Did I build my circuit correct on the bread board (pics)

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Discussion Overview

The discussion revolves around the correctness of a circuit built on a breadboard using an LM741CN operational amplifier. Participants evaluate the wiring, suggest modifications, and discuss power supply configurations. The scope includes technical explanations and troubleshooting related to circuit design.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • Some participants assert that the circuit is not wired correctly and suggest adding a capacitor to prevent high-frequency oscillations.
  • There is a discussion about whether both legs of a resistor being on the same node affects the circuit's functionality.
  • Concerns are raised regarding the use of power supply rails for input and output, with questions about better options for input and the correctness of the resistance configuration.
  • One participant notes the importance of a common connection for the power supply rails and specifies how the voltage divider should be connected.
  • Another participant explains the typical power connections needed for the op-amp, emphasizing the necessity of a common ground reference.
  • Some participants mention that the LM741 can operate from a single rail power supply, but caution that it cannot achieve full output swing from 0V to VCC.
  • There are suggestions for simplifying the wiring and improving the circuit layout.

Areas of Agreement / Disagreement

Participants generally disagree on the correctness of the circuit wiring and the implications of using a single rail power supply. Multiple competing views on the circuit configuration and power supply connections remain unresolved.

Contextual Notes

There are limitations regarding the assumptions made about the circuit design, the specific configurations of the components, and the implications of using different power supply setups. Some mathematical and technical details remain unresolved.

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no you did not wire it correctly, you might also want to put a 22pf cap across r2 to stop high freq oscillations .
 

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Short answer? No.
 
Does it have to do with both legs of the 9.1k Ohm resistor being on the same node? I moved one of the legs to the output node.
 
Bystander said:
Short answer? No.
better?
 
You're terrifying me with the use of power supply rails for input and output.
 
Bystander said:
You're terrifying me with the use of power supply rails for input and output.

What would be a better option for input? Is my resistance configuration right atleast?
 
You're missing a common connection for the two power supply rails. The 1k end of the voltage divider needs to be connected to that common.
 
Very quick note regarding power for the op-amp: you will generally (not always) be looking for three connections, 1) a positive voltage (+15, or 9 for a 741); 2) a negative voltage (-15); and, 3) a common, ground plane, source reference tying the low end of the positive, and the high end of the negative supply sources together. i.e., two nine volt batteries in series, the positive terminal of one being the positive source, and the negative terminal of the other the negative source, and the connection between the two being the common, ground, reference plane for the circuit.
 
  • #10
baller2353 said:

closer but still several wiring probs ... am going to try and modify your pic
be back soon

Bystander ... the 741 will operate from a single rail PSU :)
 
  • #11
davenn said:
the 741 will operate from a single rail PSU :)
Been a few years. I'll leave this to you --- you're obviously more "current" on the topic.
 
  • #12
with a single rail you just cannot obtain full swing from 0V to VCC miss by a couple of volts at each end ...OK here's a quick (rough) drawing on the same board you used ... don't have a BB with me to do an actual construction and photo

opamp1.JPG


for power rails its always good practice to use the + line on one side and the - line on the other side of the board

you can see there are only 2 jumpers ... 1 from pin 4 to 0V rail and 1 from pin 7 to +V rail

the 2 wires going off the bottom of the board from pins 3 and 6 are input and output respectively
you can see the wiring is much less complicated :)

Dave
 
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  • #13
davenn said:
with a single rail you just cannot obtain full swing from 0V to VCC miss by a couple of volts at each end ...
No different than split supply. The 741 is not a rail to rail op-amp. Makes no difference where the reference is that we call 'ground'.
 

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