16-10-2012, 08:44 PM
I need abstract of led activated by voice.
16-10-2012, 08:44 PM
I need abstract of led activated by voice.
20-10-2012, 12:44 PM
Led Motor Activated by Voice
Led Motor Activated.doc (Size: 355.5 KB / Downloads: 26) ABSTRACT A transistor is a solid-state, semiconductor device with three electrical connections (emitter, base, collector). A small current flowing between base and emitter has the ability to control a much larger current flowing between the collector and emitter. Transistors can be manufactured in two distinct configurations: PNP or NPN. The N's and P's refer to the kind of impurity introduced into the crystal structure of the various regions of the transistor. This determines which way the currents flow through the transistor. The circuit symbol for a transistor reveals its configuration by the direction of an arrow placed on the emitter lead and distinguishes the emitter from the collector as shown in Figure 1. 555 TIMERS Introduction The 555 timer is an integrated circuit (chip) implementing a variety of timer and multivibrator applications. It was produced by Signetics Corporation in early 1970. The original name was the SE555/NE555 and was called "The IC Time Machine". The 555 gets its name from the three 5-KΩ resistors used in typical early implementations. It is widely used because of its ease to use, low price and reliability. It is one of the most popular and versatile integrated circuits which can be used to build lots of different circuits. It includes 23 transistors, 2 diodes and 16 resistors on a silicon chip installed in an 8-pin mini dual-in-line package (DIP-8) The 555 Timer is a monolithic timing circuit that can produce accurate and highly stable time delays or oscillations. The timer basically operates in one of the two modes—monostable (one-shot) multivibrator or as an astable (free-running) multivibrator. In the monostable mode, it can produce accurate time delays from microseconds to hours. In the astable mode, it can produce rectangular waves with a variable duty cycle. Frequently, the 555 is used in astable mode to generate a continuous series of pulses, but you can also use the 555 to make a one-shot or monostable circuit. The 555 can source or sink 200 mA of output current, and is capable of driving wide range of output devices. The output can drive TTL (Transistor-Transistor Logic) and has a temperature stability of 50 parts per million (ppm) per degree Celsius change in temperature, or equivalently 0.005 %/°C. |
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