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

AI Thread Summary
The circuit built on the breadboard using the LM741CN op-amp has several wiring issues, including a lack of a common connection for the power supply rails. A 22pF capacitor across R2 is recommended to prevent high-frequency oscillations. The configuration of the resistors needs adjustment, particularly ensuring the voltage divider connects to the common ground. The LM741 can operate on a single rail power supply, but it will not achieve full output swing from 0V to VCC. Proper wiring practices, such as separating positive and negative power lines, are essential for optimal circuit performance.
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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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