Questions tagged [vco]
VCO (Voltage-Controlled Oscillator) is an electronic oscillator whose oscillation frequency is controlled by a voltage input.
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How to design a cheap sine-wave generator up to 200 MHz?
I want to make a cheap wideband oscillator for an antenna analyzer I'm designing. I want a simple sine wave over a wide frequency range. I don't want to use a DDS IC like the AD9851 because it's ...
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VCO for synth V/Octave and battery supply?
It's been a dream of mine to build an analogue synthesizer for a few years.
In this time I've built VCOs based on the 555 timer, which I know do not generally have an accurate frequency response ...
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Does this VCO produce a sine wave or square wave
I'm looking at the datasheet for the analog devices hmc431lp4 voltage controlled oscillator, and I can't tell if its output waveform is a sine wave or square wave. The datasheet doesn't label the ...
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Design for an analogue oscillator that doesn't drift in frequency?
VCOs (Voltage Controlled Oscillators) in analogue music synthesizers are notorious for drifting with temperature. What design solutions are there for an analogue audio VCO that keeps close (as in ...
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Kickstarting an opamp for oscillating?
I have been building many different variations of op-amp oscillators but have come across a recurring issue that has manifested itself again in this VCO schematic:
I find that when turning on my ...
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What design should I use to clean up this pulse wave?
I'm using common voltage controlled oscillator IC - AS3340.
It has some problem with pulse wave output on higher frequencies. The bottom of falling edge looses sharpness the higher I go.
This is how ...
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Can I use a DAC to tune a VCO?
I found some FM transmitter circuits with the MAX2606 VCO.
Example:
Can I replace R1 with the DAC output from an AVR microcontroller? Or can I connect the DAC directly to Pin 3 of the MAX2606?
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Minimoog VCO analysis
The diagram shows part of the schematic for the late-model Minimoog VCO. In the circuit, Q7 and Q8 form a current sink, drawing a current through the collector of Q7 that is exponentially related to ...
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Struggling to understand how a phase locked loop reaches lock
I have a basic question regarding PLLs and how they actually achieve lock.
I was told that the PLLs go into the lock when the output of a phase detector is zero, therefore to drive VCO an integrator ...
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Grounding Vcc and Vee?
I recently started electronics as my hobby. I'm working on this v/oct modular synth and in the schematic that I was working on, it did not make sence to me when all the Vcc and Vee are connected to ...
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How do I make a VCO with a LM 358?
Hi! I am an absolute newbie at electronics (though an Industrial engineer by qualification). I discovered this diagram for a VCO from the datasheet for an LM 358. I assumed when they say 1/2 LM 358 ...
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How to debug unexpected behavior on voltage-controlled oscillator PCBA?
I designed a circuit for a voltage-controlled oscillator (VCO) for use in a synth and had it fabricated and assembled as a PCBA. I got three assemblies back and while two behave exactly to spec (and ...
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Phase relationship of multiple Fractional-N PLLs with same reference clock
I think I understand the general operation of PLLs in the case where a single reference clock generates a single output clock. Once the PLL is locked, there is a deterministic relationship between the ...
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Ramp/Pulse VCO - how to change the frequency?
I've successfully built this VCO circuit using an LM13700 that works just fine if the VC (the 510K resistor) is not connected to anything. Needless to say, I'd like to be able to change the frequency ...
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Tips on Building An Analog VCO
I am attempting to build an analog VCO. Many of the resources I see online implement a 555 timer, but I am trying to avoid that, solely for the sake of learning how to do this in purely analog. Here ...
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Sawtooth VCO DC offset issues
[Apologies in advance for possible misuse of terminology. I don't have any formal education in EE and am mostly self taught, so I may be lacking in some fundamentals.]
I am trying to design a discrete ...
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Problems increasing VCO frequency above datasheet recommendations
Firstly, yes I contacted ST for answers. Until now, no answer.
I'm using STM32F429 MCU and embedded USB FS PHY. To keep the 48 MHz USB PHY clock the maximum PLL clock that I can achieve is 168 MHz, ...
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Simple exponential converter for VCO
I need a simple exponential converter that with 9V and allows me to control a VCO. I've tried the one the schematics below but it needs bipolar power supply and just doesn't work. I have plenty of ...
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Can I make a VCO full audio range with only one capacitor?
I'm trying to make a VCO with a low voltage setup (3.3V), and i 'm using a mcp6002 op-amp. I'm controlling the frequency with an MCP4822 (dac). The problem is that i get a limited range of frequencies....
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How to Filter Harmonics in Wideband VCOs
I have a need for a RF signal generator, but I figured it would be a fun project to design a crude one myself. The main technical challenge I'm stuck on is how to filter out the harmonic content ...
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VCO circuit Analysis
can you help me with the basic comprehension of this Voltage Controlled Oscillator scheme (it was used in a PLL)?
I do not understand why there are two varactors instead of one, and the role of the ...
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An alternative way to make a VCO?
From what I am able to understand, a voltage controlled oscillator is "controlled by a voltage" when this voltage is applied to vary the value of the tank circuit: e.g. this could happen by applying ...
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VCO Input Capacitance
I'm trying to figure out the input capacitance of a VCO I am looking to use. The datasheet of the device does not specify an input capacitance. However, it does include the following. illustration
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How do I add a tuning potentiometer to modify the incoming control voltage of an XR8038?
I have been working on designing an analog synth and have decided to use an XR8038 as my VCO. If I wanted to add a tuning modifier would this configuration I made be okay?
P.S. Would I need to attach ...
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Generating sound with VCO
I have an extremely basic electronics experience (op amps, filters...not much past that) and need to generate sound from a varying voltage voltage signal. I simply want it to increase in frequency/...
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Simulating varicap diode in LTSpice
I have been looking into making a voltage controlled oscillator using varicap diodes, however I have had hard time simulating the diodes in spice.
Would anyone here have an idea how this would be ...
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How to send analog data using FM/FM Telemetry
I am measuring the strain a bicyclist is placing on a bicycle crank arm throughout riding, using strain gages. I would like to send this data (after amplification) off of the bicycle crank arm and to ...
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How do different octaves sound different in the presence of a low-pass filter in a synthesizer?
Per my understanding, when playing a certain pitch, say 440 Hz (middle C), the VCOs will produce their corresponding waveforms (say sawtooth) at that frequency. Because of the characteristics of the ...
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VCO SN74LS624 - understanding pin out / how to read datasheet?
I have a SN74LS624 chip and I am trying to get it working on a simple breadboard with an oscilloscope.
I have read the datasheet here: http://www.ti.com/lit/ds/symlink/sn54ls629.pdf
I can not ...
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Two details about phase noise have been confusing me for a long time. Hope to be resolved
Just like FLOYD M. GARDNER said in the PhaseLock Techniques, 3rd Edition: "In light of that success in spectrum analyzers, a practitioner’s answer to the question above is: The spectrum of phase noise ...
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Can Zener or Schottky diodes be used as a substitute for varicap diodes in tuning a VCO?
In particular, this would be a fairly low frequency VCO with a frequency range of 10 Hz to 20 kHz. I'm thinking of the configuration with the T-junction that has 2 opposite facing, reversed biased ...
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Problems Comparator II of this CD4046 for LTspice
I downloaded a CD4046B model from user ale_t, which can be found here:
https://www.electro-tech-online.com/threads/new-spice-model-for-cd4046b-phase-locked-loop-ic.149093/
However, the Phase ...
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How does VCO in PLL in computer processor work?
In todays personal computers and notebooks, what is usually used as a Voltage-Controlled Oscillator for generating clock signal for processor?
Is that a crystal rather than RC circuit?
Is it tuned by ...
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Voltage controlled oscillator with a MOSFET
Is it a good idea to use a normal MOSFET as a varactor for a variable signal generator?
For example:
I have an IRFZ44N and the datasheets says it has an input capacitance of 1470 pF. Can I use that ...
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Replacement for MC12149 (Voltage Controlled Oscillator)
I need to build up a VCO from 250-350 MHz. I have found an interesting IC called MC12149 from Motorola. However, it seems to be archived and no longer manufactured. Looking at the datasheet, it looks ...
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Should I be concerned with the higher current draw coming from a part of my circuit design, and if so, how should I limit it in my circumstance?
I'm designing a voltage controlled oscillator for a modular synthesizer. My planned range for this circuit is anywhere between 37Hz to ~20kHz. Here's a schematic of it I made with the Falstad ...
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VCO generating a lot of electrical noise, picked up by ultrasonic transducer
In my setup, I have a VCO CD4046 Phase Locked Loop IC generating a square wave, and an ultrasonic transducer set that transmits and receives that setup. You can imagine it looking something like this.
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FM modulator LTspice
I am designing an FM modulator circuit using Colpitts topology. Unfortunately I encountered difficulties and do not know how to solve them as I am new in electronics.
Firstly I don't get a clean sine ...
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Analog exponential convert for MFOS VCO
I'm trying to understand the exponential converter in the MFOS VCO. Here is a link to the complete MFOS Noise Box synth schematic.
http://musicfromouterspace.com/analogsynth_new/NOISETOASTER/...
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555 VCO Circuit - Speaker to VCC?
Hello!
I have a simple question concerning this circuit I have built:
It is a 555 Voltage Controlled Oscillator I have built as a foundation for my signal generator circuit. The circuit works great, ...
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How can I build a current controlled 50% duty cycle oscillator from two CMOS inverters?
I am in need of a current controlled audio range (output around 1000 Hz) oscillator/multivibrator circuit. To make the result sound nice, I want to oscillator to have a 50% or near 50% duty cycle. ...
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Low frequency in this VCO design
I am following this VCO design I found from a tutorial and for some reason the frequency is way too low. It doesn't state in the design what it should be, but following these instructions it is just ...
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Horn antenna for radar sensor
I have InnoSenT SMR-314 and SMR-334 radar sensors that have quite wide horizontal radiation pattern of over 100 degrees (see datasheet on page 3). I would like to make the sensors far more directional ...
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Control an inductive load with VCO
I am trying to tune this circuit, dimensioning the values of resistors Ra,Rb and the capacitor C... The circuit work in this way: a voltage Vin regulates the current flowing in the inductor, via the ...
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Sawtooth VCO and current source for modular synthesizer
I have been working on a current source and sawtooth core VCO based on the Electronotes/Aaron Lanterman/Ian Fritz designs/ideas.
I have breadboarded out the attached VCO schematic; the transistors ...
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How do I generate a high frequency sine wave using a PLL? 900 to 950 MHz
I know of a few ways to generate a sine wave; Op-amps, 555, LC, crystals, or microcontrollers. But none of those would really work for a frequency as high as 900 MHz. I have heard of phase lock loops, ...
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VCO doesn't work
I've tried to design a voltage controlled oscillator by adding a varactor to a Colpitts oscillator.
However simulation shows no change in the oscillation frequency as V3 changes (0.04v to 10v). I ...
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Colpitts VCO by varying base voltage
I've noticed that if I build a Colpitts oscillator (audio range) using a transistor in the common base configuration (similar to the circuit here) I can vary the voltage on the base and get a wide ...
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Question about the Verilog-A implementation of a VCO
I am learning verilog-A to model analog circuits. One of the examples given in the book is that of a voltage-controlled oscillator (VCO).
The book says the following about how the VCO can be modelled (...
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Why doesn't this 950 MHz to 2200 MHz Colpitts VCO circuit work in Multisim?
I found a 950 MHz to 2200 MHz Colpitts VCO circuit from this web page.
I tried to design it in Multisim, but doesn't produce any signals. Why?
I used BB130 diodes instead of SMV1232 because Multisim ...
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