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

[edger477]

Would anyone be willing to post a step-step build of their FOC unit? It would be great if they could.

Thanks.

I second that. This tech sounds absolutely fantastic. I understand that this might just not be intended to be built by someone like me and if so, carry on gents, but I honestly don't feel like the layman has enough information to work with given the risks involved with these kinds of devices. The BOMs I've seen are a little confusing and while diagrams mean everything to most people in this thread, I have no clue how to actually put one of these together only from looking at that or a few pictures of the finished product.

I put few pics of how I made mine (along with cad files for 3d printed case and bom of all that I used to make them) to the fork of the repo https://github.com/edger477/FOC-Stim/tree/master/case

[UFungus]

I put few pics of how I made mine (along with cad files for 3d printed case and bom of all that I used to make them) to the fork of the repo https://github.com/edger477/FOC-Stim/tree/master/case

This is indeed very helpful! I didn’t realize at first that the protoboard was located under the ESC, which explains why it’s so compact. I’ve already found most of the components from the original BOM, combined with the ones you provided. I also have a 3D printer, so thank you very much for sharing those files. While I’d still feel more confident with some sort of guide, I think I now have enough understanding to start ordering the parts to make a couple of these—or at least give it a try. I was pleasantly surprised at how much easier it is to find most of the parts here in Canada, especially compared to the hassle of sourcing transformers for my other boxes.

[edger477]

I’d still feel more confident with some sort of guide

I don't feel it is possible to make a guide where I would guarantee you solder everything properly.

You need to be able to identify transformer, inductor and capacitor on schematics and think about how each of the 3 outputs is connected (input through inductor to one side of transformer).

Make sure you solder one side of transformer outputs together(to same piece of wire, that has nothing else connected), and do the same with middle inputs of transformers (another piece of wire that doesn't have anything else connected). Do the same with one side of capacitors.

That leaves you with 3 free capacitor terminals that need to be connected to the input terminal of transformer that you will use, and connect each of them to one leg of inductor, because other leg of inductor is input from the board (so each of the 3 transformers inputs has both one of capacitors connected and one of inductors)

You can go through steps above in your mind, placing the components and looking where you will solder things, then actually do it backwards, the last step first (since you can plug in inductor and capacitor so that one of their legs are near the input of transformer so you don't need wire for that, make terminals touch each other and solder them). You can look at my pics of protoboard to see how I organized components, I found that layout is close to optimal, but make sure you place inductors with transformers (it is hard to push them inbetween after you soldered transformers), and to have tweezers if you will add capacitor later.

[diglet]

I recently completed by box, see below.



I use a solderless breadboard because I swap components every other day to test stuff, everyone else should just solder

The hardest part is mounting the board, I figured clamping the USB port was the best approach for my box.

[UFungus]

You can go through steps above in your mind, placing the components and looking where you will solder things, then actually do it backwards, the last step first (since you can plug in inductor and capacitor so that one of their legs are near the input of transformer so you don't need wire for that, make terminals touch each other and solder them). You can look at my pics of protoboard to see how I organized components, I found that layout is close to optimal, but make sure you place inductors with transformers (it is hard to push them inbetween after you soldered transformers), and to have tweezers if you will add capacitor later.

With the description you just posted and the picture @Diglet just posted(thanks you very much for that). It just got a lot more "digestible" and I feel like I can definitely piece it together now. Having the parts in hand will certainly help me more with processing what goes where. Thank you all for helping out. I'll report back if I need help/when it's completed!

[darthjj]

The hardest part is mounting the board, I figured clamping the USB port was the best approach for my box.

My stereostim box doesn't have any exposed circuit boards, but I used double sided tape to attach the metal plate which I bolted the transformers and resistors to. Not as good as a proper 3d printed bracket, but appears to work as a quick and easy semi-permanent solution.

[JakofClubs]

Finally, a modern DIY design! A major benefit of FOC-Stim is that it's less numbing that stereo-stim, IMHO. It manages to deliver a strong signal without the painfulness that stereo-stim sometimes has. It runs off a 12v 1A power supply, which is much more common than the typical 12v 5A ps.

[darthjj]

Finally, a modern DIY design! A major benefit of FOC-Stim is that it's less numbing that stereo-stim, IMHO. It manages to deliver a strong signal without the painfulness that stereo-stim sometimes has. It runs off a 12v 1A power supply, which is much more common than the typical 12v 5A ps.

Isn't that because it uses a pulsed signal, and you'd get the same experience with a stereostim box if using the same type of signal instead of a continuous sine wave?

Spent two days soldering the FOC-stim and figuring out the hardware (platform.io is pretty easy, but stm32cubeprog wasn't quite user friendly), now I only have to design and print a box to put it in before I can test it myself.

Found a couple of old NUC PSUs which deliver 19V to the same type of barrel connector that I have. Ought to work fine if the onboard voltage regulator is made for 6S LiPo packs I think.

[diglet]

I don't expect differences in numbing between FOC-Stim and stereostim with Restim in pulse-based mode. The waveforms generation is exactly the same, the only real difference is the current control. I plan to experiment with new types of waveforms at some point.

19v will work. You will have to change the voltage in src/config.h (STIM_PSU_VOLTAGE). Be extra careful that the 19v wires are nowhere near the wires that go to your body.

[JakofClubs]

I don't expect differences in numbing between FOC-Stim and stereostim with Restim in pulse-based mode.

Perhaps I misatribute the difference to FOC-stim when that improvement was Restim.

[throwawayacct]

I'm not sure if folks remember SmartStim website and some of the nuances that functionally gatekept e-stim from a whole lot of people.

Back in the dark ages, the only real, cohesive resource for e-stim was a web forum called SmartStim. It was a "free" site, but if you wanted any access to mp3/wav files people had made or collected from prior composers like Claude or Joan Vixen, you had to pay the site admin. Even so, you could only get maybe 20 or so files that had been published because....

They developed a custom software for e-stim tone and file generation. But it only ran on PC. It was called, not surprisingly SmartStim and went through 4 incarnations before the site admin had health issues and a significant fracture occurred in the E-Stim world around the same time. The admin passed away, and the site/software only lives on in memory and a few people who saved versions. From what I can gather, there were hundreds of files in the ss4 format, which are now either gone, or totally unusable by anyone who doesn't have this ~12 year old software and a Windows machine that can run it.

The big split was significant in that the SmartStim admin was very much opposed to any stim devices that were not built to their exact specs, or ET-312. They actively removed posts about other builds, other brands, and one builder/DIYer decided enough was enough and started Social Stim and sold a handful of BT-Stim models.

What is my point?

Restim sounds pretty great. Too bad I have a Mac, and cannot (because work machine) go partitioning it off, and I'm a ways off from affording a new machine that isn't crammed with 20 years of my business. I'm not a developer or programmer, and when coding is needed by the end user to run something on the mac, it's not going to happen on my work machine - I cannot take the risk of messing something up.. I know I am not alone in this.

Effectively all these emerging updates to E-stim are gatekept away from people who don't have a PC. The addition of this new device that runs directly off Restim is also functionally walled off from everyone who does not have a PC. It sounds like there is a notable safety upgrade in this new device, and half the community cannot use it.

We're circling back around to the shitty days. I've been a stimmer for a long time, I've made a bunch of files for people to enjoy and a bunch of video, I've been an active part of the e-stim community for 15 years across several forums. So this is not a beg from a rando who hasn't contributed.

And those years where we all had accessibility, could easily share mp3/wav, and really, really grew e-stimming as a kinky fun time for a lot more people... Those were pretty great. A development of a new device or new software should be something that helps this along. But it's walled off from 1/3-half of the folks using e-stim.

Please, Diglet, edger... someone who has the skills, develop a port or shell or whatever the hell it's called, for OSX. Doing so is well out of my own wheelhouse, as are all the hoops to set it up on Mac, safely. If I could, I would have done it myself right after Restim launched.

[edger477]

Please, Diglet, edger... someone who has the skills, develop a port or shell or whatever the hell it's called, for OSX. Doing so is well out of my own wheelhouse, as are all the hoops to set it up on Mac, safely. If I could, I would have done it myself right after Restim launched.

Until I read this, I was about to write "So developers should buy mac to develop software because you walled yourself off from majority of computer users? Because you are too lazy to run python on mac?"

But obviously you formed your opinion without all the facts. You can run python on mac just fine and there is even release that people ran on mac: https://github.com/diglet48/restim/acti ... 2668927317

Of course you will have to mark the executable as executable yourself because developer only can do that if they pay Apple for certificate, which of course author of free software who doesn't use mac will not do.

I have also published OSX build for the restim-controller software I wrote, no one is trying to wall off anyone, and everything here is open source.

[diglet]

I'm sorry but I can't help you further. The software is open source and cross-platform (windows, linux, mac), many people are running it on their linux or mac machine.

The only thing that is missing is a proper release package so people on various mac machines can run it without using the command line. Unfortunately apple walls me from creating/testing a proper release package on mac unless I buy their hardware and give up my anonymity.

[JakofClubs]

throwawayacct,
I was on SmartStim back in the day. Their level of gatekeeping was a whole different thing. They wouldn't even allow links to mp3's or other sites because of "copyright concerns".

I'm primarily a Linux user and a full time Linux admin, but I bought a used $200 Dell Precision Windows PC off Ebay for estim because I don't feel like fighting it and not everything I want to play with has a Linux version. I recommend taking the path of least resistance in things like this. Do yourself a favor and get a Windows PC if you don't want to mess with your work Mac.

[edger477]

I was on SmartStim back in the day. Their level of gatekeeping was a whole different thing. They wouldn't even allow links to mp3's or other sites because of "copyright concerns".

Yeah I was there too... Mentioning that site in this context made me smile for real because that strawman is so ridiculous.