Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

Questions tagged [varicap]

13 questions
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2 answers

1977 GE 6RS20SP9B9 - what the heck is this component?

Ok so, ordinarily I'd not ask a "what is this" question, but this component really has me scratching my head - both at its function in the circuit and how it is constructed. Anyone know what a GE 6RS20SP9B9 axial device, circa 1977, is? The only…
rdtsc
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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 varicap diodes and a resistor perpendicular to the…
Mr X
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3 answers

Multi-tuning AM selector

I'm thinking about the design of an AM receiver frontend that needs to select between three channels. The community suggested that I investigate manually wound loop antennas, and they seem like a nice choice. AM loop antennas are designed for…
Reinderien
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2
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1 answer

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 done? Thanks in advance
user3120921
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Is BBY40 a good substitute for MV209 in this RF receiver?

VD1, indicated by the red circle in this is a varactor diode and the suggestion given for the varactor diode in this manual is MV209. It seems to be outdated and so are many other components. How do I find good substitutes? Why is a varactor diode…
Mathav Raj
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Using a varactor diode to tune a resonance frequency

I think this is a question is some very elementary circuit design but... I want to use a varactor diode to tune the resonance frequency of a resonator I have built. I understand that a varactor is a voltage dependent capacitor, but I can't get my…
user27119
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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 don't know what is the problem with the…
SMA.D
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1 answer

How to adapt a FM reciever circuit to use a varicap diode instead of a trimmer capacitor

My team and I are interested in learning about FM communication and decided to build a simple FM receiver before building a proper transmitter. We looked at some circuits on the web, and they all seem very similar. The problem is that these circuits…
Candy Hi
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Can anyone help me in designing this variable frequency colpitt oscillator?

I am basically trying to achieve a variable frequency colpitt oscillator by using a varactor diode to achieve frequency change. However, I am having trouble figuring out how to connect it so that it does not affect the output voltage. As you can…
needbrainscratched
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How to define the circuit that replaces the variable capacitor in its use with the TDA7000?

In the circuit below, there is a subcircuit that connects between C4, D1 and the VCC (5V), with Q1 and D2 as the central component, this circuit seems to me to be a Gyrator, I know that Gyrators are a choice to replace coils, however here it…
Delfino
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How can I create a varicap in ADS?

I need to create a varying capacitor, so I'm trying to make a varicap in ADS. However, there are only diodes, and I don't know how to make a varicap. Can you point me to some resources or walk me through this? I'm also fairly new to ADS. Thanks
JobHunter69
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How to boost (double voltage) a sawtooth generator

I have a circuit to drive, using a sawtooth generator, four varactor diodes (FC54). These varactor diodes has the following specs: from 2.5pF (at 15V) to 30pF (at 0V), but my sawtooth generator, based on an NE555 (feed at 12V) is only able to give a…
Giov
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Can you switch between 2 tank circuits using a relay?

Say I have an oscillator that needs to span between 1 GHz and 1 Mhz. Ill be controlling it with a microcontroller, probably an arduino. According to this, http://faculty.mu.edu.sa/public/uploads/1400394697.1447Ch16%20-%20Oscillators.pdf, there are…
user2455722
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