones reduce the growth of plants in switch yards Protect from wildlife and other animals lik...

contactor numbering, thermal relay, timer normally open and close contacts

Switch gears and their contact numbering We shall be looking at the various Switch gears and the numbering of their contacts. Switch gears such as contactors, timers and relay. As an engineer you have to know all the contacts of these switch gears which will permit you to carry out installations easily. These switch gears here include: Contactors Thermal relays Timers. etc. Here are the various switch gears and their contacts number. Normally open contacts (NO) 1) Contactor Contactor -  13 & 14 Contactor  - 33 & 34 Contactor -  63 & 64 Contactor's main contact which are normally open are numbered 1-2 or L1-T1 respectively 3-4 or L2-T2 5-6 or L3-T3 2) Thermal relay (Overload)  -  97 & 98 3) Timer   -  15 & 18 Normally closed contacts ( NC ) 1) contactor Contactor  -  21 & 22 Contactors  -  31 & 32 Contactors  -  61 & 62 2) Thermal relay (Ove...

Why transformers are rated in KVA

Reasons why transformers are rated in KVA Transformer It is important to know what is a transformer. A transformer is a static device which converts electrical energy from one voltage level to another at the same frequency. Transformers are rated in KVA not in KVAR nor in KW because of the following reasons: KVA=Kilo Volt X Ampere meanwhile KW=Kilo Volt X Ampere X Power factor since   transformers are rated based on the maximum amount of power they can transfer, we see that the apparent power in transformers ( total power= active power+reactive power) is independent of the power factor.  A transformer is not a load but only transfers energy from the primary to the secondary at same power and the iron loss and cu loss in transformers are independent of the power factor. The power factor is only associated with loads which may be: Inductive- lagging pf Capacitive-leading pf Resistive (unity power factor) Examples are motors 🔙HOME

Download AutoCAD with crack | keygen

Autodesk AutoCAD 2017 (x64) + Keygen Autodesk is one the best software used by professionals, engineers, architects and students to creat wonderful designs you can ever imagine of. Domains  - civil engineering -mechanical engineering - electrical engineering DOWNLOAD Name: Autodesk AutoCAD Version: (64bit) 2017 Home: www.autodesk.com Interface: english OS: Windows 7even / 8 / 10