Repository-circuits
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Alarm system designs often require circuitry that can detect whether a phone line is active or broken. With this type of design, the primary difficulty is drawing less than 5 µA from the phone line over a line-voltage range of 24 to 58 V as the standard.... -
Frequency shift keying (FSK) is a popular digital modulation technique for data transmission. Some common applications of FSK modulation include both wired and wireless data transmission as well as infrared remote controls for consumer electronic equipment.....
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Before the advent of broadband communications receivers with synthesized oscillators, high-grade, hamband receivers used crystal oscillators and a variable IF to cover relatively narrow (500-600 kHz) frequency segments. The schematic shows a circuit that....
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This circuit solves the problem of sending data over a cable with no free conductors. The data is OOK (on-off keying) modulated and superimposed on a high-frequency carrier so it can be sent over a low-voltage power supply line.. -
This circuit, a modification of a function-generator circuit, comprises a battery-powered sinewave generator that is continuously adjustable from 100 Hz to 10 kHz.. -
In a number of cases, an inexpensive source of 115-V, 400-Hz power with low distortion is needed for bench tests or mobile applications. This circuit, which uses the Apex Microtechnology PA25 dual power op-amp IC, can be that source... -
This familiar circuit can be implemented with any rail-to-rail-output comparator or the venerable LMC555. The output period is given by 2log(2)RC = 1. 386RC, and the stability is better than ±100 ppm/ °C against temperature and ±100 ppm/V against....
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A common piezoelectric alarm, such as the Murata (Smyrna, GA) PKB5-3A shown, has many valuable attributes. It is compact, lightweight, efficient and reliable. However, the loud, high-pitched sound output can be quite irritating in many applications. The....
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This demodulator is suitable for the quadrature phase-shift keying (QPSK) modulator previously published by the same author, "Novel Low-Cost QPSK Modulator Needs No Adjustments" (electronic design, Sept. 16, 2002, p. 92). Also based on common CMOS logic, it....
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The second-order multipurpose filter described here can perform as a low-pass, bandpass, high-pass, or notch filter at audio frequencies. What makes this filter unique is that all of its characteristics can be varied independently with potentiometers. In.... -
This circuit, which uses a CD4538 retriggerable monostable multivibrator and a CD4011 NAND chip, can sense fluid levels using a variable capacitance ( see the figure ). Such a sensor can be as simple as two adhesive copper foil strips on a saline or....
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In typical push-pull driver applications, the npn-pnp transistor pair is alternately turned on and off using a square-wave signal. A simple driver circuit uses an inverter between the V1 and V2 inputs to toggle the output transistors. However, mismatched....
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Generating sine waves with controlled frequencies over a wide range is difficult when using RC or LC sinusoidal oscillators. However, this performance can be simply created using a wideband digital squarewave oscillator, a counter, and a weighted summing....
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Signals with a know frequency but unknown phase may be detected using an in-phase and a 90 ° shifted reference signal, as frequently used in lock-in amplifiers, synchronous detectors, and frequency-response analyzers. The 90 °-shifted signal is called the....
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In conventional triangular-wave oscillators, hysteresis from positive feedback in the Schmitt trigger determines the voltage levels and amplitude of the triangular waves. With this topology, it`s difficult to independently vary the voltage levels and....
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The versatile circuit shown can be used to realize several different circuit functions ”an astable multivibrator, a monostable multivibrator, a switch debouncer, or a frequency discriminator ( Fig. 1 ). Inverters U1a and U1b are connected as a latch. When....
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Micro or analog? These days it is getting harder to choose. The 555 timer was the benchmark of flexibility. How does it fare today?... -
This article describes a dc-ac inverter circuit that generates the high-voltage ac signal required to drive an electroluminescent (EL) panel. It`s based on the Sipex SP4425 EL lamp-driver IC..
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The FTDI DLP-USB245M is a USB-to FIFO interface module that simplifies the control of multiple steppers by a PC..
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Software-defined radios (SDRs) are used in all areas of communications including ham radio and SWL.. -
Due to their low cost, stepping-motor controllers are often chosen over full-blown, software-driven controllers for a number of applications. However, stepping motors provide rather low torque at high speeds, thus they usually require a starting ramp to....
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Combining armature resistance cancellation (via positive current feedback) with a motion-reversing H-bridge circuit topology offers a new twist in dc servo motor speed control..
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The aim of this circuit is to keep the permanent magnet dc motor running at a constant speed, set externally. To do this, the current through, and the voltage across, the brushes of the motor are monitored..
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Design A Low-Cost 4- To 20-mA Receiver Circuit For Control Loops | analog-to-digital converter (ADC)... -
This design idea explains how to develop a water sensor circuit that can monitor upper and lower water levels.. -
This Idea for Design describes a 12-V dc to 5-V dc (±5%) switched-mode power supply (SMPS). The supply uses a 12-V input from an array of four 3-V dc, 40-mA solar cells connected in series..
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IR`s Wibowa Chou explains the advantages of 4th-generation IGBTs over MOSFETS with a practical solar inverter application...
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A common problem in crystal sinusoidal oscillators is the excitation of unwanted modes of the quartz crystal that degrade the spectral purity of the oscillator. This problem is significant in overtone crystals, particularly if the oscillator is intended for....
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Ambient light is increasingly being used as a source of energy. To help designers of such systems, this circuit accurately measures ambient light intensity over four decades of measurement. The design is highly cost effective and, with the sensor mounted in....
New Circuits
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This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of.... -
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is.... -
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to.... -
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This.... -
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the.... -
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,.... -
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the.... -
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power.... -
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
Popular Circuits
This is a circuit thich I originally included in my book, 22 Tested Transistor Projects,...
A very simple proximity detector electronic project can be designed using this schematic circuit....
Control a relay from an Arduino compatible board. When I try to activate the relay from the...
This accurate one-pulse-per-second clock is made with a few common parts and driven from a 50 or...
1071 touch is the use of audio enhancement technology being introduced high-resolution...
555 Timer enables low-loss single-shot circuit and CMOS4011B NAND gate circuit interface. Standby...
As shown from the switch contacts, proportional to the speed pulse signal Vi, after the...
Direct reading frequency meter by the amplifier, and trigger one-shot circuit and table top...