Questions: 5v Signal Manipulation w/ Circuit

[Live4Redline]

Is it possible to build a circuit with some sort of switch or dial so that it outputs with some sort of + or - gain to the voltage. If for instance the input is reading 3v, i can turn the dial so that it reads 1v, or 2v, or even 5v. The input is going to be a fluctuating 0-5v so the output will need to be able to fluctuate with the changes. Changing an incoming reading of "2,3,4,5v" into "1,2,3,4v" or if its +gain "3,4,5,5v". The change doesn't need to be 1v exactly... just able to be dialed up or down.

This is for a small personal project i am working on. I have a basic knowledge of circuit building and i am just looking for someone to point me in the write direction if you can. I would really appreciate it and thank you.

 

[Les Jones]

Hi,
The example you give are not adding gain (Which means multiplying the input value by a constant to provide the output.) In the first example you are subtracting 1 volts from each input value to get the output value. In the second example you are adding 1 volt to each input value. Weather you want to multiply the input value or add/subtract to it an operational amplifier integrated circuit together with a few resistors will do the job.

Les.

 

[alec_t]

The input is going to be a fluctuating 0-5v

How fast are the fluctuations?
How much current must the converter provide?

 

[AnalogKid]

Les makes a good point. For your question there are two ways to adjust an analog signal. One is with gain and the other is with offset

Gain is a multiply/divide process. 1, 2, 3, 4 with a gain of 2 produces 2, 4, 6, 8. 1, 2, 3, 4 with a gain of 0.5 produces 0.5, 1, 1.5, 2.

Offset is an addition/subtraction process. 1, 2, 3, 4 with an offset of 2 produces 3, 4, 5, 6. 1, 2, 3, 4 with an offset of -0.5 produces 0.5, 1.5, 2.5, 3.5.

Which of these is what you are trying to achieve?

ak

 

[Live4Redline]

Hi,
The example you give are not adding gain (Which means multiplying the input value by a constant to provide the output.) In the first example you are subtracting 1 volts from each input value to get the output value. In the second example you are adding 1 volt to each input value. Weather you want to multiply the input value or add/subtract to it an operational amplifier integrated circuit together with a few resistors will do the job.

Les.

I'm reading up on the operational amplifiers, thanks.

How fast are the fluctuations?
How much current must the converter provide?

I hate to be vague but I'm not sure exactly. The fluctuations are slow enough to eye witness at the tenth of a volt but not at the hundredth if that makes sense. Its a 12v DC setup with a fixed input range of 0v-5v and a needed fixed output max range of 5v.

Its just that while at full cycle if the highest peak voltage i see is 3v on the input for instance, i need to be able to manipulate it (with a dial or switch of some sort) so that on the next cycle the peak input will be changed so that the peak output reads 3.5v or 4.0v instead. Several cycles later, it may need to be adjusted lower or even higher again.

Les makes a good point. For your question there are two ways to adjust an analog signal. One is with gain and the other is with offset

Gain is a multiply/divide process. 1, 2, 3, 4 with a gain of 2 produces 2, 4, 6, 8. 1, 2, 3, 4 with a gain of 0.5 produces 0.5, 1, 1.5, 2.

Offset is an addition/subtraction process. 1, 2, 3, 4 with an offset of 2 produces 3, 4, 5, 6. 1, 2, 3, 4 with an offset of -0.5 produces 0.5, 1.5, 2.5, 3.5.

Which of these is what you are trying to achieve?

ak

From what I'm reading on the subject... offset is what I'm after. Also, thanks on the explanation of both.

 

[alec_t]

Something like this?

The yellow curves show the output (for a 0V to 5V input) for various settings of the pot.

 

[Tony Stewart]

If you define your process, there may be a better way to control it automatically with feedback.