Building a Voltage-Controlled Amplifier with Components

[tics]

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

Homework Statement

"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

Homework Equations

non-inverting gain equation,

The Attempt at a Solution

I tried to build a non-inverting amplifier and inserted a volatge-divider to make it an amplifier.

Homework Statement

Homework Equations

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

The Attempt at a Solution

 

[sciencebabe]

which university of technology do you go to?

 

[berkeman]

Homework Statement

"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

Homework Equations

non-inverting gain equation,

The Attempt at a Solution

I tried to build a non-inverting amplifier and inserted a volatge-divider to make it an amplifier.

Homework Statement

Homework Equations

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

The Attempt at a Solution

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?

 

[tics]

Thank for your reply.The JFET=2N3819.

 

[DeeNos]

I would like to address the content of building a voltage-controlled amplifier with components. This is a common task in the field of electronics and can be achieved by using an operational amplifier (in this case, the 741 model), a capacitor, and a variable resistor.

Firstly, it is important to understand the concept of a voltage-controlled amplifier. This type of amplifier has a gain that is controlled by an input voltage. In other words, the output voltage of the amplifier is directly proportional to the input voltage. This makes it a very useful tool in electronic circuits, as it allows for precise control of the amplification level.

Now, let's analyze the attached circuit. One important aspect to note is the connection of the JFET gate to the negative supply. This is known as a common-source configuration and it allows for a high input impedance, making it suitable for voltage-controlled amplifiers. The JFET acts as a voltage-controlled resistor, with its resistance changing based on the input voltage. This, in turn, affects the gain of the amplifier.

The components that determine the gain of the circuit are the resistor and the JFET. The gain can be calculated using the non-inverting gain equation, which is (1+R2/R1). In this case, R2 is the variable resistor and R1 is the resistance of the JFET.

The ohmic region of the JFET is important in this circuit as it allows for a linear relationship between the input voltage and the output voltage. If the JFET is not in the ohmic region, the output voltage will not be proportional to the input voltage, and the amplifier will not function correctly.

To make an amplifier from a non-inverting amplifier, we can simply add a voltage divider to the input. This will allow for control of the input voltage, which in turn will control the gain of the amplifier.

When building this circuit, it is important to pay attention to the component terminal connections. The positive and negative supply terminals of the operational amplifier should be connected correctly to the power source, and the JFET should be connected with the correct polarity. It is also important to consider the maximum power ratings of the components to ensure they can handle the voltage and current levels in the circuit.

In conclusion, building a voltage-controlled amplifier requires a good understanding of the components involved and their functions in the circuit. By carefully considering the JFET connection, the gain equation, and the