VWhat output should I expect from my operational amp circuit using UA741?

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Discussion Overview

The discussion revolves around the design and expected output of a circuit using the UA741 operational amplifier (op-amp). Participants explore the appropriate input sources (AC or DC), gain configurations, and the implications of power supply voltages on output levels.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant inquires whether to ground the unused inputs and whether to use AC or DC sources for the op-amp circuit.
  • Another participant asserts that a DC source should always be used to power the op-amp and suggests consulting the datasheet for guidance.
  • There is a question about which input configuration to use to achieve a specific output equation (Vout = 66v1 + 1100v2 + 550v3).
  • Participants discuss the implications of using AC versus DC inputs, noting that AC inputs would require a negative power supply.
  • One participant mentions that the output is limited by the power supply voltage, indicating that if a +5V supply is used, the output cannot exceed +5V.
  • Another participant confirms using +/- 12V to power the op-amp and reports obtaining an output of 11V with 1V DC at each input.

Areas of Agreement / Disagreement

Participants express differing views on the appropriate input sources (AC vs. DC) and configurations for achieving the desired output. No consensus is reached regarding the best approach or specific values for inputs.

Contextual Notes

Participants reference the need for specific input values and configurations without resolving the dependencies on the circuit's design and the op-amp's characteristics. The discussion includes assumptions about the power supply and input types that remain unresolved.

Who May Find This Useful

Individuals interested in operational amplifier circuit design, particularly those working with the UA741 op-amp and exploring gain configurations and input source implications.

EEStudent
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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..
 
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edmondng said:
in this single or dual op amp? ALWAYS use DC source to power op amp.

the datasheet should be helpful
http://www.st.com/stonline/products/literature/ds/5304/ua741.pdf

Connect the way you want for the gain (ie: inverting/non-inverting etc...)
thanks for the help..
the gain is high so which input should i choose to get 66v1+1100v2+550v3
 
http://img91.imageshack.us/img91/8356/opamp1hp2.jpg

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

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 that's 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
 
edmondng said:
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 that's 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
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
 

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