# Design with operational amp

1. Feb 19, 2008

### EEStudent

I am designing a circuit using ua741 opamp to obtain a gain, in order to get a output on one of the inputs such as V1 should I ground the other two inputs and have a 0 voltage on ac or dc and also should I use ac or dc source because the professor did not specify..

2. Feb 19, 2008

### edmondng

3. Feb 19, 2008

### EEStudent

thanks for the help..
the gain is high so which input should i choose to get 66v1+1100v2+550v3

4. Feb 19, 2008

### EEStudent

http://img91.imageshack.us/img91/8356/opamp1hp2.jpg [Broken]

i know to power opamp i use dc.. but at the input should i use the dc or ac source and based on my calculations i got 66v1+1100v2+550v3
what should i use for v1,v2,v3.. if dc what should the value be and if ac what should the value be at these nodes.

Last edited by a moderator: May 3, 2017
5. Feb 19, 2008

### edmondng

what are you trying to accomplish? are you trying to get Vout = 66v1+1100v2+550v3? What output do you want? DC?AC? AC+DC? Your output depends on input.

v1, v2 and v3 are inputs. you can put in anything and get some output based on the gain of the system. if you put in AC then you have some sine equation as v1.

i suppose if the equation vout = 66v1+1100v2+550v3, then thats your answer. Your op amp output can only put out so much as you supply it with. If you use +5V supply, Vout cannot be >5V because the op amp is clamp at 5V. If you supply +12V then it is clamp at +12V. Also if you put AC as input you will need a negative power supply.

Datasheet list the absolute max rating. Hope this helps

6. Feb 19, 2008

### EEStudent

I know it gets clamped.. I used +/- 12volts to power the opamp
and used 1v dc each at v1,v2,v3 so i got vout as 11