Volt Controlled Oscillator Circuits
Volt Controlled Oscillator Circuits
The 566 can be wired as a positive or negative ramp generator. In the positive ramp generator, the external transistor driven by the Pin 3 output rapidly discharges Cl at the end of the charging period so that charging can resume instantaneously. The pnp transistor of the negative ramp generator likewise rapidly charges the timing capacitor Cl...
Simple voltage controlled oscillator
With the component values shown, the oscillator has a frequency of 8 kHz. When an input signal is applied to the base of Ql the current flowing through Ql is varied, thus varying the time required to charge Cl. Due to the phase inversion in Ql the direction of output frequency change is 180 degrees out of phase with the input signal
A voltage-variable capacitance tuning diode is placed in series with the crystal feedback path. Changing the voltage on VR varies the luning diode capacitance and tunes the oscillator. The 510-KO resistor, R1, establishes a reference voltage for VR -ground is used in this example. A 100-KO resistor, R2, isolates the tuning voltage from the...
This TMOS VCO operates in push-pull to produce 4 Wot 70 MHz. It consists of two MFE930 TMOS devices in a balanced VCO that generally provide better linearity than the single-ended types. Varactors are not used because the design takes advantage of the large change in Miller capacitance, G?ss, that is available in TMOS gate structures.
You can transform a 7415124 multivibrator into a wideband VCO by replacing it conventional fixed capacitor with a variable-capacitance diode. The only disadvantage of this scheme is the 30-V biasing voltage that the diode requires. Capacitors C1 and C2 couple the Philips BB909A variable-capacitance diode to the 745124.
This circuit uses the output of the IGL8049 to control the frequency of the IGL3038 waveform generator; the 741 op amp is used to linearize the voltage-frequency response. The input voltage to the 8049 can be, for example, from the horizontal sweep signal of an oscilloscope; the output of the 8038 will then sweep logarithmically across the...
This simple circuit can convert a single supply voltage, such as a battery, into a bipolar supply. Sense resistors Rl and R2 establish relative magnitudes for the resulting positive and negative voltages. Their rail-to-rail value, of course, equals VsUPPLYÂ· R4 and R5 represent the load impedances. For example, equalvalue sense resistors...
At startup, the voltage in the trigger input at pin 2 is less than the trigger level voltage, "13 VDD. caus ing the timer to be triggered via pin 2. The output of the timer at pin 3 becomes high, allowing capacitor c, to charge very rapidly through diode Dl and resistor Rl. When capacitor C, charges to the upper threshold voltage 2 /3 V00, the...
The output frequency of the VCO, U1, varies inversely with the input voltage. With a 1 "V input, the oscillator output frequency is about 1500 Hz; with a 5-V input, the output frequency drops to around 300 Hz. The output frequency range of U1 can be altered by varying the values of C1, R2, and R3. Increasing the value of any those three...
Video Line Bar Generator Circuit
A 555 and a dual 556 timer generate a rudimentary video signal, as shown in the schematic. The first timer generates 4.7-8 synch pulses operating in the astable mode with a 64-8 period. The second timer generates a delay pulse, which triggers the third timer to generate a bar,
Sinusoidal 3Hz To 300Khz Vco Circuit
This circuit uses Analog Devices` AD639 universal trigonometric function generator to convert a triangle waveform, the basic waveform of the VCO itself, into a very low-distortion sine wave. By using the AD639 in its frequency tripler mode , the frequency range 3 Hz to 300 kHz is now covered. The circuit has been drawn here--so that the...
Vco Circuit Circuit
The output frequency of this simple low-cost active voltage-controlled oscillator circuit is based upon the inherent frequency dependent characteristics of our operational amplifier. The oscillator circuit shown uses a TL082 op amp. When power is applied, the circuit generates a sinusoidal wave.
Voltage controlled ramp generator
The current source formed by Ql in conjunction with capacitor Cl set the duration time of the ramp. As the positive dc voltage at the gate is changed, the peak point firing voltage of the PUT is changed, which changes the duration time.
A Colpitts VCO for Wideband (0.952.15 GHz)
Modern set-top DBS TV tuners require high performance, broadband voltage control oscillator (VCO) designs at a competitive cost.To meet these goals, design engineers are challenged to create high performance, low-cost VCOs.
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.
µC-based circuit performs frequency multiplication
The traditional frequency multiplier requires many elements: a phase comparator to detect the phase error between the input and the output signals, a lowpass filter to convert the phase error to a dc control signal, a VCO to generate the output, and a divider to set up the multiple ratio. The circuit in Figure 1 uses a different approach to...
µC forms FM oscillator
A project required an inexpensive oscillator whose frequency increased step by step from 200 to 400 Hz and then decreased to 200 Hz. The first step was to design a VCO with a staircase driver. However, this approach entailed at least four ICs and many discrete components. An alternative method (Figure 1) requires only one 16-pin µC (an...
Circuit allows high-speed clock multiplication
In theory, synchronous clock multiplication is an easy task. A simple PLL with two digital dividersone inserted just after the VCO (voltage-controlled oscillator) and the second one placed directly at the input of the phase detectormay do the job. The flexibility of such a configuration allows for clock multiplication by any rational number.
Clock-recovery scheme suits low-SNR systems
A clock-recovery architecture can operate with NRZ digital signals, even at low SNRs. A clock-recovery subsystem is based on a PLL comprising a phase comparator, a loop filter, and a voltage-controlled oscillator (VCO).
LED driver as fault monitor
Using just four transistors and six resistors, this circuit provides switchable, constant-current drive for an LED and indicates both open- and short-circuit fault conditions (Figure 1). And there`s a bonus, too. Control signal VCONT switches the LED on and off. When VCONT is high, Q1 and the LED are off. When VCONT is as low as 0V, Q1 turns on...
Processor`s PWM output controls LCD/LED driver
The circuit comprises simply the PWM source, capacitor C, and resistors RD and RW. For CMOS circuits, you calculate the open-circuit output voltage as VCONT=D½§VDD, where VCONT is the control circuit`s output voltage, D is the PWM duty cycle, and VDD is the logic-supply voltage. The control circuit`s output impedance is the sum of the...
Circuit tests VCOM drivers
Flat-panel LCD monitors offer excellent image quality and more compact form factor than CRTshence, their steadily increasing popularity. Unfortunately, the complexity of their manufacturing process makes LCD monitors considerably more expensive than CRTs. The amplifier that drives VCOM, the voltage on the backplane of the LCD panel, must be able...
NTE789 Stereo Multiplex Decoder
Figure 1 shows the block diagram for the NTE789. The input signal form the detector is amplified by a lowdistortion preamplifier and simultaneously applied to both signal, generated by a local voltagecontrolled oscillator (VCO), is counted down by two frequency dividers to a 38kHz signal and to two 19kHz pilottone supplied by the FM detector...
Wave Multiplier for music synthesizers
For the primary multiplier, the "folder", connect the input to the triangle wave output of a VCO. Connect a LFO, envelope generator or even a DC voltage to the folds input. The result will be a harmonically rich signal at the "F out" output. A second input based on a lag circuit allows square waves and other hard-edged waveforms to be used as...
Inverters form three-phase VCO
The inspiration for the VCO in Figure 1 came from Texas Instruments application notes of years ago, detailing the use of unbuffered U-type inverters for use in ring oscillators. The application notes circuit consists of only the inverters. The circuit generates relatively squarish waveforms. Any ring oscillators operation depends on the...
VCO produces output frequencies
The circuit in Figure 1 is a quadrature-output VCO that provides both positive and negative output frequencies, depending on the polarity of the control-voltage input. The circuit provides a function that designers traditionally implement in analog music-effects units, such as Bode/Moog frequency shifters. Bode/Moog shifters use...
programmable logic VCO
A VCO (voltage-controlled oscillator) is an analog circuit, so you cannot find it in the libraries for the design of digital programmable chips. When you need such a circuit for synchronization or clock multiplication, you need to find a circuit that works with the standard digital functions, such as AND and NAND. Several possibilities exist for...
Multilayer capacitor doubles as varactor
The circuit is also an inexpensive VCO (voltage-controlled oscillator) with only five components. Many types of ceramic capacitors for surface-mount placement are on the market. The parts become continually smaller because of space problems on the board, and the capacitance values continually increase to compete with more expensive...
Voltage programmable square wave generator
Here's another daft yet interesting PIC12F675 idea I came up with. When I wanted to show someone how logic gates worked I could only find a NAND gate which wasn't very handy for demonstrating AND's OR's, NOR's and ExOR's. I also wanted to have a play with the A/D converter on the 12F675 so I came up with the idea of a PIC that could function as...
200mW FM transmitter
Here is the latest and greatly improved TX200 VFO/VCO FM transmitter. The most versatile transmitter to date that can be turned into high fidelity stereo PLL based 200mW FM transmitter. It is a perfect circuit for transmitting your music around the house and yard. TX200 uses only two coils; one in the oscillator and the other one in the 200mW...
VCO with NE567
Who would like to build a sidetone oscillator with a minimum amount of parts should try the NE567 integrated circuit. The NE567 is a PLL circuit with an internal VCO for a operating frequency less than 500 kHz and it is normally used as an audio tone decoder. The VCO frequency is adjustable by two passive components only. For a 750 Hz sidetone...
1.2GHz Voltage Controlled Oscillator With Linear Modulation
Since high frequency voltage-controlled oscillators, or VCOs, are not easy to construct, Maxim ( has produced an integrated 1. 2GHz oscillator, the MAX2754. The center frequency is set using the TUNE input, and a linear modulation input allows the frequency to be modulated. The IC is available in an 8-pin µMAX package, operates from a supply of be
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Low Cost Pulse Generator circuit
This pulse generator produces square pulses from 1Hz to 100KHz with adjustable pulse width of nearly 0-100%. The generator is powered with a voltage of 5-15V and is therefore suitable for both TTL and CMOS circuits. If you want to measure the response of an amplifier or give timing pulses to a variable frequency digital circuit or drive a pulse...
Key Code Combination High Security Door Lock
This project is an electronic lock with many combinations that you can easily change and opens only with the correct combination of four consecutive numbers. The big advantage of the electronic lock is that the four numbers must be entered in the correct order one after the other. If a number is wrong then the circuit automatically resets to its...
Induction Balance Gold Metal Detector Circuit
This circuit really is the simplest inducer balancing metal detector (IB, Inductlon Balance) that can be built. The LB metal detection method has a satisfactory depth of penetration and good distinction between iron-based and noble metallic objects. Several metal detectors are available in the market, but their price is often prohibitive for...
Secret High Power Free Energy Circuit (AEC)
This is a Tesla/joule thief hybrid circuit that its inventor claim to produce 90 times the input power! The circuit can be self looped and can provide 1050W of power. from the 1050W only the 11.6W will loop back to supply the joule thief. If you remove the bridge rectifier and the C capacitor you can use the circuit with high frequency AC...
High Power Full Bridge Flyback Driver circuit
You need to find a reliable full bridge driver to drive your flyback transformer? Well, This is your final stop. There are many flyback drivers schematics out there, but most of them will not last for long. It is common known that famous ZVS invented by Vladmiro Mazilli, is the most reliable flyback driver as it uses the resonant zero voltage...
High Precision Digital Pulse Meter Circuit
This small device, intended primarily for modellers, allows an instant reading of the time I of a pulse in ms. It can, for example, measure the position of the servomotors, about 1 to about 2 ms, or make repetitive or non-pulsed measurements, such as closing or opening times of any instrument, parasitic abnormality. The diagram just describes...
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