Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

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 expensive and feels like overkill. I was looking at…
bcattle
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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 without a lot of additional circuitry. 555 VCO I've…
blarg
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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 oscillator as being harmonic or relaxation. I'm…
Saunders
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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 power supply I get waveform output for about half a…
NBoss
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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 human hearing) to the frequency to which it's been…
Rob Kam
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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 it looks at the limits of audible threshold: I…
somerandomusername
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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?
gj13
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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 the voltage present at the base of Q7. This…
Mike Spivey
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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 of this VCO. However, when it's connected to a…
alkopop79
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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 as seen in a breadboarded version before), the…
Aaron Kimball
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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 is used between the phase detector and the VCO to…
Matt_LDN
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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 input and output clock frequency and phase. I…
cplusruss
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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 VCO (for modular synthesizer) using only…
wurly
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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 the "GND". In my understanding, Vcc is the positive…
hohohoman
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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 they mean one of the two op amps that are inside…
Kunal Verma
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