Category: Electronics Projects

Double tune Car Reverse Horn

Engineeering Projects
double tone car reversal horn

Several circuits of musical car horn have been published in BEP but “Double tune car reverse horn” differs from them. Projects like this helps you to get more used to various electronic devices. The circuit that produces the double tune car reverse horn generates two types of sounds: one is a pleasant ‘ding-dong’ bell sound and the other one is a sweet chirping sound of a bird.  Here, the IC HT82D (IC1) is used as the sound generator whose operating voltage range is 2 to 5 volts. It has 10…

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Priority Lamp Circuit

Engineeering Projects
priority lamp system

The circuit described here is a Priority Lamp Circuit which gives priority in switching. Switches SW1 to SW4 is a push-to-off type or push-button type, as desired. Normally, pushing off any switch will turn ‘on’ the corresponding relay, i.e. pushing of SW1 enables the NPN transistor T1, and hence relay RL1 operates. The logic section of is designed to get a controlled high output. The pressing of one switch disables the operation of all switches and results in priority in switching. In normal cases, all switches are closed and all relays…

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Programmable Digital Timer Circuit

Engineeering Projects
programmable digital timer circuit

The project “programmable digital timer circuit” presented here can be used for setting time intervals in the range of 1 to 99 minutes. The circuit of a programmable digital timer does not use large resistors or capacitors to obtain the timing interval. Instead, it uses the 50 Hz mains frequency as a reference. The main frequency is fairly accurate for this application. The main frequency is shaped up by Schmitt-trigger gate N1 to obtain a square wave. This 50 Hz square wave is divided by IC1, IC2, IC3, and IC4.…

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Self Switching Off Power Supply Circuit

Engineeering Projects
self switching off power supply circuit

This Self Switching Off Power Supply Circuit switches itself off when no current is drawn by the load. When a load current flows, the potential difference across diode D6 is sufficient to cause diode D7 = and transistor T2 to conduct. Transistor T1 is then switched on and the relay is energized. If you are new to relay drive circuits then you can watch this making video on How to make relay switching circuits. When the load current ceases, T2 switches off. The base current of T1 then charges capacitor…

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Simple Power Supply Resumption Alarm

Engineeering Projects
simple power resumption alarm

Once again the most popular timer IC NE555 proved that its applications are limited only to the user’s ingenuity. The circuit of the simple power resumption alarm shown here is straightforward, where IC1 is wired in a special kind of mode. Circuit Description of Simple Power Supply Resumption Alarm When the power supply resumes, pin 2 of IC1 is grounded through C1 and pin 3 goes high. This makes reset pin 4 go high for about 10 seconds. When the capacitor C1 charges to two-thirds of the supply voltage, the output…

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Staircase Light Switch Circuit

Engineeering Projects
staircase light switch

This project “Staircase Light  Switch Circuit” may be used where it is necessary to control a single light or device by switches situated at different places. The control of a staircase light switch circuit is one of the applications of a light switch circuit. Staircase Light switch circuit can also be used to control an outdoor light using switches situated both inside and outside of the house. Any number of switches may be connected to the light switch circuit. As the switches are wired in parallel, the wiring can be…

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Rain Sound Generator Circuit

Engineeering Projects
rain sound generator circuit

The project described here is of “Rain Sound Generator Circuit” which is simple and uses ordinary components. It comprises two oscillators: one is a variable low-frequency oscillator that uses UJT 2N2646 (T1) and the other one uses timer IC NE555. A single UJT (Unijunction Transistor) can be oscillated without using a tank coil. The electrical characteristics of UJT are quite different from ordinary bipolar transistors.  The second oscillator using timer IC NE555, IC1 is in astable mode. Here, T1 acts as the noise generator for the circuit. The sound produced…

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Versatile Auto Cut -Off Unit

Engineeering Projects
auto cut off circuit

A versatile auto cut-off facility is necessary for all the mains operated equipment and voltage stabilizers (automatic as well as manual) to switch them off when the voltage shoots above or falls below a certain safe level. The cut-off facility available in most commercial stabilizers is so abrupt that they switch off the moment the voltage goes beyond a predetermined window (normally, 180V to 250V) and switch on immediately after the voltage fall within the calibrated range. Introduction to Versatile Auto Cut-Off Unit Power interruptions are quite frequent at times…

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Advanced Quiz Display with Seven Segment Indication

Engineeering Projects
quiz display circuit using 7-segment display

Quiz contests are become progressively more popular and the “buzzer” round are now an integral part of such contests. As we all know that in this round each team is provided with push-button switch and questions are addressed to each team. The team that presses the button first is allowed to answer the question. The circuit which perform this task or which can be used for this purpose is published here “Advanced Quiz Display with Seven Segment Display”. It can accommodate up to 8 teams through switch SW1 to SW8.…

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Frequency Multiplier Circuit

Engineeering Projects
programmable frequency multiplier circuit

Here is a  Frequency Multiplier circuit using PLL565.  Phase lock loop (PLL) has many diverse applications, among its applications PLL exhibits tremendous flexibility in frequency multiplication.  The IC 565 (IC1) can be used over the frequency range of 0.001 Hz to 500 kHz, and an operating voltage range of 6V to 12V. The frequency multiplier circuit  has a highly stable center frequency, selected by an external resistor (R1) and Capacitor (C1), which is given by The capture range of the feedback control system of the frequency multiplier circuit is decided…

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