Defination and Classification of Power Amplifier

Definition of power amplifier

A transistor amplifier which raises the power level of the signals that have audio frequency range is known as transistor power amplifier. In general the last stage of multistage amplifier is the power stage. A power amplifier differs from the voltage amplifier. A transistor that is suitable for power amplification is generally called as power transistor.

Classification of Power Amplifier

The power amplifiers can be classified in the following ways.

1. According to the usage of Frequency Signals:

(i) Audio frequency power amplifiers.

(ii) Radio frequency power amplifiers.

(iii) Video frequency power amplifiers.

2. According to the period of Conduction:

(i) Class A Power Amplifiers: The period of conduction is for total 360 ^o(full cycle).

(ii) Class B Power Amplifiers: The period of conduction is for 180^o (half cycle).

(iii) Class AB Power Amplifiers: The period of conduction is greater than 180^obut less than 360^o (in between class A and class B).

(iv) Class C Power Amplifiers: The period of conduction is for less than 180^o.

3. According to the Configuration used:

(i) Single ended amplifier.

(ii) Push pull amplifier.

(iii) Complementary symmetry push pull amplifier.

Comments

Digital Fan Regulator Circuit Diagram

This is the project of Digital Fan Regulator Circuit diagram. The circuit presented here can be used to control the speed of fans using induction motor. The speed control is nonlinear, i.e. in steps. The current step number is displayed on a 7-segment display. Speed can be varied over a wide range because the circuit can alter the voltage applied to the fan motor from 130V to 230V RMS in a maximum of seven steps. The triac used in the final stage is fired at different angles to get different voltage outputs by applying short-dura-tion current pulses at its gate. For this pur-pose a UJT relax-ation oscillator is used that outputs sawtooth waveform. This waveform is coupled to the gate of the triac through an optocoupler (MOC3011) that has a triac driver output stage. Pedestal voltage control is used for varying the firing angle of the triac. The power supply for the relaxation oscillator is derived from the rectified mains via 10-kilo-ohm, 10W series dropping/limit-ing resistor R2.

Home automation with Telegram BOT

The project I’m going to describe today it’s a sort of proof of concept that will demonstrate the possibility to remote control sensors and actuators (for example a couple of relays) via Telegram. Telegram is an instant messaging application, similar to the famous Whatsapp. Last June, the Telegram developers announced that a new set of APIs were available to develop bots. [ ]

OVER LIGHT SENSOR ALARM CIRCUIT

OVER LIGHT DETECTOR Here i am going to Introduce you an Excess light Detector or sensor circuit. The sensing component used in this circuit is LDR (Light Dependent Resistor). LDRs are sensitive, inexpensive and readily available device. They posses good power and voltage handling capacity similar to an ordinary resistor. CIRCUIT DIAGRAM OF OVER LIGHT DETECTOR Components required to wire up this circuit 1. LDR 2. R - 1K 3. SCR 4. Buzzer 5. 5V BATTERY WORKING PRINCIPLE OF OVER LIGHT DETECTOR The LDR is a variable resistor whose resistance decreases with increase in light intensity. When the light falling on an LDR has normal intensity, its Resistance is large enough and the voltage across R is insufficient to trigger the SCR. However, when light falling on LDR is of large intensity, the Resistance of LDR falls and voltage drop across R becames large enough to trigger the SCR. Consequently the buzzer sounds the alarm. It may be noted that if the strong light disappears the buzzer continu

ffd

Search This Blog