# Homework Help: VOLTAGE-CONTROLLED AMPLIFIER . I am required to build a voltage-controlled amplifier

1. Feb 4, 2010

### tics

"VOLTAGE-CONTROLLED AMPLIFIER". I am required to build a voltage-controlled amplifier

1. The problem statement, all variables and given/known data
"VOLTAGE-CONTROLLED AMPLIFIER". I am required to build a voltage-controlled amplifier,using:
1 operational amplifier(741), 1 capacitor between 1 to 10 microfarad(Electrolytic polarised or non-polar), 1 variable resistor.
I need help to analyse the attached circuit with the aid of the following:
notice how the JFET gate is connected to the negative supply. Why is that?
Which components in the circuit determine the gain of the circuit? how does an ohmic region affect an amplifier?
What is the equation of for the gain of the projct circuit in terms of the components in the circuit? how do you make an amplifier from a non-inverting amplifier?
Provide info regarding component terminal connections, max. power ratings
2. Relevant equations
non-inverting gain equation,

3. The attempt at a solution I tried to build a non-inverting amplifier and inserted a volatge-divider to make it an amplifier.
1. The problem statement, all variables and given/known data

2. Relevant equations
Id=Idss[1-Vgs/Vgs(cutoff)]*2

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

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2. Feb 4, 2010

### sciencebabe

Re: "VOLTAGE-CONTROLLED AMPLIFIER". I am required to build a voltage-controlled ampli

which university of technology do you go to?

3. Feb 4, 2010

### Staff: Mentor

Re: "VOLTAGE-CONTROLLED AMPLIFIER". I am required to build a voltage-controlled ampli

Welcome to the PF. That's a bit of a strange connection, but what property of the JFET do you think they are using in that connection?

4. Feb 5, 2010

### tics

Re: "VOLTAGE-CONTROLLED AMPLIFIER". I am required to build a voltage-controlled ampli