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VCO modulating voltage input

electronicNovice

Jul 26, 2015
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I have RF VCO module. I have 2 inputs Vcc (Power supply at 5V). Then I have modulating signal 0-4.5V. What should I do with the modulating signal? Can I short it to the GND (The GND on the VCC)? What is the modulating signal for? It is 1.2GHz VCO module. I need the VCO to be in the Box. It is not for a bench testing. If anybody have a reference for VCO book or manual that would be great.
Thanks
 

bertus

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Nov 8, 2019
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Hello,

Do you have a datasheet or other detailed info on the module?
I would take two resistors to make a voltage divider, to fix the modulation input on a fixed value, inside the range of the mentioned 0-4.5 Volts.

Bertus
 

electronicNovice

Jul 26, 2015
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I do not have a datasheet. But what is the modulating signal for? Should be ac or DC?? I can bring DC signal to it no problem. With a separate battery or same battery with voltage divider as you suggested.
 

bertus

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Hello,

Where did you get the VCO module?
What is the frequency range?
The modulation input is likely to shift the frequency of the module, like FM modulation.

Bertus
 

electronicNovice

Jul 26, 2015
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Hello,

Where did you get the VCO module?
What is the frequency range?
The modulation input is likely to shift the frequency of the module, like FM modulation.

Bertus

Ok. If I ground it then should be fine also right?? Because then the modulation will be zero (like f + delta (f) = f )
 

bertus

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Hello,

I would expect the voltage be the half of the range, so about 2.25 Volts.

Bertus
 

Harald Kapp

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Do you know what a VCO is?
A VCO is a voltage controlled oscillator. Meaning that you change the frequency by applying a control voltage. When you fix the control voltage anywhere within the allowed range (0 V ... 4.5 V) the frequency will be fixed, too.
You will find the relationship between control voltage and oscillator frequency in the VCO's datasheet.
 
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