Category: Electronics Projects

Universal Crystal Test Circuit Using CA4007

Engineeering Projects
circuit diagram of cristal test circuit

Crystal oscillators may fail to operate due to faulty design or faulty crystals. The circuit shown in figure 1 works well as a crystal tester for a wide variety of crystals and ceramic resonators over the 40-kHz to the 20-MHz range. Circuit Description of Universal Crystal Test Circuit Using CA4007 The oscillator in figure 1 is a Pierce type that operates at the crystal’s parallel resonant frequency and presents about 30 pF capacitance to the crystal. The IC1 (CA4007 A) contains three pairs of complementary MOSFETs with the first (input at…

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Sort Circuit Protected Regulated Power Supply Using 741

Engineeering Projects
short circuit protected regulated power supply

Various Power Supply-based projects are already available on bestengineeringprojects.com like short-proof variable power supply, stabilized power supply with short circuit indicator, Universal digital power supply, variable switching power supply, etc. Now here is a straightforward circuit of short circuit-protected regulated power supply utilizing very few components. Circuit Description of Short Circuit Protected Power Supply The electronics project short circuit protected variable power supply utilizing an op-amp 741, two NPN transistors, and a few passive components. Unregulated or fluctuating voltage is first regulated and smoothened by diode D1 and Zener diode ZD1.…

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Electronic Room Thermometer Using Op-amp 741

Engineeering Projects
electronic room thermometer using op amp 741

These days electronic room thermometer is very popular, though it is expensive. Now here we designed a simple and cheap electronic room thermometer using a temperature sensor and op-amp 741. Circuit Description of Electronic Room Thermometer using Op-amp 741 The heart of the circuit electronic room thermometer is IC1 (LM3911), which is used here as a temperature sensor. The output of this IC is variable according to temperature change. Its output increases at the rate of 10mV/0C rise in temperature. At 00C its output is 2.73V. The output from IC1…

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Light Operated lamp switch using DIAC and TRIAC

Engineeering Projects
light operated on off switch without ic

Various electronic projects using LDR (Light Operated Resistor) are already posted on bestengineeringprojects.com. Now, here is another simple project using LDR called a light-operated lamp switch using DIAC and TRIAC. This circuit utilizes very few components and is so simple that anyone can understand it. Circuit Description of Light Operated Lamp Switch: The circuit of light operated lamp switch utilizes a diac and a triac as semiconductors and LDR as a sensor. LDR is a type of variable resistor that changes its value according to the intensity of light falling…

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Sound Operated On-Off Switch

Engineeering Projects
circuit diagram of electronic clapper

Various remote control-based projects are already posted on bestengineeringprojects.com. Now here is a unique remote control circuit called a sound operated on-off switch and it responds only particular frequency of sound (4.5 kHz) and can control the device from a distance of up to 4.6 meters (15 feet). Most sound-operated switches use clap sound or voice to activate the remote control. Tone frequency generated by clapping or a voice control is not constant and designing a receiver circuit for a particular or ordinary clap or voice is very difficult. To…

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Microphone Amplifier Using Op-amp 741

Engineeering Projects
circuit diagram of microphone amplifier using 741 IC

Various types of basic electronic projects using operational amplifier-based projects are already posted on bestengineeringprojects.com. Now, here is another basic project using an operational amplifier called a microphone amplifier using 741. The circuit microphone amplifier amplifies weak electric signals converted by the microphone to the necessary level. More other circuits using microphones are posted on bestengineeringprojects.com Dynamic Microphone Preamplifier Circuit Listening Bug Circuit using op-amp LM386 DIY Hearing Aid Circuit using 555 Sound Activated 0-30 Minutes Timer Circuit Arduino-Based Automatic Call Answering Machine Sound detector circuit using op-amp 741 Circuit…

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Thermal Touch Switch using op-amp 741

Engineeering Projects
thermal touch switch using op amp 741

Various types of switch circuits like a light operated switch, sound operated switch, etc is already posted on www.bestengineeringprojects.com. Now here is a thermal touch switch that automatic on and off due to the increase and decrease of pre-defined temperature. This type of circuit is useful to operate fans, cooler, etc. Circuit description of thermal touch switch using operational amplifier 741 The circuit comprises an operational amplifier IC (IC1), silicon diode (D1 and D2), and a few passive components to complete the circuit. Diode D1 is used here as a…

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Voltage into Frequency Converter Circuit using 741 IC

Engineeering Projects
voltage into frequency converter circuit

IC 741 is the most used and popular operational amplifier IC, because of its unique feature and low price. Various op-amp 741-based projects are already posted in the operational amplifier-based projects section. Now, here is a simple project using a couple of op-amps 741 IC called voltage into frequency converter. Description of voltage into frequency converter Circuit using 741 IC The circuit of voltage into frequency converter consists of a couple of op-amp 741, a couple of transistors, and a few passive components (resistors). The voltage of 0.5V to 15V…

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Wind Sound Generator Using IC 741

Engineeering Projects
wind sound generator using op-amp 741

Various sound generator projects is already posted in bestengineeringprojects.com in alarm and sound generator section. Now here is one another sound generator circuit using most popular and versatile operational amplifier IC 741. The circuit posted here is of wind sound generator using IC 741 produces wind sound. Circuit Description of Wind Sound Generator Using IC 741 The circuit of wind sound generator comprise operational amplifier 741, two NPN transistors (BC148) and some passive components (resistors and capacitors). Transistors T1 and T2 generate wind sound. A jumper is connected to emitter…

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DC Volt Polarity Indicator Using IC 741

Engineeering Projects
battery polarity indicator

Now, here is another basic electronic project using the most versatile operational amplifier IC 741 “DC Volt Polarity Indicator”. Using the project DC volt polarity indicator one can know the positive and negative polarity of DC volt. This project is very useful for electronics hobbyists to check either battery polarity or polarity at the output of the DC source. The circuit present here is so simple that even electronics beginners can understand how the circuit works. Circuit Description of DC Volt Indicator Using IC 741 The heart of the circuit…

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