FOC-Stim: a new approach to DIY stim hardware.

[ridgeracer]

So I have a question.
I'm using a BT stereo box now.
Is this FOC compatible with all mp3 stim files or do you have to download an app for it to work? And will I benefit building and trying this style box? What would the benefits be?

Ok got it.

[Pinco]

hi,
other users of FOC states "it feels much smoother than traditional stereo stim" so I guess there is something wrong in my implementation, same trodes and placement and I get very unpleasant stingy playing.
I checked the wiring and the component list and everything seems ok.
Any suggestion?

component list from Mouser
B-G431B-ESC1
42TU400-RC Xicon XFMR 500CT-8CT /
SBCP-11HY221H KEMET 220uH 10% 0.95A
FG18X5R1E106MRT06 TDK RAD 25V 10uF X5R 20% /

[Pinco]

this is the teleplot output without connections

[Pinco]

hi,
other users of FOC states "it feels much smoother than traditional stereo stim" so I guess there is something wrong in my implementation, same trodes and placement and I get very unpleasant stingy playing.
I checked the wiring and the component list and everything seems ok.
Any suggestion?

Solved, it was a cold junction... I can confirm that "it feels much smoother than traditional stereo stim" I tested on ROD but for best results I had to change my usual trodes placement from C -Head L-base of shaft R-Perineum -> C-base of shaft L-head R-Perineum

[splentis]

It is normal that the current limit triggers when the outputs are not connected. The software only works correctly when the electrode resistance is below 1500ohm. I should implement a different error that complains the electrode resistance is too high, rather than the current limit.

Can you send me a log with the electrodes connected? Then I can diagnose the problem.

After thoroughly testing everything with a multimeter, I believe one of my cable connections was bad. Since soldering up a replacement everything has been working perfectly!

[rob1112]

I have bought everything off diglet's parts list but have now realised it's just going to be a mess of wires sitting on my desk!

I'm pretty sure I can put this together but I'm not a regular electronics tinkerer - the thing I could really do with help with is a case to assemble this all in. I know some of you have 3d printed one - would anyone in the UK care to print and sell me a case please? Or perhaps share the STL so that I can get it printed locally? Or is there a generic style of case that would work well that I could pick up?

Final question: Is this the place to ask? I feel like there should be another forum somewhere where this is being discussed with many more hobbyists able to contribute.
TIA

Edit: Sorry just realised that edger open sourced his case. (thank you). Now just need to find someone to print me one https://github.com/edger477/FOC-Stim/tree/master/case

[f12345u]

You can check out Joannes E-Stim Community on discord. Active development of this occurs there.

[darthjj]

Finally got around to test driving my FOC-stim (the different parts are still taped to a board and not properly mounted in a box :S) and it feels really nice, but difficult to say if really different from stereostim with pulsed Restim so far. Playing around with different volumes, the linear intensity feels much more responsive than the stereostim, and I think smaller nuances are more noticeable. However, I can barely feel anything with "volume" less than 50% in Restim (pot in middle, already at 90% volume it feels very intense).

Teleplot appears to stop working when Restim is running for me.. Though perhaps it's some permission issue, will have to look into it.

The V3 looks really cool, will you be selling PCBs with all the tiny components presoldered? If so, what's the estimated price estimate? Hundreds of euros/dollars? Will it be usable as 2ch as well as tri/quad-phase?

[diglet]

Restim sends the data to teleplot with UDP, it should only work if restim is running. Don't open the serial port in teleplot

V3 will support 3-phase and 4-phase operation. 2+2 can be emulated in software (channels not isolated), but I'm not sure if/when that will be implemented because it requires quite some work on the user interface.

Total price price to get the boards assembled and through-hole components delivered to my door is around $/€50 per board, battery not included.

[darthjj]

Ah, that was the mistake then, I was using serial connection..

Perhaps it would be easier to use a box as single channel, and maybe it could be possible to stream mp3 audio for "legacy" stim tracks.

That sounds like a very reasonable const. I assume you'd like some compensation for all the work you put into the creation of the board, and there is of course nothing wrong with that, you probably could sell them with quite a bit of markup judging by what other e-stim devices cost, but if you decide price them on the lower end something like 100-120 each + shipping it would make them quite affordable, and even a multi-device setup wouldn't end up breaking the bank :)

[Pinco]

Hi diglet,
sometimes skipping forward/backward the video (I'm using VLC) the FOC box gives an "Exceeded Maximum Current Error" and stops. The box must be reconnected to the USB port to work again. Is this normal ?
During the playback with FOC pot volume at 60-70% and SW volume at 100% on time to time I hear a buzzing noise from the box that seems a kind of saturation noise coming from transformers/inductors. Is this possible?
Thanks

[edger477]

Hi diglet,
sometimes skipping forward/backward the video (I'm using VLC) the FOC box gives an "Exceeded Maximum Current Error" and stops. The box must be reconnected to the USB port to work again. Is this normal ?
During the playback with FOC pot volume at 60-70% and SW volume at 100% on time to time I hear a buzzing noise from the box that seems a kind of saturation noise coming from transformers/inductors. Is this possible?
Thanks

For me that happens if I disconnect an electrode. Maybe your electrode setup is already running close to limit (high resistance) so even moving to different point in script triggers protection. You could also check if you have latest foc firmware (as I remember diglet raised limits recently)

[diglet]

Hi diglet,
sometimes skipping forward/backward the video (I'm using VLC) the FOC box gives an "Exceeded Maximum Current Error" and stops. The box must be reconnected to the USB port to work again. Is this normal ?
During the playback with FOC pot volume at 60-70% and SW volume at 100% on time to time I hear a buzzing noise from the box that seems a kind of saturation noise coming from transformers/inductors. Is this possible?
Thanks

Not normal. Can you send me the logs, I might need to tweak the limits a bit more.

Some inductors/transformers tick, even when not near saturation. There's not much you can do about it except choosing different inductors.

[BurritoZz]

I've built a box a few weeks back, and it's great! It's my first estim device and so far I'm loving it.
The only issue I notice is that there seems to be a delay between what happens in restim and the outputs.
For example, if I move the current from one pole to another, the device will respond after a delay of about half a second to a second.
This isn't a big issue for the stimulation itself, but has the unfortunate effect of desyncing all synchronised playback.

I can't find a sample rate/delay option in the settings of restim.
Is there some software setting I should change somewhere or ould this be a physical defect in one of my connections?
I am running Linux on my pc, if that is of any relevance.

[diglet]

That is odd, the latency between clicking in the UI and feeling the signal change should be less than 50ms.

There is a latency setting, but it only affects the display update.

Are you using funscript control, then maybe you are dealing with poorly synced funscripts. Although the syncing code in restim certainly is not perfect, it should not persistently be 500-1000ms behind.