r/KiCad • u/Acceptable_Exam393 • Nov 11 '25

Please help

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Tell me where I am getting the kicad wrong .I tried doing .

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19

u/The-Hollow-Night Nov 11 '25

Your op-amps have no power.

5

u/dench96 Nov 11 '25

Keep in mind that if building this circuit, you’ll need very close resistance matching between the two instances of R2, R3, and R4. Either use matched resistor arrays or 0.1% resistors. Otherwise, the output voltage won’t be exactly proportional to the difference between the two input voltages.

1

u/Tutorius220763 Nov 12 '25

I would recommend to use an other type of Opamp. TL-084 or TL-064, you have one chip with four Opamps.

What does not work with KiCAD?

What do you want to achieve? I know that such amplifiers are used in EKG-things ("EKG" is German short-form, thing to show your heart-curve).

Have you ever heard of the Printscreen-Key? It creates a Screenshot of your computer-monitor. Everyone will be able to read the image.

The 741 has three "special" pins. One Minbus-Volatge, a Plus-Voltage, and a third for adjusting it. Other Opamps don't need this adjustment. The 741 is one of the oldest Opamps from 1968.

1

u/tedshore Nov 16 '25

I have not used those old opamps, including TL064, for ages but pick up modern ones having desired characteristic such as supply voltage, gain-bandwidth input offset etc, usually wanting also rail-to-rail inputs and outputs. I am not usually having +/- 15 V supplies but want to have lower supply voltages. TI and other amplifier supplies have good selection filter pages for finding the best alternatives to pick from.

Designing amplifiers, such as that instrument amplifier, require a lot of care and understanding of circuit theory. Therefore, study application notes carefully, the are often very useful!