so the output will not be the input plus the boosted amount? what is offset?

 

---Insert remark about who you are/where you live/race/gender/employment here---, but then that would be a stereotype. Maybe you should think before grouping all RS employees into your stereotypical belief about them. RS does not train its employees on circuit theory. The components are in the parts drawers and you should know what you need. There are even pictures on the front of the drawers if you can't read. I will agree with you that most RS employees do not know the first thing about building a circuit, but you have to keep in mind that they are not trained to be your electrical engineer for your project, they are salesmen/women. If they cant point you in the right direction for what you asked then they are either new, or maybe stupid; but don't go saying no-one at RS knows anything about electronics because that just isn't true. I work at RS and know a hell of a lot about electronics and microcontrollers. I couldn't see making a career of it, but to help pay bills during college to get an electrical engineering degree it is not a bad place to work. ( discount on what little parts RS still sells ) Sorry to hijack your thread evotec, but I couldn't let this one go. This isn't a personal attack Hero, I'm just sick of the lumping of all RS employees into one pile of idiots. -Jacob

 

ok, this isnt a buzzing RS post, its a help i'm a noob post... any explanations of what russlk said?

 

evotec, from your original question, this is how i interpreted it. Your signal has a range of 0.1 to 1.0 volts. Your device reads this voltage over some time period and then gives your the median value of all values recorded(center point). While setting the gain of the op-amp at 1.05 or 1.1 as mentioned would probably work, you might try setting the op-amp up as a 'non-inverting summer'. Take your actual signal voltage and the amount you wish to shift your signal, and add them together. Say your shift voltage was set at 0.2 volts, the range of the output signal would then be 0.3 to 1.2 volts. This would only shift your signal voltage instead of multiplying it. Check out this link for more info and diagrams. Make sure to set the gain at 2 instead of 3. Their examples show summing 3 voltages. http://www.allaboutcircuits.com/vol_3/chpt_8/8.html -Jacob

 

Awesome! I'm checking it out.

 

You might also want to read the sections to the left before the averager and summer section to better understand how an op-amp works and how to set the gain. -Jacob

 

The reason why I bash RS salespeople is their company chooses NOT to educate the employees. There are consumer electronics corporations that do and it is a great thing to see. If you come around my part of the country, walk into a Magnolia Hi-Fi and be amazed...

 

i agree.

 

TheVictim, what part of the country are those stores in? Ive never even heard of them

 

We got one here i tacoma, mostly high end electronics i thought

 

Yeah they are, but just TRY and stump one of their people with a complex audio, video, or wireless question. They go through WEEKS of training.

 

ok, in the diagram on page "http://www.allaboutcircuits.com/vol_3/chpt_8/8.html " under the section about "noninverting summer circuit" there is a value for R that is equal, and placed on all 3 of the input voltages.

Can this resistance value be anything, such as nothing?

If not, How can I calculate an appropriate resistance for this value?

 

Yes, you can have as many or as few summing inputs as you want. The gain for each input is Rf/Rin.

__________________
see my website: www.geocities.com/russlk

 

thanks for the input, you guys really know your stuff!