Category: Electronics Projects

Door Bell Circuit

Engineeering Projects
circuit diagram of door bell

This project describes the constructional and working details of a door bell circuit. The door bell circuit presented here is of 2-notes (modulated sound) type and delivers about 4-watt Musial power at 12 volt. While using it as a door bell circuit, 6V DC supply is enough, which can be derived either from dry battery cells or a battery eliminator. The door bell circuit is flexible enough to work off right from 6V to 18V supply, without change of any component in the circuitry. However, it is important to use…

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Temperature Deviation Indicator Using OP-AMP 741

Engineeering Projects
circuit diagram of temperature deviation indiator

For laboratory work, an accurate temperature deviation indicator is more effective than a sophisticated thermometer. The electronic device temperature deviation indicator using 741 can register a difference of 0.20C between the thermal sources and display it with the appropriate direction of variation. It can be used as a heater coil controller to maintain the equilibrium level. Circuit Description of Temperature Deviation Indicator using op-amp 741 The circuit of temperature deviation indicator using op-amp 741 is simple and self-explanatory. Two silicon diodes (D3 and D4) complete a bridge network and act…

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Low Pass Filter Circuit | Low Pass Filter Design

Engineeering Projects
circuit diagram of low pass filter using lm387

An electric filter or simply a filter is an electric network that passes or allows without loss, the transmission of electric signal within a certain frequency range but stops or disallows transmission of electric signal outside this frequency range. The low-pass filter circuit is also known as a scratch filter and is used to roll off excessive high-frequency noise from worn-out records and tapes. Or we can also define low pass filter as, it passes all frequencies up to a specified frequency, called the cutoff frequencies fc, and reject all…

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High Pass Filter Circuit | Rumble Filter

Engineeering Projects
circuit diagram of high pass filter using lm741

An electric filter or simply a filter is an electric network that passes or allows without loss, the transmission of electric signal within a certain frequency range but stops or disallows transmission of electric signal outside this frequency range. The three most-popular filters found in audio equipment are the High Pass Filter (rumble filter), Low pass filter (scratch filter), and speech filters. The rumble filter is a high-pass filter, used to suppress the low-frequency rumbling sound associated with old and worn-out turntable and tape deck mechanisms. Here we explain to…

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Bass Treble Circuit

Engineeering Projects
circuit diagram of bass treble unit

Among different types of amplifiers available in today’s technical world, sometimes we get stuck with the audio frequency amplifiers which provide flat frequency low-frequency notes should be amplified more than the high-frequency note stable). The provision of bass treble is accordingly made to gratify the users and to compensate for the effect of noise that comes along with the signal. The bass treble combination is given a single name; tone control. Circuit Description of Bass Treble Circuit Talking about the bass treble circuit, it is comparatively much simpler and gainful.…

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Water Level Indicator Circuit using 7-Segment

Engineeering Projects
circuit diagram of water level indicator

Normally we have seen on different websites, the overall circuit of the water level indicator uses a bar graph or a seven-segment display to indicate the water level. This type of representation using LEDs or digits for water level makes the observer which includes a large number of normal people, difficult to understand. A consequence of using those methods makes the whole effort inadequate. The circuit presented below surmounts this flaw and displays the water level using a seven-segment display, but there is a difference. The water level indicator circuit…

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Electronic Code Lock Circuit

Engineeering Projects
circuit diagram of electronic code lock

Using codes for security has been a popular trend recently. A similar type of electronic project is presented right below called the electronic code lock circuit which ensures the use of four digits in the code locking process and these codes are keyed in remotely. The code can be unlocked easily by pressing the right keys and if someone presses the wrong keys, it resets the lock automatically. The complete phenomenon of the electronic code lock systems has been described briefly in the further paragraph. Description and Working of Electronic…

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Add on Device For Telephone

Engineeering Projects
circuit diagram of add on unit for telephone

This electronic project, Add on Device For Telephone has multiple applications when used with the telephone lines. Since it is added parallel on the telephone system, it is called add-on device. The circuit add on device for telephone supports three modes of operation: on-hook, off hook, and ringing modes. It also provides the audio-visual indication of these operations. Using the relay, add on device circuit can connect the telephone to a CID (caller identification device). It can also be used to indicate tapping or misuse of telephone lines with the…

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Tone Control Circuit (Active and passive)

Engineeering Projects
circuit diagram of active tone control using single transistor

Among the most popular control circuit found in an audio system is tone control. The tone control is used to modify the tonal characteristic of the signal chain i.e. it enables the listener to alter the tonal quality of the sound being reproduced. The effect of tone control has on the frequency response of the equipment and their purpose is to help remedy shortcomings in the source program material, the receiver or transducer, or in the loudspeaker and the listening room combination. These are either of the passive types, of…

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Phone Broadcaster Circuit

Engineeering Projects
circuit diagram of phone broadcaster

An interesting circuit design that is also used as a wireless telephone amplifier, is demonstrated below which has been proven very useful in prying on a telephone conversation and therefore is termed a phone broadcaster circuit. The more amazing or we can say a comforting fact about the phone broadcaster circuit design is that it draws the power essential to operate the circuit directly from the active telephone lines. Therefore, it avoids additional expenses in external battery and prevents the circuit from the extra bulkiness of other power supplies. Circuit…

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