ok, well we tried an experiment altering a voltage signal by using a potentiometer and while we succeeded in having an effect similar to our hypothesis, it was in fact the exact opposite reaction we were expecting.

It is now apparent that to achieve the desired effect, we need to take the signal voltage, and boost it by an extremely small amount.

Many of the boosters i've run into trying to figure all this out, are to make like 3 volts 12 or whatever, multiplying the voltage by factors of 2-4. I need like to multiply it by a factor of like 1.05 or 1.1

the voltage signal we are trying to modify varies from .1v-1v, and fluctuates between a high and low point. The device monitoring the voltage then averages the high and low point to make an average center point.

We are trying to skew the input being received by the device so that the center point (as perceived by the device) will be slightly higher than it would be reading the original signal, while preserving the scale of the low and high points.

As stated, when we reduced the signal voltage, the center point slid down the scale.

How can I do this?? Ima NOOB!

HELLLLLLP!

 

I was told by a local non radio shack electronics supply place, that because of the extremely low voltage of the signal voltage, most conventional (simple) solutions would not work well.

 

An op amp will do what you want, but do you want gain of 1.1 which will streach the signal such that instead of .1 to 1 volt you have .11 to 1.1, a difference of .99 volts instead of the original .9 volts. Or, would an offset of .1 volts such that the output is .2 to 1.1 which preserves the .9 volt difference be better?

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We are looking for the simplest method available. It sounds like the first scenario you stated will work for us just fine... I'm googling op amp.

 

Ok, i dont think so. it says an op amp has a negative and positive output, i need a constant output.

http://www.hobbyprojects.com/operati...with_gain.html

whats this? any comments?

 

An op amp seems to not be ideal as i read, "The output on pin 6 switches (repeatedly) from positive to negative"

That sounds like it will not work. I cannot have an output of .8 volts one moment, and -.8v the next. It seems a "non inverting amplifier" may be what i need?

 

Well your post makes very little sense, and it's hard to know what you've got and what you want - try posting a circuit of what you've got so far, and tell us EXACTLY what you're trying to do (and not how you're trying to do it).

But as suggested, based on the meagre information so far, an opamp should do what you want?.

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This is the kind of thing you need:

Attached Images

OP AMP.jpg (12.4 KB, 17 views)

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Don't liston to what they tell you at Radio Sh@g, they don't know what they're talking about!

They're only shop workers, they don't know anything about electronics!

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http://www.stop-microsoft.org http://www.heated-debates.com
Screen name: Aloone_Jonez
And http://www.silicontronics.com, same screen name as here.

 

I know I asked one if he had any background or training in electronics.... He said he was a former schoolteacher, lol

 

Whats your deal? I saw you posting this EXACT post to someone else's thread. Do you have it like on a preset or somthing? I'm a noob at this, i was even having a difficult time getting this forum to work, so please go easy on me.

I think i made it perfectly clear what i need, as others have been able to lend kind assistance from whatever non technical information I have provided.

 

And finally, RusselK!

You are the man. Thank you so much for helping me through this, your answers have helped me more than i can tell you. I have found similar diagrams, but i really dont understand a lot of things i am reading about this circuit.

Will it be able to provide the circuit with a constant voltage boost?

can anyone provide me with some basic knowledge about what is happening in the diagram russelk here has provided? I will be much more comfortable working on this if i feel i have a grasp of the big idea

like this.... i wasnt much into algebree in the high school..

R2
Vout= Vin ( 1+ --- )
R1

but then it says Zin=infinity

I dont see a z in anywhere

then it talks about a third resistor of value Rf||Rin added between the Vin source and the non inverting input

If you are confused, i am looking at the wikipedia entry for "operational amplifier applications.... here, http://en.wikipedia.org/wiki/Operati...r_applications

I'm confused by ALL of this, so any help, would be AWESOME!!

 

A typical exchange after walking into Radio Shack:


"Can I help you?"

"No, I know more about what I'm looking for than you do..."

 

I remember (when I was a child) asking a shop assistant at Maplin how many transistors one of the melody generators they sold contained, they said "about 20". I don't think so they were just giving me the usual bs!

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Screen name: Aloone_Jonez
And http://www.silicontronics.com, same screen name as here.

 

The input impedance of the op amp is high already (megohms) and is multiplied by some factor of the gain which makes it so high it would be difficult to measure. There is bias current at the input, about 100 nA which is small enough to neglect in this circuit. Where the Wikipedia article says Rf||Rin, it should have said R1||R2. But, again, the bias current is neglectable. There will be several millivolts offset at the output which can be trimmed out but might require a negative voltage.

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