op amp input

[Jim_in_Oceanside]

I need a simple summing amp to output varying 0.1VAC to 4.5VAC with a -7.5VDC bias.
I looked up some information on the web and built a 741 summing amp. My problem is that the AC loses about 0.5 volt at the output. I expect 1/1 gain with a little loss, but not that bad. Then I replaced the 2-6 10K feedback with a trimmer. When I set the feedback away from 10K, the VAC basically goes away. I expected setting FB >10K would increase my output AC and DC.
Any ideas what I am doing wrong?
Thanks
Jim
------------

741 opamp

+12VDC on 7, -12VDC on 4


4.5AC 10K 10K FB (tried a pot here, also to inc gain)
--/\/\/\--+--/\/\/\--+
| |
7.5DC 10K |2|\ |
--/\/\/\--+-|-\ |

| \ 6 | 100K
| >----+-----/\/\/\-----
3| / |
-------|+/ |
| |/ |
| -----
| ---
| -
|
-----
---
-

[Jim_in_Oceanside]

My problem with this is that I did not have enough power supply voltage. It was clipping when I increased the gain.

[Jay.kothari]

Attach your VI so that we can work on it

[JÞB]

Jay,

Why bump a 9.5 year old resolved offtopic post?

[Jay.kothari]

Jeff Bohrer,

                Hahahah. Sorry I was looking for a VI on OP- AMP circuits. Did not take care about the date. Do you have a working VI o OP-AMP 741

[JÞB]

OK What do you want the VI to do?  VI= Virtual Instrument,  the 741 is hardware that has no IO for software to control.

-Very confused

[Jay.kothari]

Sir,

     I want to use OP-AMP in its basic applications. I want to use it as an amplifier, iventer, adder, Subtractor, Schmitt Trigger, and other basic applications which u come across durig your undergrad course.
Do you have any such VIs related to Op-Amp,diodes,transistor,IC 555 etc

Jay

[Dennis_Knutson]

It sounds like you need Multisim. LabVIEW is a programming language - not a circuit emulator.

[Jay.kothari]

No No. I need it on LabView.. I need to implement on LabView. I am aiming to develop an educational tool for my college to help students. MultiSim is easy wherein the functions and working of each too is pre metioned. I want students to understand the basic concepts like even from formula point of view.