The generation of low frequency is generally accomplished with an RC oscillator. The techniques recently developed for frequency synthesis can now be used conveniently with very precise low frequencies required. A low-frequency sine-wave synthesizer well demonstrates accuracy and stability characteristics that can be measured in part per million (even at 0.01 Hz) if it is crystal controlled. Circuit Description of Low Frequency Sine Wave Synthesizer The synthesizer in figure 1 is based on an 8-bit digital-to-analog converter IC AD7523 (IC5) which presents a precise triangle wave to the timing of a…
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Fiber optic telemetry system Using NE555
Complete fiber optic systems are finding widespread use in all types of applications figure 1 provide a very simple fiber optic telemetry system using NE555 that can be used in a variety of telemetry application essentially. The transmitter is an astable oscillator using the popular NE555 (IC1). Circuit Diagram of Fiber optic telemetry system Using NE555 The variable resistance LDR1 contract the rate of the pulse applied to the LED. LDR1 can be any variable resistance transducer such as a strain gauge for pressure sensing, a thermistor for temperature sensing, or…
Read MoreTelephone Converter Circuit
A telephone converter circuit that can be used to power the circuit added to the basic phone is shown in figure 1. This may be more economical/convening than adding a separate power supply from the AC power line or using battery power. It takes the -48V provided by the telephone and efficiently converts it to a well-regulated 5V. Circuit Description of Telephone Converter Circuit A telephone converter circuit does not require the bulk and expensive transformer which is usually used in these designs. It takes the -48V (it can function…
Read MoreUniversal Crystal Test Circuit Using CA4007
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…
Read MoreSort Circuit Protected Regulated Power Supply Using 741
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 D1Â and Zener diode ZD1.…
Read MoreElectronic 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…
Read MoreLight Operated lamp switch using DIAC and TRIAC
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…
Read MoreSound Operated On-Off Switch
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…
Read MoreMicrophone Amplifier Using Op-amp 741
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…
Read MoreThermal 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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