Category: Electronics Projects

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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Programmable Timer Circuit

Engineeering Projects
programmable timer circuit

The electronic project “Programmable Timer Circuit” published here can be programmed for more than 250 different time intervals. The programmable timer circuit is not new to electronics hobbyists, various timer circuits have been designed and published so far but the circuit of the programmable timer posted here is the most versatile, inexpensive, and extremely compact timer with an alarm. Description of Programmable Timer Circuit The main part or heart of the programmable timer circuit is a 14-stage binary counter CD4060 (IC1). The clock pulse is generated by connecting capacitor C1,…

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LED Stop Watch Circuit

Engineeering Projects
led stop watch circuit

ICs 555 and 4017 are well-known to electronics hobbyists. Presented here is a very interesting project of an LED stopwatch Circuit using timer 555 and decade counter 4017 ICs. This stopwatch is able to monitor time from one second to 60 minutes. It can be used in sports, laboratories, etc. IC 555 (IC1) is the heart of the circuit. It is used in astable multivibrator mode. The special feature of this mode is that if this pin 4 of IC1  is kept at a high logic, it produces a clock…

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How to Build a Reliable Ni-Cd Battery Charging Circuit: Step-by-Step Guide

Engineeering Projects
Ni-Cd battery charger circuit

Introduction to Ni-Cd Battery Charger Circuits Nickel-cadmium (Ni-Cd) batteries are commonly found in all sorts of household electronics and gadgets. Because these batteries go through frequent use and constant charging and discharging, having a dependable and efficient charger is essential. In this guide, we’ll walk you through a tried-and-true Ni-Cd battery charging circuit designed to safely recharge your batteries while including important protection features to keep everything running smoothly. Features of the Ni-Cd Battery Charger Circuit This Ni-Cd battery charger is designed to charge seven Ni-Cd pencil cells in series…

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