Hand drawing schematics, and TinkerCad schematics are presented below. Did I assemble the circuit correctly? I am trying to have my drawing laid out first prior to physically assembling. The first opAMp is actually INA128 which is instrumentation amplifier.
I've not checked everything but the-ve of your top battery is not connected to anything on the breadboard, it should be connected to ground.
Your right hand opamp has no connection to pin 3.
I made some edits
You now have no ground on the breadboard.
I think you are overthinking your approach.
- print out your schematic (or have some hard copy)
- Define what strips of your solderless breadboard will be +V, -V and Ground.
- If you have enough wire colors assign a color to +V, -V, Ground and signal.
- Go through each connection one by one and verify its connection and highlight it on the schematic as done Including connections to ground.
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Did you trace each connection to the schematic? I sound like a teacher, which I am not.
To build and trouble shoot this project you will need a multimeter. Even a cheap one will do.
General comments:
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You have not capacitors across power to the ICs. In reality you will need a 0.1µF at each +v to ground and each -V to ground. They must be very close to the IC they are protecting.
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You need to have a plan to troubleshoot. The function seems to be AC related with some gain and filtering. How do you test it to verify function?
Just out of curiosity: what's the intended behavior of this circuit? I see a presumably high impedance AC signal being amplified 8 times or so, then run through what looks like a lower impedance inverting buffer, followed by another but higher impedance inverting buffer. Or did I miss anything?
What's the purpose of both 741's here? Wouldn't just an INA129 be capable of driving an Arduino ADC pin directly?
simulate EKG
I am trying to ensure the connections are right in accordance with the schematics. However, I have not assembled it or tested with the multimeter yet. Yes, I have traced the schematics and this my setup. Surely, I have to make sure the resistors and capacitors are the same as in the schematics, but the current wiring within the diagram are generic
Ok, is it supposed to oscillate or something? I see you have a 'Vout' going into the inverting pin of the INA128 and the same net label on the output of the second LM741 (with a cap in-between). I don't see that connection on your breadboard.
More correctly, perform an ECG.
Safety considerations dictate that you should at least have 1M series resistors in the arm leads. And the same resistor in series with the leg lead to ground.
Actual ECG systems use "active" shielding on the leads.
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