HACK_GVS

Today I cleaned up the schematic by organizing it into more readable sections. I updated the op-amp power inputs to use ±15 V supplies and added a DAC input (0.0 V to 3.3 V). While routing, I realized I had forgotten to connect the ground for the dual ±15 V power input, so I corrected that. I also added a dedicated 3.3 V input from the microcontroller to feed the op-amp buffer, providing a lower impedance reference voltage.
also the routing was a breeze as there werent many components, so after arranging the components, i routed them and made the silkscreen much more organized and added power labels for easier use!
so my work is done for now i might try to add my own doodles on the pcb i have the time, i now need to complete my repo and BOM

okay so for today i decided to simulate my circuit in ltspice, i wanted to know about two things:

• a well prepped mastoid electrodes, has an impedance of 2k ohm, but this range can go to well above 10s of thousands of ohms, if skin in not well prepped or not prepared. i wanted to find out how much current my circuit would be able to deliver in these different conditions, i also wanted to know what would happen if there was no resistance
• what supply voltage should i use for my opamps, as if i choose too low the current would sag under load and wouldnt be able to deliver the necessary current

findings:
-so i started simulating by circuit with +- 12v as the power supply here are the results :
-0.1 ohm = 2.999mA
-2k ohm = 2.999mA
-3k ohm = 2.54mA
-5k ohm = 1.72mA
-7k ohm = 1.28mA
-10k ohm = 930 µA

• after that i decided to increase my supply voltage to -+15v for more head room,im too lazy to type all the values out right now but here are the top 4:
  -0.1 ohm = 2.99mA
  -2k ohm = 2.99mA
  -3k ohm = 2.99mA
  • 5k ohm = 2.21mA

so as you can see the later one performed much better, i simulated +-24v too which gave me really good results, since tl082 has only a max supply voltage of +-18v, so im going to operate it wtih +-15v

hello there!, so im making a pcb called HACK_GVS , which will essentially be able to control human balance!!! isnt that crazy??

• So to understand how we will do that we need to know about GVS (galvanic vestibular stimulation), inshort when you apply a controlled amount of current (0-3mA) to your mastiods, itll stimulate your vestibular system, and your brain will think your head is not aligned with your body so in order to compensate your body will lean on one side, and if you reverse the current the opposite will happen

-so how will we design this?

• we basically the pcb will be sectioned into two main parts, a unity buffer which will output low impedance 1.65v, and an opamp in non inverting configuration which will act as the solver

-why do we need the solver?
-so the mastoids will have a variable resistance due different positions of electrodes each time, sweat, oils, humidity,etc but we need to put a constant current through our mastoids, that’s why we need a solver that will calculate the voltage based on skin’s resistance and supply constant current!