presentation ece jec

8/8/2019 Presentation Ece Jec

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Practical

Electronics


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Symbols forSwitches


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Variable Resistors


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Variable Capacitors

Variable Resistors


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Inductorsinductors act to resist changes in current flow while freelypassing steady (dc) current.


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TRANSISTORSWITCH


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RelaysRelays are electrically actuated

switches.

The three basic kinds of relays includemechanical relays, reed relays, and solid-state relays(500 mA to 1 A) (typically 2 to15 A)single-pole double-throw switch


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Relay Driver

If a relay is to be driven by an arbitrary control voltage, this circuit can beused. The npnbipolar transistor acts as a current-flow control valve. With novoltage or input current applied to the transistors base lead, the transistorscollector-to-emitter channel is closed, hence blocking current flow throughthe relays coil. However, if a sufficiently large voltage and input current are

applied to transistors base lead, the transistors collector-to-emitter channelopens, allowing current to flow through the relays coil.


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LDR


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Thermistors (ptc, ntc)

Thermistors are resistors made frommaterials that have large values oftemperature coefcient. Both PTC andNTC types are produced for appli-cations that range from temperature

measurement to transient currentsuppression.


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Resistance Temperature Detection200 to 800 C.


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These LEDs are designed to emit infrared photons that havewavelengthbetween approximately 880 and 940 nm. They are used in conjunctionwith a photosensor (e.g., photodiode, photoresistor, phototransistor)inremote-control circuits (e.g., TV remotes, intrusion alarms). They tendtohave a narrower viewing angle when compared with a visible-lightLEDso that transmitted information can be directed efficiently. Photonoutput

is characterized in terms of output power per specific forwardcurrent.Typical outputs range from around 0.50 mW/20 mA to 8.0 mW/50 mA.Maximum forward voltages at specific forward currents range fromabout1.60 V at 20 mA to 2.0 V at 100 mA.


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v


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PHOTOTRANSISTOR


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PhototransistorsPhototransistors are light-sensitive transistors. A common type ofphototransistorresembles a bipolar transistor with its base lead removed and replaced with a

light-

sensitive surface area. When this surface area is kept dark, the device is off (practically

no current flows through the collector-to-emitter region). However, when thelight-sensitive region is exposed to light, a small base current is generated thatcontrols a much larger collector-to-emitter current. Field-effect phototransistors(photoFETs) are light-sensitive field-effect transistors. Unlike photobipolartransistors,

photoFETs use light to generate a gate voltage that is used to control adrainsourcecurrent. PhotoFETs are extremely sensitive to variations in light but are morefragile (electrically speaking) than bipolar phototransistors.


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Optoisolators


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Half-wave, full-wave, and bridgerectifiers packages


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+15-V Power Supplies


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ADC


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MIC

Preamplifiers


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Mixer Circuits


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Speed Control ofDC Motors

Directional Control ofDC Motors


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REMOTE CONTROL FORHOME APPLIANCES


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IR MUSICTRANSMITTERAND RECEIVER


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Thermistor triggered switch


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DTMF


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SHARP GP2D12 IRDistance Sensor

Range: 10cm-80cm, 0 to 3V

Range: 2cm - 3m (1" to 3.3')

PIRDetector Switch

10ft PRESSURE sensors

SonarDistance Sensor


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APR9600 multi-section soundrecorder/replay ICand experimental board


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