Hello,
I would like to make a DIY EEG version with Arduino, the original diagram can be found under the link, I also made one acording to one on the website and I want to make a PCB from it, so my question is: Is my electronic schematic fine? or are there any bad connections etc.?
Regards
Look carefully at the capacitors with respect to:
How are you powering the Arduino ?
Can't see any decoupling capacitors....
I'd label the virtual ground as such to avoid confusion with the negative rail.
Add a schottky from the output to ground (after the 10k) to stop it trying to drive negative voltages into the
Arduino pin? (Yes, the 10k does protect, but adding the diode makes it properly robust and furthermore
is clear that negative signals are not allowed there, again making it more readable.
And please use circuit symbols, not package outlines, for drawing circuits, its so much more readable.
Thank you!
I recreated schematic with proper symbols, added protection diode before arduino.
Something else?, overall does this circuit has chance to work propperly? ?
Regards
MarkT:
Add a schottky from the output to ground (after the 10k) to stop it trying to drive negative voltages into the
Arduino pin?
I don't see how U2 could output a negative voltage, after all it doesn't have a negative power supply.
avik111:
I recreated schematic with proper symbols.
That's a lot more readable indeed! Not to say simply the second is readable. The first, not so much.
Something else?, overall does this circuit has chance to work propperly? ?
I don't see any major issues. So get out your breadboard and start building, see what it does!
1 uF caps are larger than usual for decoupling but that shouldn't be an issue. Just curious, any reason to choose the CA3130 over a dual OpAmp part? Saves on part count.
1 uF caps are larger than usual for decoupling but that shouldn't be an issue. Just curious, any reason to choose the CA3130 over a dual OpAmp part? Saves on part count.
I will use dual OpAmp and 100nF decoupling capacitors for sure.
I don't see how U2 could output a negative voltage, after all it doesn't have a negative power supply.
Author of original schematic:
The amplifiers require a neutral reference, or floating ground, halfway between the Arduino’s 5V positive and ground supplies. The second 3130 (farthest to the right in the photo, with the two 15K resistors) provides this. Wire it up, plug in the Arduino (I assume you will be powering it from the USB cable), and check with the voltmeter to be sure that the 3130 is putting out 2.5 volts at pin 6. This output will be “neutral” for the other two chips.
Regards
That still doesn't make, or even allow for, any voltage coming out of that OpAmp U2 to drop below 0V (the actual ground).
Okay, that's right - my bad. Can I use for example circuit based on 555 timer like one below?
If not, what is the simplest sircuit that will meet the requirements?
Regards
What requirements? You're quickly losing me here.
wvmarle:
I don't see how U2 could output a negative voltage, after all it doesn't have a negative power supply.
With the clearer schematic that's a lot more obvious!
i want to make circuit EEG, and i search for person already did this project, for give me the advices and more info about this,
thank you
my contact mail :elkassah96@gmail.com
whtp:+212625986235
best regards
reda
