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kitschpatrol
signal strength
I've got the mindflex 2 wired to arduino uno , but the signal strength never reached the zero and always the attention and meditation values are zeros, that's when i have the headset on my head, the lowest value reached for the signal strength was 26, any idea what's wrong?
Did you try using conductive gel or paste for electrodes ? I tried this with good results in the same situation.
Which electrodes you mean ( mindflex Tx & GND ) and how exactly? On 2 Jan 2015 10:01, "Couby" [email protected] wrote:
Did you try using conductive gel or paste for electrodes ? I tried this with good results in the same situation.
— Reply to this email directly or view it on GitHub https://github.com/kitschpatrol/Brain/issues/12#issuecomment-68512749.
The electrodes are the metal knobs on the headband. You can just put the gel between the electrodes and the skin. Alternatively, saline solution also helps, but not for long. Ultrasonic gel might be a cheap alternative. I also like to use adhesive disposable electrodes sometimes. They give also better results than the cheap electrodes integrated in the headband. For long-term use you might want to think about silver electrodes as a replacement of the integrated ones. Self-made ones from conductive silver fabric are quite comfortable to wear.
@cslinux I use it on both.
@steeph-k
Self-made ones from conductive silver fabric are quite comfortable to wear.
Do you have any recipe or build log about such self-made electrodes ? Sounds cool :-)
Oh, I guess I misunderstood the question about which electrodes. Is it called Tx sometimes?
There is this guide to make replacement sensors for the discontinued Zeo headband. I think it should give a good idea how to make a similar headband.
I didn't make one myself (so far). But I have used a headband made after this guide and it was great! :)
If you can attach a picture showing these electrodes i'll really appreciate it as well can i use paste on them? On 2 Jan 2015 14:44, "steeph-k" [email protected] wrote:
The electrodes are the metal knobs on the headband. You can just put the gel between the electrodes and the skin. Alternatively, saline solution also helps, but not for long. Ultrasonic gel might be a cheap alternative. I also like to use adhesive disposable electrodes sometimes. They give also better results than the cheap electrodes integrated in the headband. For long-term use you might want to think about silver electrodes as a replacement of the integrated ones. Self-made ones from conductive silver fabric are quite comfortable to wear.
— Reply to this email directly or view it on GitHub https://github.com/kitschpatrol/Brain/issues/12#issuecomment-68524291.
Or maybe I didn't misunderstand you. I only have an old Mindflex. It looks a bit different. And I couldn't find a picture of the new one where the electrodes are visible. There is only one electrode on the forehead. The other two are in the earclip. Depending on what you want to do it would be better to place at least one of the earclip electrodes on the sculp as well. But that's not a matter of signal strength, just a side note.
So what do think ppl? Just i have to use a paste on the ear clip and the forehead electrode?
I don't think that paste would be a good solution. But you don't have to buy gel, either. Have a look at this: http://www.bioshare.info/en/diygel
Actually i've tried with paste and salt/water , always signal strength isn't lower than 26 and always meditation/attention is zeros even on the processing brain graph-er.
Shouldn't meditation and attention still go up sometimes even with a connection value of 26? If connection strength is the issue maybe one of the connections of the wires is damaged. Or maybe your body is very very dry. (Do you happen to be a zombie?) So it doesn't sound anymore like the connection of the electrodes is the source of the problem.
You mean the Tx / GND soldering? On 3 Jan 2015 10:49, "steeph-k" [email protected] wrote:
Shouldn't meditation and attention still go up sometimes even with a connection value of 26? If connection strength is the issue maybe one of the connections of the wires is damaged. Or maybe your body is very very dry. (Do you happen to be a zombie?) So it doesn't sound anymore like the connection of the electrodes is the source of the problem.
— Reply to this email directly or view it on GitHub https://github.com/kitschpatrol/Brain/issues/12#issuecomment-68587910.
Maybe. If they look especially bad, I'd re-solder them. It's not very likely that this is it. But I don't have a better idea.
Basically just adding an optoisolator did the trick for me.
I tried conductive gel, filing the electrodes, resoldering, using a salty solution, all sorts of interference shielding, grounding etc and it didn't work. I even rang up a neuroscientist for tips...
Bought this for a pound and it worked instantly, 90% of the time it doesn't need the gel either. http://www.maplin.co.uk/p/high-voltage-opto-isolator-ay44x So I'm not sure if it's my PC specifically or my Uno, but since you should probably surge-protect your brain anyway, I"d say go for it.
Definitely a good tip. If you don't transmit the signal wirelessly adding an opto-coupler is a good idea. I don't know if it's enough to protect you from a shock if something goes very wrong, but it should improve the signal quality.
As well which of the following you meant ?
http://www.ram-e-shop.com/ds/ic/MOC3063.pdf
http://www.vishay.com/docs/83725/4n25.pdf
steeph-k: Heh, they're actually rated for about 5000v... kinda impressive considering how easy they are to blow out.
cslinux: If I remember right, people have had success with the 4n25. For wiring instructions, I'd suggest maybe finding a youtube example, or checking google images for schematics.
On Sun, Jan 4, 2015 at 1:56 AM, cslinux [email protected] wrote:
As well which of the following you meant ?
http://www.ram-e-shop.com/ds/ic/MOC3063.pdf
http://www.vishay.com/docs/83725/4n25.pdf
— Reply to this email directly or view it on GitHub https://github.com/kitschpatrol/Brain/issues/12#issuecomment-68617515.
sicklebrick: The 4N25 should be wired to the arduino or to the mindflex ??! , sorry for such a question .. :(
sicklebrick: i couldn't find any wiring instructions, as well i don't know if i have to wire it between the arduino and the Mindflex Tx / GND or what ? i.e the inputs should be the mindflex tx and then the optocoupler collector goes to the rx ?
Uhm, you should probably look up some guides for basic electronics for this. The optocoupler is essentially 2 components, each mounted on either side of the 'chip' One's an infrared LED, and the other's a detector.... so flash signal in, and it becomes conductive on the other side. I suppose if you don't really understand you could just try all the pin combinations, lol.
Mindflex TX&RX -> Optocoupler transmitter side -> Opocoupler reciever side -> Arduino TX&RX
But really, practice with an LED or something
On Wed, Jan 7, 2015 at 4:00 PM, cslinux [email protected] wrote:
ppl any comment?!!
— Reply to this email directly or view it on GitHub https://github.com/kitschpatrol/Brain/issues/12#issuecomment-69042603.
Mindflex TX&RX -> Optocoupler transmitter side -> Opocoupler reciever side -> Arduino TX&RX
Shouldn't there be one for Tx and one for Rx?
Nah sorry, I was tired and not thinking straight... you don't use the mindflex's RX at all and don't use the arduno's TX at all. It doesn't transmit anything back along the TX line!
In theory you could do it with an infrared LED and detector at the other side, but that kinda setup won't handle the transmission speed properly... so coupler =)
Also, I found with the second set of couplers I bought that the mindflex was a little short on power, so I used the TX line with a transistor and 4.5v supply on the transmit side... Oh, and a little pull up resistor on the receive side.
Pic: http://i.imgur.com/OtV26Kg.png?1
On Thu, Jan 8, 2015 at 6:26 AM, steeph-k [email protected] wrote:
Mindflex TX&RX -> Optocoupler transmitter side -> Opocoupler reciever side -> Arduino TX&RX
Shouldn't there be one for Tx and one for Rx?
— Reply to this email directly or view it on GitHub https://github.com/kitschpatrol/Brain/issues/12#issuecomment-69141156.
which kind of transistor and how it's connected in details? i see a capacitor and a resistor on the transmit side and a resistor on the receive side.
As well i've this ECG electrode http://store.fut-electronics.com/ecg-electrode/dp/1188 , but not sure if it can help in the signal strength issue and if yes how to connect it to the Mindflex electrodes
To properly connect these electrodes you need a cable like the one suggested by the shop: http://store.fut-electronics.com/ecg-electrode-cable-%283-wires%29/dp/1437
Cut off the jack plug and solder the wires directly to the ThinkGear module.
steeph-k: which ThinkGear module, i'm using Mindflex and it has neurosky module with TX and RX already connecting the Tx to Arduino Rx and GND to GND