Electronic Link

RC and LC clock oscillators

Clock oscillators are circuits which generate square wave or nearlysquare wave signals suitable for digital electronics circuit asclock signal. The most common simple clock oscillator typesare resistor-capacitor (RC) and inductor-capacitor (LC) oscillators.

• CMOS Oscillator - 4 MHz oscillator using 74HC14 and inductor    Rate this link
• CMOS inverter VCO tunes octave to UHF - robust and versatile vco provides a stable output to 300 MHz    Rate this link
• CMOS RC circuits - includes CMOS 555 timer clock oscillator and schmitt-trigger RC oscillator    Rate this link
• Crystal 32.768KHz CMOS Oscillator    Rate this link
• Design and construction of radio frequency oscillators - Some people regard the design of RF Oscillators to be something akin to a "black art".    Rate this link
• Sqaure Wave Oscillator - two gates from a CMOS 4011 NAND chip form a simpel square wave oscillator where the mark space ratio can also be independantly controlled by varying the value of the resistors    Rate this link

Sinewave oscillators

Sine wave oscillators are useful in applications likeaudio signal generation, reference signals for differentapplications and in measurement applications.To vary the frequency of a traditional RC filter based sine-wave oscillator, you should generally use a pair of ganged variable resistors, and you should thoroughly match their characteristics over the entire variation range to satisfy the oscillator's balancing conditions. This restriction leads to problems in the tuning range and high cost, thereby limiting the range of applications.

• 1 kHz Audio Oscillator - This circuit consists of a CMOS square wave oscillator on a frequency of approximately 1 kHz. The RC filter, which has a roll-off frequency of 500 Hz, filters the harmonics, providing a sine-wave output. The oscillator has many uses, sidetone circuits in transmitters and signal injectors for audio tests are just two.    Rate this link
• 68HC11 synthesizes accurate sine wave - you can use a 68HC11 and a 12-bit serial DAC to generate accurate sine waves without using floating-point arithmetic    Rate this link
• 770 Hz Simple CPO - simple sinewave oscillator    Rate this link
• Amplitude-stable oscillator has low distortion, low cost - square wave and sinewave oscillator examples    Rate this link
• Audio signal (sinewave) generators - wien bridge oscillators, twin-t network oscillator and RC phase shift oscillator    Rate this link
• Audio Test Oscillator - Wein Bridge Basic Circuit    Rate this link
• Current-feedback amp yields simple oscillator - handful of components configures a current-feedback op amp as a large-amplitude sine-wave oscillator with independent adjustment of amplitude and frequency    Rate this link
• Digital signals produce pure sine waves    Rate this link
• Gate Deep Oscillator - This is just a variable oscillator based on a bf245 or k 161 fet. By changing the coil it can generate frequency between 0.5 and 300 MHZ. this circuit is useful to test radio circuit such as filter, receiver, transmitter and so on . It can be use for coil tuning thanks to the 100microamo meter built in.    Rate this link
• Gates provide low-cost sine-wave generator - simple device to generate 300 to 4000 Hz test signals    Rate this link
• GIC resonator has inherent amplitude control - This circuit is based on a classic GIC (generalized impedance converter). The sine-wave-oscillator circuit has inherent amplitude stabilization and normally operates from dual power supplies. However, if you connect a few additional resistors, you can operate the circuit with one supply.    Rate this link
• Grounded resistor tunes oscillator - To vary the frequency of any sine-wave oscillator, you usually have to use a pair of ganged variable resistors, and you should thoroughly match their characteristics over the entire variation range to satisfy the oscillator's balancing conditions. This restriction leads to problems in the tuning range and high cost, thereby limiting the range of applications. This sine-wave oscillator is free of the cited disadvantage. You can tune it over a wide frequency range using only one variable resistor. The variable resistor connects to ground, an advantageous fact in many applications. PSpice simulations prove the possibility of tuning the oscillation frequency over three decades (20 Hz to 20 kHz) by varying R1 from 1.2 M. to 1.2 k.    Rate this link
• Grounded resistor tunes oscillator - To vary the frequency of any sine-wave oscillator, you should use a pair of ganged variable resistors, and you should thoroughly match their characteristics over the entire variation range to satisfy the oscillator's balancing conditions. This restriction leads to problems in the tuning range and high cost, thereby limiting the range of applications. This sine-wave oscillator design is free of the cited disadvantage.    Rate this link
• Microcontroller emulates numerically controlled oscillator - Microcontrollers commonly add intelligence or digital functions to products, but they can also provide a variety of analog signals. An 18-pin PIC 16C54 microcontroller, combined with an inexpensive, 8-bit DAC and a simple lowpass filter, can generate sine waves from dc to approximately 50 kHz with a tuning resolution of 24 bits.    Rate this link
• Op-amp oscillators simplify RF designs - a novel circuit that uses a low-cost, high-speed op amp as a crystal-controlled RF sine-wave oscillator    Rate this link
• Programmable oscillator uses digital potentiometers - This Design Idea describes an oscillator in which setting the resistance of two digital potentiometers independently programs the oscillation amplitude and frequency. This design idea uses diode-stabilized Wien-bridge oscillator that generates accurate sine waves from 10 to 200 kHz.    Rate this link
• Simple circuit generates clean sine waves - technique for generating a high-quality sine wave from a square-wave source    Rate this link
• 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.    Rate this link
• Three-Phase Sine-Wave Generator - A circuit generates three-phase sine waves with excellent amplitude and phase symmetry. A variable-frequency, three-phase, sine-wave generator circuit has been designed for use as a source of polyphase excitation in studies of the propagation of traveling waves in plasmas. The circuit internally generates three symmetrical square-wave voltages with precisely 120๏ฟฝ phase difference, each square wave containing only odd harmonics. Three switched-capacitor, six-pole Butterworth low-pass filters (U10, U11, and U12) remove the harmonics but pass the fundamental sine-wave component. The operating-frequency range of the circuit, 10 Hz to 10 kHz, is covered in three decade ranges. A Zener-stabilized voltage-controlled oscillator (VCO) functions as a variable-frequency oscillator and covers just over one decade.    Rate this link
• Voltage controls sine-wave frequency - generates a 50-Hz to 1-kHz sinusoidal waveform that exhibits lower than 60-dB THD    Rate this link

Square wave oscillators

Square wave oscillators are very commonly used as clock sourcesfor digital electronics circuits and similar applications.

• 200-400MHz voltage controlled oscillator - produces clean emitter coupled logic (ECL) type signal between 200MHz and 400MHz, pdf file    Rate this link
• 555 Tone Generator for 8 ohm speaker - used to produce a 1 Khz tone from an 8 ohm speaker    Rate this link
• Adjustable Duty-Cycle Oscillator - This circuit can be built with a single IC, two capacitors, three resistors, two trim-pots, and a diode.    Rate this link
• Amplitude-stable oscillator has low distortion, low cost - square wave and sinewave oscillator examples    Rate this link
• A square wave test signal generator for testing electronic projects - Your first test instrument is propably a simple multivibrator as a signal generator.    Rate this link
• Digital Clock Circuit - This circuit provides a digital square wave that can be viewed directly or used to drive other circuits. It uses the CMOS 4047 Low-Power Monostable/Astable Multivibrator.    Rate this link
• Generator has independent pulse width and frequency adjustments - modified 555 based circuit    Rate this link
• Inverters form three-phase VCO - You sometimes need an inexpensive VCO that can produce evenly spaced three-phase outputs over a wide frequency range. This application uses unbuffered U-type inverters for use in ring oscillator setup which generates relatively squarish somewhat sine-like waveforms. The range of frequencies over which the circuit can operate is more than 1000-to-1.    Rate this link
• Low frequeny oscillator draws only 500 nanoamperes - circuit draws only 0.5 microamps from a 6 volt supply, outpur frequency is 2 Hz but can be tuned up to 300 Hz, based on CD4007UB IC    Rate this link
• Multivibrators, relaxation oscillators and their allies - astable multivibrator, asymetrical multivibrator, complementary multivibrator, series multivibrator, emitter coupled multivibrator and more    Rate this link
• Precision ultra low power oscillator - works much like the classic 555 timer, but draws only about 1.5 microamps from a 3 volt battery, highly stable under varying temperature and supply voltages, pdf file    Rate this link
• Programmable Clock Oscillator - voltage controller oscillator that was designed as a wide range oscillator to generate clock pulses for a stepper motor drive system, frequency could be varied over 1,000,000:1    Rate this link
• Simple Square Wave Oscillator - This simple kit, based on the popular 555 timer IC, generates six preset frequencies - 1Hz, 10Hz, 100Hz, 1KHz, 10KHz and 100KHz. The output is selected by setting a jumper position. It has a wide operating voltage (5-18V) and even provides visual indication (LED) of the output.    Rate this link
• Use printer port as programmable frequency generator - A simple and inexpensive circuit and a simple C program are all you need to turn your PC's printer port into a programmable frequency generator. Using a few low-cost and readily available components, the circuit occupies little space and is easily attachable to the printer port. With this circuit you need only enter the desired frequency, and the PC does the rest. The circuit uses a MAX5130 low-power, programmable, 13-bit DAC, IC1; an OP07 buffer; and an AD537 VFC (voltage-to-frequency converter). The PC controls the DAC using a three-wire serial interface.    Rate this link

Three phase oscillators

 

• Inverters form three-phase VCO - You sometimes need an inexpensive VCO that can produce evenly spaced three-phase outputs over a wide frequency range. This application uses unbuffered U-type inverters for use in ring oscillator setup which generates relatively squarish somewhat sine-like waveforms. The range of frequencies over which the circuit can operate is more than 1000-to-1.    Rate this link
• Three-Phase Sine-Wave Generator - A circuit generates three-phase sine waves with excellent amplitude and phase symmetry. A variable-frequency, three-phase, sine-wave generator circuit has been designed for use as a source of polyphase excitation in studies of the propagation of traveling waves in plasmas. The circuit internally generates three symmetrical square-wave voltages with precisely 120๏ฟฝ phase difference, each square wave containing only odd harmonics. Three switched-capacitor, six-pole Butterworth low-pass filters (U10, U11, and U12) remove the harmonics but pass the fundamental sine-wave component. The operating-frequency range of the circuit, 10 Hz to 10 kHz, is covered in three decade ranges. A Zener-stabilized voltage-controlled oscillator (VCO) functions as a variable-frequency oscillator and covers just over one decade.    Rate this link
• Waveform generator circuits: Three phase oscillator - This circuit is a simple a phase squarewave oscillator, or tristable. It is like a simple bistable oscillator with 3 stages.    Rate this link

Pulse Width Modulation

The Pulse Width Modulator (PWM) is a very useful circuit that outputs a variable duty cycle at a fixed frequency (duty cycle is usually controlled using external control signal, potentiometer or using numericalcontrol). The PWM is very useful in applications like wave generation,motor control and DC power controlling systems. With the aid of a filter, smooth analog waves can be generated usign PWM method.

• Circuits provide 4- to 20-mA PWM control - are useful when you use 4- to 20-mA current-loop signals to control a PWM signal    Rate this link
• Generator features programmable duty cycle - you can program the duty cycle of this simple pulse generator's output    Rate this link
• Pulse Width Modulators - generating PWM waveform is extremely simple with the circuits shown in this page, all circuits are DC control voltage in and PWM out    Rate this link
• PWM circuit uses one op amp - circuit delivers a rectangular signal with duty cycle varying between 0 and 100% in response to an input signal varying from 0 to 5V dc    Rate this link

Oscillators with other waveforms

 

• 20MHz Function Generator - This compact function generator provides sine, square and triangular waveforms up to 20MHz over three ranges using "course" and "fine" frequency adjustment controls. The output level is adjustable from 0 to 2Vp-p. A TTL output is also provided for connection to a frequency counter.    Rate this link
• Audio Oscillator 150 Hz - 150 kHz - This is an ICL8038 based function generator that gives out square wave, saw wave and sine wave outputs.    Rate this link
• AVR Signal Generator - An audio signal generator and sweep generator with wide range, high accuracy and great versatility.    Rate this link
• DDS device produces sawtooth waveform - Ramp or sawtooth waveforms are useful for a broad range of applications, including automatic-test equipment, benchtest equipment, and actuator control.    Rate this link
• Function Generator - Built around a single 8038 waveform generator IC, this circuit produces sine, square or triangle waves from 20Hz to 200kHz in four switched ranges.    Rate this link
• G๏ฟฝn๏ฟฝrateur de fonction 0.1 Hz - 10 Mhz - funacion generator 0.1 Hz - 10 MHz, based on MAX038, text in French    Rate this link
• Low Cost Function Generator - low-cost function generator, based on the Maxim MAX038 high-frequency waveform generator, produces sine, triangle, and square waves from under 1 Hz to over 20 MHz    Rate this link
• Oscillators convert temperature to time - simple arrangement of active-R oscillators can generate an excellent triangular waveform    Rate this link
• Programmable ramp generator has 14-bit linearity - this linear ramp generator uses a DAC, a transistor array, MOSFET switches, and current-steering techniques to achieve 14-bit linearity    Rate this link
• Scheme yields frequency-locked triangle waves - circuit generates frequency-locked triangle waves of constant amplitude, uses readily available TTL and other older-technology parts    Rate this link
• SCR Oscillator - Silicon controlled rectifiers (SCR) can easily oscillate if there is an inductor (a speaker coil in this case) which gives just enough extra voltage to completely switch off the sustain current. In this way a new cycle may start and oscillations set in. It operates over a wide range of supply voltage and components values are not critical at all. Operational frequency in this circuit goes from 100Hz at 11V to 10KHz at 100V.    Rate this link
• Summer linearizes ramp and triangle generators - op-amp adder that sums a reference voltage with the voltage on C1 allows the ramp generator and the triangle-wave generator to charge capacitor linearly    Rate this link
• Triangle and Squarewave Generator - uses common 1458 dual op-amp    Rate this link
• Tri-Waveform Generator - signal generator to test circuits, frequecy range is 20 to 20 kHz, outpus sinewave, triangle wave and square wave    Rate this link
• Versatile Waveform Generator Operates from 0.1Hz to 20MHz - a single-chip source of high-frequency waveforms, the MAX038 can serve both as the core of a moderate-performance waveform generator, and as a card-level waveform source for electronic systems    Rate this link
• Waveform Conversions: Sine to Square and Square to Sine    Rate this link
• Waveform generator circuits - ramp generator, phase oscillator, quadrature sine/cosine oscillator    Rate this link
• Operation explanation of the sawtooth wave oscillator    Rate this link

Phase locked loops

Phase locked loop (PLL) is a system which consists of a voltagecontrolled oscillator, phase comparator and feedback circuit.PLL it's basic form takes in a reference frequency and triesto output the same frequency out (with a known phase shift).With a feedback circuit which contains a frequency dividerit is possible to generate output frequencies which are N timesthe input frequency.

• Inverting latches make simple VCO - simple VCO circuit which is synthesized from inverting latch stages and is tunable to an integer multiple of the input frequency by selecting which output phases feed back to the input multiplexer, suitable to be usable as on-chip clock multiplication in ASICs    Rate this link
• Low-cost circuit biases VCOs for cable and TV - PLLs are useful in a variety of applications, most notably cable and TV tuners    Rate this link
• Selecting passive components for PLLs - PLLs in SERDES circuits typically require external resistors and capacitors. Other PLLs, such as cleanup circuits with high-Q VCXOs, also use external components. Theory and practical experimentation combine to enable you to optimize these components' values, minimizing jitter.    Rate this link
• Software PLL locks VCXO to reference - provides a precisely controlled clock signal using voltage controlled crystal oscillator controlled by microcontroller    Rate this link
• Straightforward techniques cut jitter in PLL-based clock drivers - this article describes jitter and its causes and effects and shows you how to reduce it    Rate this link
• Synchronous oscillator outperforms the PLL - PLL has numerous limitations, including low input-signal sensitivity and contradictory design requirements, synchronous oscillator doesn't suffer from these problems and has many powerful properties    Rate this link
• Technique eases design of high-order PLLs - maintaining stability in high-order PLLs can be a chore unless you know exactly what you are doing    Rate this link
• Understanding VCO Concepts    Rate this link

Microcontrollers used as oscillators

 

• Tone Generation - A general purpose resonator routine is implemented using a PIC17C42. This routine is used to generate multiple tones. A tone signal is normally generated using extensive table lookup schemes.When a multiple tone signal is desired, each tone must have its own lookup table, thus requiring a large amount of storage space, especially when various frequencies are to be generated. This application note implements tone generation using recursive techniques. The algorithm for a resonator is developed and implemented using PIC17C42.    Rate this link

Watchdog circuits for microcontroller and computer systems

The watchdog circuits used with microcontrollers are usuallybuilt in such way that the software running in the microcontrollerperiodically resets the watchdog circuit. If no watchdog circuit"reset" signal is received during a predetermined timeframe, thewatchog circuit will activate it's alarm output (which is usuallyused to reset the microcontroller circuit to start all over).Watchdog circuit then causes an alarm when the software crashed(whn software crashes, it does not anymore give out watchdog reset pulses).

• Universal watchdog fully controls ๏ฟฝ Preset    Rate this link
• Watchdog circuit uses leftover gates - extremely simple watchdog circuti to be used with microcontrollers    Rate this link
• Watchdog timer reboots PCs - watchdog timer reboot the computer if it runs astray, uses a PIC16C84 ๏ฟฝC to provide the watchdog function    Rate this link