Pinco wrote: Thu Feb 13, 2025 2:42 pm
Hi, just started to work on this, I got the firmware built and updated.
It looks like it connects restim but the LEDs do nothing
Is there a way to check if the board is working without connecting coils, transformers, 12v power supply etc?
Not really, the software doesn't do much without connecting 12v.
lorada wrote: Sat Feb 08, 2025 11:48 pm
Just attempted my first build, and it didn't go well. I printed edger477's case, and it was too small to fit the ESC board. I must have screwed up the scaling somewhere.
I assembled everything via breadboard, and got the firmware built and updated. I was even getting data in teleplot, but I couldn't feel any output at all. I was trying to calibrate with the circle pattern in Restim, but I got no sensation through the electrodes.
Any tips on how to begin troubleshooting?
Sorry for the delay I missed your comment.
You can try to short all the outputs and observe the values R_neutral/left/right in the console, this is the estimated resistance of the circuit. These should go down to 0.8 or 1.0 when you play a signal.
If you leave all outputs open, the estimated resistance should go to 15 (the maximum).
Make sure the pot isn't set to 0.
I finally got around to a second attempt with everything soldered properly. The R_neutral/left/right stay at 15, even when I play a signal. I'm not sure what you mean by shorting the outputs. Just connect the leads? The pot is set to 1.
lorada wrote: Thu Feb 27, 2025 5:58 pm
I finally got around to a second attempt with everything soldered properly. The R_neutral/left/right stay at 15, even when I play a signal. I'm not sure what you mean by shorting the outputs. Just connect the leads? The pot is set to 1.
Yes, connect all the leads together (at low volume), the R_ values should decrease.
If they stay at 15, it suggests there is no circuit (soldering mistake) or the transformer is connected in reverse (the side marked P should be the output).
I finished building a FOC-Stim yesterday, and I'm really impressed. Thanks to Diglet for sharing this creation and the excellent Restim app with the community! As others have mentioned, it feels much smoother than traditional stereo stim, is a fraction of the size and cost, and is nearly silent (unlike my DIY stereo stim, which sometimes emits a high-pitched coil whine).
I'm using the 42TU400-RC transformers, SBCP-11HY221H inductors, and FG18X5R1E106MRT06 caps from the recommended BOM, powered by a 12V 2A DC PSU. With the onboard pot wide open (CW), I'm controlling the volume through Restim. I’ve only tested it once, but at 100% volume, it feels comparable to about 80% on my DIY stereo box in terms of intensity. Does that sound about right? Is there anything I can do to increase the power by around 10%? I think that would be the perfect sweet spot.
splentis wrote: Fri Feb 28, 2025 9:31 am
I finished building a FOC-Stim yesterday, and I'm really impressed. Thanks to Diglet for sharing this creation and the excellent Restim app with the community! As others have mentioned, it feels much smoother than traditional stereo stim, is a fraction of the size and cost, and is nearly silent (unlike my DIY stereo stim, which sometimes emits a high-pitched coil whine).
I'm using the 42TU400-RC transformers, SBCP-11HY221H inductors, and FG18X5R1E106MRT06 caps from the recommended BOM, powered by a 12V 2A DC PSU. With the onboard pot wide open (CW), I'm controlling the volume through Restim. I’ve only tested it once, but at 100% volume, it feels comparable to about 80% on my DIY stereo box in terms of intensity. Does that sound about right? Is there anything I can do to increase the power by around 10%? I think that would be the perfect sweet spot.
splentis wrote: Fri Feb 28, 2025 9:31 am
I finished building a FOC-Stim yesterday, and I'm really impressed. Thanks to Diglet for sharing this creation and the excellent Restim app with the community! As others have mentioned, it feels much smoother than traditional stereo stim, is a fraction of the size and cost, and is nearly silent (unlike my DIY stereo stim, which sometimes emits a high-pitched coil whine).
I'm using the 42TU400-RC transformers, SBCP-11HY221H inductors, and FG18X5R1E106MRT06 caps from the recommended BOM, powered by a 12V 2A DC PSU. With the onboard pot wide open (CW), I'm controlling the volume through Restim. I’ve only tested it once, but at 100% volume, it feels comparable to about 80% on my DIY stereo box in terms of intensity. Does that sound about right? Is there anything I can do to increase the power by around 10%? I think that would be the perfect sweet spot.
Thanks for the feedback. I've been seeing more people hitting the current limits, I think I made the limits a bit too low for some electrode placement and/or bad boards.
I increased the current limit margin from 0.2A to 0.3A, reduced the minimum resistance from 0.8 to 0.7, and also expanded vbus and temperature limits. Let me know if you encounter more issues.
This worked, I haven't had any issues since. Thank you!
Hi, I finished building it and I'd like to test before connecting to my body...
In previous posts you suggested
You can try to short all the outputs and observe the values R_neutral/left/right in the console, this is the estimated resistance of the circuit. These should go down to 0.8 or 1.0 when you play a signal.
If you leave all outputs open, the estimated resistance should go to 15 (the maximum).
Make sure the pot isn't set to 0
Yes, connect all the leads together (at low volume), the R_ values should decrease.
If they stay at 15, it suggests there is no circuit (soldering mistake) or the transformer is connected in reverse (the side marked P should be the output)
What is the console you mention? How can I enable it and look for the values ?
Pinco wrote: Sat Mar 15, 2025 9:41 am
Hi, I finished building it and I'd like to test before connecting to my body...
In previous posts you suggested
You can try to short all the outputs and observe the values R_neutral/left/right in the console, this is the estimated resistance of the circuit. These should go down to 0.8 or 1.0 when you play a signal.
If you leave all outputs open, the estimated resistance should go to 15 (the maximum).
Make sure the pot isn't set to 0
Yes, connect all the leads together (at low volume), the R_ values should decrease.
If they stay at 15, it suggests there is no circuit (soldering mistake) or the transformer is connected in reverse (the side marked P should be the output)
What is the console you mention? How can I enable it and look for the values ?
Thanks
this is probably referring to the teleplot instance you can have running to monitor the board.
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?
The FOC-Stim cannot play audio files, it can only play funscripts with Restim. It is possible to implement (some form of) audio playback, but don't expect this soon.
The main advantage of the FOC is current control. Meaning that minor changes in skin contact, skin moisture, body positioning no longer results in a large change in intensity.
diglet wrote: Sat Mar 15, 2025 7:08 pm
Yes. I don't know why I said console, I meant teleplot.
Ok, I got it working now and I see all the waveform in teleplot.
I did a quick real life test with the same trodes and placement but so far I am not getting the right calibration (TBH neither on DIY box is perfect ). BTW I read many times the procedure for it, at which volume carrier frequency etc are you calibrating?
splentis wrote: Fri Feb 28, 2025 9:31 am
I finished building a FOC-Stim yesterday, and I'm really impressed. Thanks to Diglet for sharing this creation and the excellent Restim app with the community! As others have mentioned, it feels much smoother than traditional stereo stim, is a fraction of the size and cost, and is nearly silent (unlike my DIY stereo stim, which sometimes emits a high-pitched coil whine).
I'm using the 42TU400-RC transformers, SBCP-11HY221H inductors, and FG18X5R1E106MRT06 caps from the recommended BOM, powered by a 12V 2A DC PSU. With the onboard pot wide open (CW), I'm controlling the volume through Restim. I’ve only tested it once, but at 100% volume, it feels comparable to about 80% on my DIY stereo box in terms of intensity. Does that sound about right? Is there anything I can do to increase the power by around 10%? I think that would be the perfect sweet spot.
// current limits
#define TCODE_MAX_CURRENT 1.2f // in amps
This can be changed to increase the maximum power output. The maximum is limited by the saturation current of your inductors, which is about 2A.
If you still don't reach the desired power output, the power may be limited by the input voltage or transformer size, but try this first
Fantastic, thank you Diglet I've bumped this up to 1.4f which I think will be more than enough.
I'm running into a current limit exceeded error whenever the volume reaches 90-100%. This is using default settings, uploaded straight from github. If I bump the TCODE_MAX_CURRENT up to 1.4f I get the same error just at a lower volume, >74% ish. Have I reached the limitations of the hardware I've used in my build or is there something else at work here?
The spoiler below is the error message output from Restim. This example is without any electrodes connected and happens within a few seconds from a "cold start" going to 100% volume in Restim. I'll get the same thing with electrodes connected, give or take a few % in volume.
I t seems to function just fine sub 85% volume using the default settings but I'm hoping to see a little more if at all possible?
diglet wrote: Sat Mar 15, 2025 7:08 pm
Yes. I don't know why I said console, I meant teleplot.
Ok, I got it working now and I see all the waveform in teleplot.
I did a quick real life test with the same trodes and placement but so far I am not getting the right calibration (TBH neither on DIY box is perfect ). BTW I read many times the procedure for it, at which volume carrier frequency etc are you calibrating?
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.
I've bumped this up to 1.4f which I think will be more than enough.