EC ELECTRIC CIRCUITS AND ELECTRON DEVICES the equivalent circuit of UJT and explain its operation. Write short notes on light activated SCR. 2nd Semester CSE Notes: 1. Basic civil & Mechanical Notes and Question answers – View. 5. Electron Devices & Electric circuits (EC) – Unit 1 – View /. PH Engineering Physics 2 Anna University Notes: PH Engineering notes (EM notes – ME Notes) – DOWNLOAD EC

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Selectivity Selectivity is defined as the ratio of bandwidth to the resonant frequency of resonant circuit. It is used as a variable reactance capacitance.

The light thus produced is emitted from the p-n junction of the diode. This ability of the SCR to remain conducting, even when the gate signal is removed, is known as latching. Algebraically add mesh currents to find current in components sharing multiple mesh currents. It has a window and lens which focuses light on the gate junction area. The amount of light output is directly proportional to the forward current.

Second Semester Anna University lecturer notes – Site Title

Now we plot a graph with anode current and anode cathode voltage. Adjust the gate current to zero value by keeping the switch open. Current conduction in the external circuit is by electrons. Where two mesh currents intersect through a component, express the current as the algebraic sum of those two mesh currents.

Explain the following terms: Select a reference node E0 Assign unknown voltages E1 E Its intensity can be controlled easily. The right hand side of the equations is the current source connected nktes the respective nodes. At these frequencies the power from the source is half of the power delivered at the resonant frequency. The time taken for the circuit to change from one steady state to another steady state is called the transient time.


Used for entering information into optical computer memories Used for solid video displays. The mobile charges have been depleted in this region.

Its cost is very low. Transistor Biasing Applying external voltage to a transistor is called biasing. Hence tunneling takes place from p to n-side.


If any solution is negative, then the assumed current direction is wrong! Write short notes on light activated SCR. At the junction, there is a tendency for the free N-type of diffuse over to the P-side and holes from the P-side noyes the N-side.

Such curves are known as Static characteristic curves. Symbol Anode Cathode V-I Characteristics of Zener diode The operation of zener diode is same as that of ordinary p-n diode order forward biased condition, whereas under reverse biased condition breakdown of the junction occurs. Now, there will be some empty state in valence band of p-side quite opposite to the empty conduction band.

To reduce the holding current, it can be turned OFF. Increase the applied voltage across the SCR in small suitable steps at each step.

The movement of the hole-electron pairs in a properly connected circuit results in current flows.

Second Semester Anna University lecturer notes

Solve for unknown mesh currents simultaneous equations. It also exhibits a negative resistance characteristic which allows it to be used as an oscillator. Response time of LED is very fast in the order of 10 9 seconds. It has two main terminals namely Main terminal 1 and Main terminal 2.


The second method wc2151 anode current interruption. At resonance series RLC circuit acts as a voltage amplifier.

It has thermal stability. At anti resonance the parallel resonant circuit acts as current amplifier.

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The two leads are connected to p-region of silicon separated by an n-region. Characteristics of Varactor diode The diode conducts normally in the forward direction. It differs from ordinary PN diode in the sense that it sc2151 three terminals namely Emitter, Base1 and Base 2. A lens focuses the energy on the base-collector junction. However, it has ability to control large ac power with a small signal. Because, it produces a very low ecc2151.

Adjust the gate current to any suitable value. Inverse Laplace transforms permits going back in the reverse direction i. The light energy fall on the junction through lens, when, the PN photodiode junction is reverse bias.

The sharp increase in current under breakdown condition is due to the following two mechanisms. Series resonance circuit is always driven by a voltage source with very small internal resistance to maintain high selectivity of the circuit.

SCR characteristics It is the relationship between the anode —cathode voltage and anode current at different gate current. Describe the operation of Zener diode and explain its characteristics. Valence band Classification of semiconductors 1.