Medium Speed Modem Using SC11004

Engineeering Projects
circuit diagram of medium speed modem

Modems have been often been stand-alone, add-on devices for most data communications equipment. The recent integration of the complex functions a modem performs into a single chip has allowed manufacturers to economically build the modem right into the microcomputer or data terminal equipment. A circuit diagram of such a modem is shown in figure 1. Circuit Description of Medium Speed Modem Using SC11004 All of the signal processing functions needed for a full-duplex, 300/1200-b/s modem, including the FSK and PSK modulators and de-modulators, are integrated on a single chip. It includes…

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Water Level Controller Using NE555

Engineeering Projects
circuit diagram of water level controller

Here is a circuit called Water Level Controller Using 555  which continuously monitors the level in the overhead and ground-level tanks, and switches on the pump whenever the water level in the overhead tanks falls below a predetermined level and switches off the pump whenever it reaches the maximum preset level so that there is no spillage. Further, if the level of water in the lower tank falls below a preset low level, this circuit overrides the commands being sensed from the overhead tank and switches off the pump. This…

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20W Audio Amplifier Using ECN149-ECP149 Pair Transistor

Engineeering Projects
circuit diagram of 20W audio amplifier

High wattage power transistor is matched complementary pair are now readily available. Using such transistor, an economical high power amplifier using a minimum of components and giving a good performance can easily by constructed by an audio enthusiast. Thus, here we had designed a 20W Audio Amplifier Using ECN149-ECP149 Pair Transistor. Circuit Description of 20W Audio Amplifier Using Ecn149-ECP149 Pair Transistor A discrete power amplifier circuit is shown in figure 1 employs the 30W silicon output transistor pair ECN149-ECOP49. This amplifier will deliver 20W into 8Ωwith a 450mV input signal. We…

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Adjustable Ripple-Regulated Power Supply Using 741

Engineeering Projects
circuit diagram of adjustable ripple regulated power supply

Many instruments and equipment, such as function generators, transmitters, trans-receivers, high-quality stereo systems, and radio receivers, require ripple-free power supplies. The most significant feature required in a good quality power supply, besides load and line regulation, is minimum ripple as its output. Circuit Description of Adjustable Ripple-Regulated Power Supply Using 741 In various applications where the ripple is not desired, the circuit adjustable ripple-regulated power supply using 741  shown in figure 1 for adjustable ripple regulated power supply works quite satisfactorily. Here the advantage of op-amps’ enormous gain is utilized along…

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3watt Audio Amplifier Using AC187-AC188 Pair

Engineeering Projects
circuit diagram of 3W audio amplifier

The high wattage power transistor with matched complementary pair is now readily available. Using such a transistor, an economical high power amplifier using a minimum of components and giving a good performance can easily be constructed by an audio enthusiast. Here in this article, we are going to build a 3watt audio amplifier by using complementary pair of transistors. Circuit Diagram of 3watt Audio Amplifier Using AC187-AC188 Pair A discrete 3watt Audio power amplifier circuit is shown in figure 1 employs a complementary output stage featuring the AC 187-AC188 (T3…

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Sequential Timer Circuit Using NE555

Engineeering Projects
circuit diagram of sequential timer using 555

This is a simple sequential timer circuit using NE555 which can be used for psychedelic light, decoration in shops, advertisement boards at night, and parties. The circuit is similar to those published earlier, except for the fact that it incorporates some additional features. Circuit Description Sequential Timer Using NE555 In the circuit sequential timer circuit IC2, IC3 and IC4 are used as monostable multivibrators. The trigger terminals (pins 2) of these ICs are connected in a chain to the previous ICs through an RC differentiator network (0.022 µF capacitor and…

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A Variable Audio Frequency Oscillator Using Op-amp 741

Engineeering Projects
circuit diagram of variable audio frequency oscillator

The frequency of the AF oscillator can be varied over a wide range. It can therefore be used for AF amplifier testing and also as a code practice oscillator. Circuit Description of A Variable Audio Frequency Oscillator Using Op-amp 741 The circuit of variable audio frequency oscillator using op-amp 741 is mainly a Wein Bridge oscillator whose frequency is varied using the gang condenser. While using the IC1 741 (operational amplifier), the use of a split power supply has been avoided by using capacitors C1 and C2, for R4*, a 150-Ω…

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Pulse Width Modulation using 565 IC

Engineeering Projects
circuit diagram of pll generation of pwm and ppm

Pulse Width Modulation (PWM) is a technique to control the average power delivered to the analog devices. With an acquisition of 555 IC amongst most people working with electronic devices, the use of 565 IC is like using two 555 ICs inside a single device. Unlike 555 IC, 565 IC has 14 pins which act as a dual timer. 565 IC is also available with 10 pins.  Nevertheless, they both require the same amount of power supply. PWM using 565 IC is a form of Pulse Time Modulation (PTM), also…

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PWM Generator and Class D Power Amplifier

Engineeering Projects
circuit diagram of pwm generator and class d power amplifier

PWM (pulse-width modulation) forms the basis for a very efficient form of power amplification. The circuit in figure 1 is a so-called class D power amplifier since the actual power amplification is provided to the PWM signal, and since it is of constant amplitude. The transistors used can function between cutoff and saturation. This allows for maximum efficiency (over 90%) and is the reason for the increasing popularity of class D amplifiers as a means of amplifying any analog signal. Circuit Description of PWM Generation Class D Power Amplifier The…

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Frequency Shift Keying (FSK) Generator Using PLL 565

Engineeering Projects
circuit diagram of frequency shift keying (fsk) generator

The generation of frequency shift keying (FSK) can be easily accomplished by switching an additional capacitor into the tank circuit of an oscillator when the transmitter is keyed, in narrowband frequency shift keying (FSK) it is often possible to get the required frequency shift by shunting the capacitance directly across a crystal, especially if frequency multiplier follow the oscillator, as is usually the case. Circuit Description of Frequency Shift Keying (FSK) Generator Using PLL 565 Frequency shift keying (FSK) can also be generated by applying the rectangular wave modulating signal to…

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