Simple Preamplifier Circuit using Single Transistor

Engineeering Projects
circuit diagram of simple preamplifier using transistor

The project posted here is of simple preamplifier circuit and is the simplest possible. This circuit provides a voltage gain of about 3 to 30 and is dependent upon source and load impedance. The simple preamplifier circuit has low input impedance. Description of Simple Preamplifier Circuit The circuit of the simple preamplifier is designed using a single low power amplifier transistor and is configured in common emitter mode. The input signal is given to the base of transistor T1 through capacitor C1. Capacitor C1 is a coupling capacitor to couple…

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Listening Bug Using op-amp 741

Engineeering Projects
listening bug thumbnail

Here is a simple project called listening bug circuit using 741 using the most popular op-amp IC 741. This circuit can be used for spying because by using this circuit we can hear any conversation held in any other room or we can say using this circuit one can hear the conversation held in another room. This circuit can also be used for baby monitoring. Also, check our Listening Bug Circuit using op-amp LM386. Description of Listening Bug Circuit Using 741 The circuit of the listening bug shown in figure…

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Metal Detector Circuit

Engineeering Projects
author prototype of simple metal detector

Metal detector is a device which is used to detect metallic object like metal coins, iron ore, aluminum or silver and gold etc. Here, we teach you how to make a metal detector circuit with which you can hunt hidden treasure. This simple metal detector circuit can also be used to detect buried cable or concealed wiring. You can also checkout metal detector using arduino. Description of Metal Detector Circuit This metal detector circuit is designed using three NPN transistors, IF transformer, search coil and few passive component. The metal…

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Toy Siren Circuit Using CD7400

Engineeering Projects
circuit diagram of toy siren using cd4700

Various sound generating project is posted in Alarm and Sound Generation Section. Now here is very simple an easy to construct electronic project called Toy Siren using CD7400 (IC1). Circuit Description of Toy Siren Circuit Using CD7400 The heart of the project toy siren circuit is quad-2-input NAND gate IC CD7400 (IC1). IC1 (CD7400) is a cheap easily available IC and it consist four NAND gate. Two NAND gate out of four is configured as low frequency oscillator and another two NAND gate as high frequency oscillator. When output of…

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Electronic Pendulum Using NE555

Engineeering Projects
circuit diagram of electronic pendulum using 555

Here is a simple, cheap and vary interesting electronic pendulum. The project electronic pendulum using NE555 can be used in various other gadgets i.e. it can be used in digital clock for pendulum view. Circuit Description of Electronic Pendulum Using NE555: The circuit of electronic pendulum comprises a timer IC NE555 (IC1), CD7400 (IC2), 4-bit up-down counter IC CD74193 (IC3) and a BCD to decimal decoder IC 7442 (IC4). Timer IC NE555 (IC1) is configures in astable multivibrator mode and generate square wave. The frequency of square wave generating from…

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20W Audio Amplifier Using TDA2020

Engineeering Projects
circuit diagram of 20W audio amplifier using tda2020

20W Audio Amplifier Using TDA2020 Here is one another circuit in the series of audio power amplifier. We had already posted audio amplifier using transistor (3Watt, 10Watt and 20Watt) and using IC (7Watt and 20Watt). We used here IC TDA2020 for designing audio amplifier circuit. TDA2020 (IC1) can deliver a maximum of 20Watt into a 4Ω loads. Like the TBA810, the TDA2020 also incorporated thermal shutdown, and output short-circuit protection. The input impedance of the circuit 20Watt audio amplifier using TDA2020 is determined by resistor R1 and sensitivity is determined…

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7W audio amplifier using TBA810

Engineeering Projects
circuit diagram of 7W audio amplifier using tba810

Here is another circuit in the series of audio power amplifiers. Previously we had already posted 3W and 20W audio amplifiers using transistors. Now we use an integrated circuit instead of transistors for designing audio amplifier circuits. By using IC TBA810 one can get a power output of 7W. The audio power amplifier featuring the TBA810 integrated circuit is shown in figure 1. This IC incorporated build-in-terminal shutdown, which automatically reduces the output in the event of sustained overloads or if the heat sinking arrangement is inadequate. We use a…

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Advance Mini UPS Circuit

Engineeering Projects
author prototype for mini ups

Mobile phones and small electronic gadgets are powered by AC mains using an AC adapter. In the event of mains failure, a low-capacity UPS will do the job satisfactorily. Here we design a simple, efficient, economical, and easy-to-construct UPS for mobile phone or telephone sets. The project advanced mini-UPS circuit can also be used for high power by changing a transformer with a high current rating so this circuit can be used as power backup for laptops also. We have already posted 350VA Offline UPS Circuit. Block Diagram of Advance…

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Beeper Circuit using Timer IC 555

Engineeering Projects
circuit diagram of beeper using timer ic 555

Here is a beeper circuit employing two timer ICs NE555 (IC1 and IC2). The beeper circuit using timer IC NE555 can be used in various circuits that require an alarm or a ‘beeping’ signal. Description of Beeper Circuit Using Timer IC NE555 Timer IC1 is  used here  in astable mode in such a way that square-wave output at about 1 Hz is obtained. IC2 is also configure  in astable mode, but it gives an output with about 1 kHz frequency. The output if IC1 (pin 3) is connected to ‘Reset’…

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Advance Emergency Light Circuit

Engineeering Projects
block diagram of emergency light

Many types of emergency light circuits are already available in the web world. Now, here is a unique circuit that glows a fluorescent tube at a voltage as low as 80 volts. This unique circuit Advance Emergency Light Circuit operates at a 12V battery and also charges the battery up to 12V, 15AH at a constant rate. Block Diagram of Advance Emergency Light Circuit The block diagram of the advanced emergency light circuit with charger unit is shown in figure 1. It consists of a power supply for emergency light,…

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