Vacuum Tubes Valves
Musical & effects
Yagi Uda Antennas
Metal Detector Circuits
Liquid Sensing Circuits
Light Sensing Circuits
Voltage Detector Circuits
Air-Gas Detection Circuits
Human Sensing Circuits
RF & Radiation
Optical Sensing Circuits
Free Energy Circuits
AC to DC & DC to DC
Solar Cell Circuits
Micro Power Circuits
Switching Power Supplies
Light Laser LED
Digital to Analog
Analog to Digital
Data Bus Circuits
Voltage to Pulse
Current to Voltage
Frequency to Voltage
RF Converter Circuits
Sine to Square Wave
Voltage to Current
voltage to frequency
Period to Voltage
Video Wall circuits
TV Video Circuits
Motor Control Circuits
8051 / 8052
PCB CAD Software
Car bike Circuits
555 Timer Circuits
Remote Control Toy
H Bridge Circuit
Interconnection & Timing
Digital Signal Integrity
Digital & Bipolars
Sensors & Detectors
Regulated Power Supply
4 Band Resistor
5 Band resistor
6 Band resistor
Astable Oscillator Circuits
Colpitts Oscillator Circuits
Crystal Oscillator Circuits
Hartley Oscillator Circuits
RF Oscillator Circuits
Sine Wave Oscillator Circuits
Square Wave Oscillator Circuits
Volt Controlled Oscillator Circuits
Wein Bridge Oscillator Circuits
Pierce Oscillator Circuits
1KHz Sine wave Generator
This circuit generates a good 1KHz sinewave adopting the inverted Wien bridge configuration (C1-R3 & C2-R4). It features a variable output, low distortion and low output impedance in order to obtain good overload capability. A small filament bulb ensures a stable long term output amplitude waveform. Useful to test the Precision Audio...
Amplitude-stable oscillator has low distortion, low cost
The multivibrator is a common circuit that consists of an amplifier with both positive and negative feedback (Figure 1a). When the output is positive, the positive input terminal equals ½V+, and the voltage at the negative input terminal changes toward V+. When this voltage exceeds ½V+, the output voltage rapidly changes to V. The positive input...
CMOS hex inverter generates low-distortion sine waves
This Design Idea provides a simple, inexpensive, portable circuit as an alternative to a microcontroller to provide a wide-range source of low-distortion sine waves for audio-circuit design and debugging. Although sine waves from DDS (direct digital synthesis) offer greater stability and fewer harmonics and other spurious-frequency components,...
Crystal Filter Yields Pure Sine Waves
Electronic applications such as distortion and communications measurements require pure (distortionless) sine waves as input test signals. Distortion contained in test signals causes two problems. First, the test signal distortion content must be calibrated so it can be subtracted out of the measurement. Second, processing a distorted test...
Digital signal controls sine generator
The circuit of Figure 1 produces an accurate, variable-frequency sine wave for use as a general-purpose reference signal. It includes an eighth-order elliptic, switched-capacitor lowpass filter, IC3, which uses a 100-kHz square-wave clock signal that microcontroller IC2 generates. (Any other convenient square-wave source is also acceptable.) The...
Programmable oscillator uses digital potentiometers
Digital potentiometers are versatile devices; you can use them in many filtering and waveform-generation applications. This Design Idea describes an oscillator in which setting the resistance of two digital potentiometers independently programs the oscillation amplitude and frequency. Figure 1 shows a typical diode-stabilized Wien-bridge...
synthesizer generates 19-kHz pilot tone for FM baseband signal
This Design Idea presents a low-cost method of generating the basic 19-kHz pilot tone. The 19-kHz pilot tone comprises a baseband signal, and the L+R and LR signals consist of DSBSC (double-sideband-suppressed-carrier) modulation centered at 38 kHz. For a receiver to correctly demodulate the signal, the transmitted pilot tone and LR signal must...
Sine reference is synchronous with ac line
Many applications require a sinusoidal reference voltage synchronized to the ac line voltage. You cannot derive such a reference voltage directly from the ac line because the waveform of the ac line is distorted because of nonlinear loads connected to the line and because the amplitude of the line signal varies. Hence, you cannot use a simple...
Sine wave oscillator II
In this circuit the gain is provided by a FET type op-amp. I have used an LF351, which may be hard to obtain, but the TL071CN or TL081CN may be used and have a faster slewing rate than the LF351. The Maplin order codes are RA67X and RA70M respectively. The wien network is a parallel combination of resistor and capacitor, in series with a serial...
Sine-wave step-up converter uses Class E concept
The circuit requires only one power-switching device, and you can use an analog or a digital signal to drive the switching device. The circuit also requires only a few components: a diode, a switching transistor or a MOSFET, an inductor or a transformer, and a capacitor. Further, the design`s circuit losses are low, and the switching device...
Sine-wave generator outputs precise periods
Rectangular pulse generators, even at high frequencies, are easy to design. However, the design becomes more difficult if you need a signal that contains a precise number of periods with a sinusoidal shape. Although it is easy to produce a good sine wave, the difficulty is producing a signal with a precise number of periods. The signal has to...
18-MHz oscillator with automatic level control
A recent Design Idea described a method for designing simple, high-frequency LC oscillators with few passive components (Reference 1). However, for best results, practical hardware design of a stable oscillator requires more parts and greater complexity. Figure 1 shows a stable, 18-MHz oscillator with automatically leveled output amplitude...
The Wien-bridge oscillator is reborn
To keep the gain constant, the circuit used an incandescent pilot light to provide AGC (automatic gain control). As is true for all incandescent bulbs, the pilot light has nonlinear resistance. When you turn on the circuit, the cold lamp`s resistance is low, resulting in high gain. As the gain increases, the resistance of the warming lamp...
1-Hz to 100-MHz VFC features 160-dB dynamic range
The VFC (voltage-to-frequency-converter) circuit in Figure 1 achieves a wider dynamic range and a higher full-scale output frequency100 MHz with 10% overrange to 110 MHzby a factor of 10 over any commercially available converter.
10Hz - 100KHz Function Generator with AT90S1200
The presented project is a function generator for sinusoidal and square signals production. The output frequency covers the range from 10 Hz to 100 KHz with a step of 2 Hz. The waveform synthesis is based on the D.D.S. technique (Direct Digital Synthesis) and the output frequency is selected through a microcomputer with an embedded thumb...
adjustable bipolar clamp
The easy way to clamp a signal to a given value is to use two zener diodes, connected back-to-back. This method has several disadvantages. The accuracy of the clamping depends on the tolerance of the zener diodes, and the clamping is not adjustable, except by changing diodes. The circuit in Figure 1 is a bipolar clamper with a range of ±1 to...
Controller IC and one-shot form resonant controller
Resonant power supplies are popular because of high efficiency, low noise, and compactness. You can implement a resonant buck or boost converter using a single switch. The regulation of the output in such a converter derives from using a constant on or off time and a variable frequency.
Monostable multivibrator schematic
The schematic for a monostable multivibrator is shown in figure 3-11. Like the astable multivibrator, one transistor conducts and the other cuts off when the circuit is energized.
One-shot circuit is programmable
Figure 1 shows how to digitally program the on-time of a one-shot multivibrator circuit. More and more, the Internet is playing a role in control operations in industrial and R&D endeavors and in household appliances. One-shot circuits are popular choices for the on/off control circuitry.
One-shot provides frequency discrimination
You use a frequency discriminator to compare one signal frequency with another one. A functional feature, retriggering, of a monostable, one-shot 74xx123 multivibrator can yield frequency discrimination. Figure 1 shows a frequency discriminator that determines the relation of input-pulse frequency to a reference frequency. The external...
NE555 Basic Monostable
Here the popular 555 timing IC, is wired as a monostable. The timing period is precise and equivalent to:- 1.1 x R1 x C1 With component values shown this works out at approximately 1.1msec.The output duration is independant of the input trigger pulse, and the output from the 555 is buffered and can directly interface to CMOS or TTL IC`s,...
The Pierce-gate oscillator of Figure 1 is well recognized by most designers, but few understand how to specify the crystal correctly. The crystal used in the topology of Figure 1 can be either a fundamental AT-CUT or BT-CUT. A BT-CUT crystal has poor frequency stability over temperature compared to an AT-CUT. This topology uses a parallel...
This circuit is intended as a reliable replacement to thermally-activated switches used for Christmas tree lamp-flashing. The device formed by Q1, Q2 and related resistors triggers the SCR. Timing is provided by R1, R2 & C1. To change flashing frequency do not modify R1 and R2 values: set C1 value from 100 to 2200µF instead.
Colpitts oscillator for the UHF range
Simplified circuit diagram of the two-stage Colpitts oscillator. In comparison with the classical single-transistor Colpitts oscillator [1,2,5] the two-stage modification includes an extra transistor Q2 and an extra capacitor C3. We note that both transistors, Q1 and Q2 in respect of AC signals are in a common-base configuration.
The use of positive feedback is useful for producing oscillators. The condition for positive feedback is that a portion of the output is combined in phase with the input. For an amplifer with positive feedback the gain is given by the expression below.
Mosquito repelant circuit
The Astable Multivibrator, which is generally used as a signal generator, is once again used here to generate the desired frequencies. It is an excellent example of the fact, how versatile simple basic electronic circuit can be. It seems quite obvious then, that by creating these insects frequencies electronically, we should be able to repel...
n the view of the dramatic drop in the price of crystals used in color TV sets, they now represent an economical way of building an SSB filter. The circuit shown in the diagram is for a filter with a 6 DB band width of roughly 2.2 KHz. By terminating the input and output with a 1 K Ohms resistor in parallel with an 18 pf trimming capacitor,...
0 to 9 asynchronous decade counter 7490 display
The circuit is based on asynchronous decade counter 7490(IC2), a 7 segment display (D1), and a seven segment decoder/driver IC 7446 (IC1).The seven segment display consists of 7 LEDs labelled a through g. By forward biasing different LEDs, we can display the digits 0 through 9.
Astable Multivibrator with 2 Transistors
This circuit is basically simple and easy to build, it uses two transistors as active components and a few passive components like resistors, capacitors and two LEDs. The circuit makes use of the MPS2222 transistor. You can use any NPN type transistor as the basis of your circuit provided that, the transistors Emitter-Base Voltage is less...
Simple 555 Timer Monostable Circuit
The two circuits below illustrate using the 555 timer to close a relay for a predetermined amount of time by pressing a momentary N/O push button. The circuit on the left can be used for long time periods where the push button can be pressed and released before the end of the timing period. For shorter periods, a capacitor can be used to isolate...
Dual Precision Monostable Logic circuit (CD4538BC)
The logic diagram of the CD4538BC Dual Precision Monostable is shown in the following schematic diagram. This IC such a dual, precision monostable multivibrator with independent trigger and controls, according to the datasheet. This CD4538BC IC features wide supply voltage range, wide pulse-width range, low standby current, high noise immunity...
RF oscillator circuit (2N3904)
This basic RF oscillator circuit is easy to build and the components are not critical. Most of them can be found in your junk parts box. The L1 antenna col can be made by close winding 8 to 10 turns of 22 gauge insulted hookup wire around 1/4 inch form such as a pencil.
Ultrasonic distance finder circuit
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 measured. There are three main categories of distance measurement methods in use: a) By...
Simple Metal detector circuit with CD4030
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 find something potentially valuable, hidden a few centimeters below the soil. So many...
Fully automatic watering circuit for flower pots
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 circuit comes as a solution to this problem. Depending on humidity of the pot at...
Simple deep searching metal detector circuit
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 circuit of this metal detector, it is possible to detect a metal coin in depth of 90 to...
Sub-Harmonic Bass Converter for Electric Guitars
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, such as filtering or distortion. Instead, a frequency division system produces outputs...
Echo Depth Sounding Sonar for Boats
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 calibration of the rope. This arrangement still exists in some yachts. The big...
100W HiFi Audio Amplifier Circuit
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 supply must be symmetrical so that no electrolytic capacitors are needed at the outlet....
Plant-Pot Water Level Indicator Circuit
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. The circuit of the device is shown in Figure 2. The water detection is made from the bottom...
Analogue Sound Preasure dB-Meter Circuit
The best human ear can capture sounds from 20Hz to 20KHz. These limits are known to be the broadest that can exist. Normally the normal limits range from 100Hz to about 13KHz and depend on the age and health of the individual. We for our measurements and to have a good accuracy we will get the limits of 20Hz to 20KHz. A sound to be heard does...
Digital Signal Integrity
Interconnection and Timing of Digital Circuits
CMOS Circuits Tutorial