Low-cost (~$40-60) DIY Stereo E-stim for Audio Input (based on TroniC's MidiStim)

[Electro]

The SMSL amp should be just fine, I have two different estim rigs and one of them uses the same amp and it's more powerful than I can handle when it's cranked to the top.

With that being said, my phone volume is generally set at 90-100% when my laptop might be in the 30's or so. Your phone could have a lower output than even mine.

Also you didn't mention what you are trying to use for estim audio, some is much lower volume compared to other estim. Something like Estim Tower or Estim Mansion is nearly full volume with pain sections generally touching full volume. Some stuff on Milovana is much lower volume, B.E.S.T., Estim Experiment, and Estim Bondage come to mind as being quieter.

[phoopha]

The SMSL amp should be just fine, I have two different estim rigs and one of them uses the same amp and it's more powerful than I can handle when it's cranked to the top.

With that being said, my phone volume is generally set at 90-100% when my laptop might be in the 30's or so. Your phone could have a lower output than even mine.

Also you didn't mention what you are trying to use for estim audio, some is much lower volume compared to other estim. Something like Estim Tower or Estim Mansion is nearly full volume with pain sections generally touching full volume. Some stuff on Milovana is much lower volume, B.E.S.T., Estim Experiment, and Estim Bondage come to mind as being quieter.

I'm using a Galaxy Note 10 phone, just like I would with my 2B, set at max volume. Yesterday, I did a comparison and, on a like-for-like basis, couldn't go higher than 35 on the 2B in stereo mode, map C.

I have tried a number of the estim videos, Estim Tower, and Estim Clinic, all at maximum volume on phone and the amp.

Having listened to the Fosi amp, I don't expect it would feel any more powerful, as to my ears it sounded the same as the SMSL, certainly not the BS 100w per channel they claim. I guess my next step is to try using my laptop as a source and see how that goes, though I'm not feeling too hopeful.

[phoopha]

I have now tried using my laptop as the source. On Estim Tower, there was a definite improvement, still not as powerful as I would have hoped - I could still take the pleasant stim files at max, but the pain files certainly made me jump!

I have had less success with the Estim videos, although Estim Whip and Pain Electro was a bit better, again making me jump a bit. However, a lot of the other videos still lacked much power, certainly far, far less than when used with my 2B.

I even tried the Fosi's 24v power supply with my SMSL amp, but it made no discernable difference.

So, I'm now really unsure about what else I can try!? Granted, I could remove the secondary resistors, and just use the parallel 3r9 25w ones. Maybe a 12 power supply with a higher amperage? Or am I just so,e sort of electro-freak that doesn't really respond as much as others!?

Edit - just a thought, what if I were to try putting the 3r9 on the 'output' side of the transformers?

[InfamousPlantain]

Well,

I don't have much ideas for your situation. Perhaps removing the secondary resistors may simplify the setup so you can go back to the basics of the design just to see what's up.

One other issue I encountered that I didn't go into detail was that my project box itself was conductive. It didn't occur to me that the banana sockets I ran through the holes of the casing were essentially getting shorted out. When I first set everything up, I barely felt anything at all and couldn't figure out what was wrong. I stared at everything without any idea until I broke out the multimeter and started continuity testing. Was surprised when I had continuity between different banana sockets. As it turns out, the sockets I used were cheaper ones that did not insulate themselves as they passed through the holes of the project box. As the holes were slightly larger than the piece that went through them, some sockets were shorting, some were not. Gave all sorts of unpredictable results. Ended up adding heat shrink tubing to that middle part that passes through the hole for all of them and shocked the heck out of my arm the first time after that!

bananasocket - Copy.jpg (40.67 KiB) Viewed 4347 times

If you're willing to post a quick pic of your setup or diagram, someone may spot an issue.

good luck, if you haven't figured it out already.

[phoopha]

Well,

I don't have much ideas for your situation. Perhaps removing the secondary resistors may simplify the setup so you can go back to the basics of the design just to see what's up.

One other issue I encountered that I didn't go into detail was that my project box itself was conductive. It didn't occur to me that the banana sockets I ran through the holes of the casing were essentially getting shorted out. When I first set everything up, I barely felt anything at all and couldn't figure out what was wrong. I stared at everything without any idea until I broke out the multimeter and started continuity testing. Was surprised when I had continuity between different banana sockets. As it turns out, the sockets I used were cheaper ones that did not insulate themselves as they passed through the holes of the project box. As the holes were slightly larger than the piece that went through them, some sockets were shorting, some were not. Gave all sorts of unpredictable results. Ended up adding heat shrink tubing to that middle part that passes through the hole for all of them and shocked the heck out of my arm the first time after that!

bananasocket

If you're willing to post a quick pic of your setup or diagram, someone may spot an issue.

good luck, if you haven't figured it out already.

Hmm... now that's an interesting thought. I have used an old metal biscuit tin. I insulated the inside with duct tape, but I didn't think about the holes where the banana sockets pass through.

As it is, I tried today with a different laptop, plugged in to the mains, and the Fosi amplifier, which uses a 24v power supply, Playing Estim Tower, I was only able to turn the volume on the amp halfway at most, with laptop volume at 100%. It was really intense during the punishment sections.

I shall continue my quest to find what works. I shall also post some pictures of my creation.

[phoopha]

Today, I did yet more arduous testing, all in the name of science!

Same laptop, etc.. as yesterday, with three different teases (the ones on pg3 if you search estim in Webteases). Pow! Just like yesterday, really strong results.

Then I swapped over to the SMSL amp, keeping everything else the same, and again success.

So, I got to thinking what I might have changed from when the results were disappointing to now. It occurred to me, I'm now doing triphase with only three cables attached at the outputs. Previously, I had been keeping four outputs plugged in and flipping the switch for triphase use.

So, could that actually be the issue? Despite the triphase switch presumably breaking the circuit, so only one negative should be employed, could having the second negative output still attached to the unit, and my body, have caused the drop in perceived signal strength?

[zebbg69]

It occurred to me, I'm now doing triphase with only three cables attached at the outputs. Previously, I had been keeping four outputs plugged in and flipping the switch for triphase use ... could having the second negative output still attached to the unit, and my body, have caused the drop in perceived signal strength?

If you had the two negatives attached to your body at the same point (Y-connected into the same electrode), then it makes no difference vs. flipping the triphase switch--assuming no appreciable/stray resistance between the switch and those negative terminals. But if you had the two negatives connected to yourself on separate electrodes with the triphase switch on, then your common electrode is the sum of both electrodes, for a very different feel. Its larger size means a decrease in felt intensity at those commons and a corresponding increase at the positives.

You can get very nice effects from this with a good layout. I like to connect the commons to a pad behind the balls and the base of an anal plug, with the triphase switch on (which eliminates a Y-connector), while the positive leads are connected to cock head and tip of anal plug. Current from the anal tip splits toward the anal base and the pad, while the pad also receives current from the cock head. It is delicious!

[JakofClubs]

I made a version of this stim box with the Doku/NobSound/Breeze Audio amp built inside, with the dummy load resistors and transformers.

JoC_stimbox_front2.jpg

Here's some pictures of the internal wiring. It will run for hours at 1/4 to 1/3 volume and not get warm.

Spoiler: show

JoC_stimbox_top.jpg
JoC_stimbox_Right1.jpg
JoC_stimbox_Right2.jpg
JoC_stimbox_Left1.jpg
JoC_stimbox_Left2.jpg

Here's a more compact version of the above stim box. Same amp and wiring as the black box. I like the way the front panel turned out. It runs lukewarm, given the smaller aluminium case.

JoC_silver_stimbox_front_crop.jpg (156.08 KiB) Viewed 4085 times

Spoiler: show

JoC_silver_stimbox_right_crop.jpg (197.84 KiB) Viewed 4085 times

JoC_silver_stimbox_left_crop.jpg (157.95 KiB) Viewed 4085 times

JoC_silver_stimbox_rear_crop.jpg (184.97 KiB) Viewed 4085 times

JoC_silver_stimbox_top_crop.jpg (694.56 KiB) Viewed 4085 times

I had to add a bit of pc board to get the amp to fit in the case slots. Hot glue and some plastic tube insulation to make sure the amp contacts don't touch the top.

[BobbyS]

EDIT: Ignore diagram below. Just realised the blacks are the wrong way around and on different coils.
I've now assembled as per the diagram but after swapping the black connectors.

It works *amazingly* well. Just the right amount of power and the complexity of sensation compared to the ET312B is nothing short of mind blowing. So many stim files - and the Estim Tower especially - suddenly make SO much more sense than using the 312 with high volume and low MA.

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I couldn't find the exact same transformer - nevertheless, it is a 10W speaker line matching transformer with 8ohms on the secondary.

I've attached a photo of each side of the transformer and I've photoshopped just the BOTTOM diagram of the original post to reflect my understanding of how it ought to be wired. I have built a stereostim unit before, but I'd really appreciate anyone who could give it a look over and let me know if everything looks correct.





Also, should I put a fuse between the amp and the transformer as an extra safety precaution?

[thebiologicalclock]

I'm looking to get the parts to finally build a DIY stereostim using this guide. I'm looking around for a Power Supply currently and there seems to be a lot of discussion, especially in the other thread, regarding safe Power Supplies to use. My main confusion at the moment is from whether or not I should have a Grounding pin on my Power supply, if it even matters. The power supply linked in this OP has a grounding pin, but is currently sold out on parts-express so I found a similar one that doesn't have a grounding pin - linked here https://www.parts-express.com/12-VDC-5A ... ug-120-056

Would this be a safe choice? alternative there's a listing for a 12V 6A (instead of 12V 5A) that DOES have a grounding pin - https://www.parts-express.com/12-VDC-6A ... ug-120-079
However this one is not "double-insulated" with the double square logo, so I believe it would be unsafe to use.

The power supply is the last part I need to find before I'm ready to order all my parts and finally build one of these bad boys. Any help is greatly appreciated, the last thing I wanna do is get shocked with main power

[edger477]

Hello,

I have one DIY unit I built quite awhile ago, which has rather powerful resistors on output (2 one like 10x more resistance than other in series to output and then you connect electrodes between parallel to big resistor) to take most of the current through resistor and make body resistance small factor (so output does not change much with change of contact area/conductibility).

I see these schematics don't use it. As I built mine rather long time ago, can someone fill me in if there is some kind of consensus that units without output resistors are better? Or is just for cost cutting?

[JakofClubs]

My main confusion at the moment is from whether or not I should have a Grounding pin on my Power supply, if it even matters.

My understanding is that that two prong versions are preferred. Do get a 12v one that's double-insulated with the "square inside a square logo" [[]] .

[JakofClubs]

Hello,

I have one DIY unit I built quite awhile ago, which has rather powerful resistors on output (2 one like 10x more resistance than other in series to output and then you connect electrodes between parallel to big resistor) to take most of the current through resistor and make body resistance small factor (so output does not change much with change of contact area/conductibility).

I see these schematics don't use it. As I built mine rather long time ago, can someone fill me in if there is some kind of consensus that units without output resistors are better? Or is just for cost cutting?

Not completely sure of your description, but the basic idea is a single 4 ohm, 10 watt (or higher) resistor (per channel, two total) that "pre-loads" the amplifier so it will see a minimum resistance of 4 ohms. Modern amplifiers don't like to drive loads below 4 ohms because it draws too much current. There have been many, more complex designs, but I'm not sure anyone has demonstrated any benefits in actual use. Some people report liking the feel of different designs better. I think these can be high frequency filters and I have seen additional resistors. I believe someone added a current-limiting diode (?) for added safety.

[ramen]

I'm hunting for components to try this build. I have two questions:

1. Is the amp value of the power supply important? The OP lists two units with different values (3A and 5A). However the only one I could find easily is 12v 2A. Will this be safe?

2. This post proposes a similar build [pic], but including an extra resistor (R2). Other users endorse it here. Can someone explain what does this resistor exactly? And, what would be a good resistor value to use with this build? (Note that the linked schematic uses 5R6 for R1 instead of 3R9.)

[JakofClubs]

I'm hunting for components to try this build. I have two questions:

1. Is the amp value of the power supply important? The OP lists two units with different values (3A and 5A). However the only one I could find easily is 12v 2A. Will this be safe?

You need to look at the specification of the amplifier that you plan on using and see what the maximum current draw is. I looked at the data sheet for the TPA3116D2 listed in the first post and I don't see a clear current recommendation. Others are recommending 5 amps.
You should be able to get a 5 amp, double insulated, two prong power corded power supply for about $11, USD of Amazon. These amps will work with higher than 12 volts, but it's considered safer to limit it to 12 volts.

My understanding is that it's generally safe to have power supplies that can provide more current (amps) than required, but not less. For resistors, a higher watt rating is safe, but not lower. For capacitors, a higher voltage rating is safe, but not lower.