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

[Stefanal]

Hello All!

Thanks for the shared knowledge. After much research i will give it a go to build something. I will go mostly with the original design and some parts from lolol2 tutorial because i am based in europe. I am a complete beginner and have a few questions that maybe some people here can answer.

1. I will go for 2 amps like lolol2 suggested a few posts ago to have separate control over left and right channel without complicating things much. But how will you connect power to both? I got a 12v 5A power supply. Can you just connect the wired to both amps?

2. Is it good to attach the 2mm pins right after the tranformer? Or is it better to first solder the wite to a female 2mm or 4mm plug?

3. I got the tranformer from conrad. https://www.conrad.nl/nl/p/elma-tt-iz18 ... 16104.html. These don't come with preattached wires. Can you just soldet the wire on those hooks? Is there a technical term for this so i can maybe find a tutorial.

4. What is a good way to test these things? I got a multimeter.

5. Can you play the sound from your phone using a usb-c to 3.5mm adapter or will that distort the sound?

6. More from a end user perspective later on: i notice that most anal toys are sold bipolar. Could you also just plug in 1 pin and then another one somewhere else in for example a triphase setup?

I know these are a lot of questions. But hopefully some can help me out . Thanks in advance! If you are dutch (like me). I found reliable dutch webshops where i ordered the parts. So i you want links let me know.

[edger477]

Can you just connect the wired to both amps?

Yes, just connect both + together to supply and both - together to - of supply.

2. Is it good to attach the 2mm pins right after the tranformer? Or is it better to first solder the wite to a female 2mm or 4mm plug?

I use 4mm female plugs on box, and then silicone lab banana cables (I build electrodes with female 4mm plugs too). But it is personal preference.

These don't come with preattached wires. Can you just soldet the wire on those hooks? Is there a technical term for this so i can maybe find a tutorial.

You can solder to these terminals directly, but I would probably get the cold press terminals (this set probably contains a right one but hard to say, would need to measure and find a proper one https://www.amazon.de/-/en/gp/product/B0BC8VNDZ4), because with crimped terminals you can easier change the input/output taps for experimenting and if you need to take box apart for maintenance.

5. Can you play the sound from your phone using a usb-c to 3.5mm adapter or will that distort the sound?

that adapter is just a small sound card... you would have to test how it works, some have ok sound

6. More from a end user perspective later on: i notice that most anal toys are sold bipolar. Could you also just plug in 1 pin and then another one somewhere else in for example a triphase setup?

Yes, and you can also connect both poles of bipolar toy to same wire (combine them into unipolar).

[Stefanal]

Thanks a lot for the answers! I will update when i have finished something

[Stefanal]

Hello, one more question from me.

Is the amp also suitable? I feel like it is very similar to the original tutorial. Different brand but same chip.
https://www.amazon.co.uk/AZDelivery-TPA ... B09PRJQYPB

[senorgif2]

Hello, one more question from me.

Is the amp also suitable? I feel like it is very similar to the original tutorial. Different brand but same chip.
https://www.amazon.co.uk/AZDelivery-TPA ... B09PRJQYPB

that will work. Like you said the chip is the same.

[mini33]

So are all TPA3116's the same?
Also looking at "MidiStim_partsList_2020-06-28.pdf" which i have included as an attachment i see
"> 2x20W RMS @ 4 Ohms, < 2x35W RMS @ 4 Ohms" which i have no understanding of, any help would be apreciated.

[bigfoot58]

Thought I would post a photo of a solder-less device. Just a functioning prototype for now but it might help new folks with the transformer wiring which was the most head scratching part for me. Eventually I will get this thing boxed up and may even add a second amp for separate volume control of the left and right channels.

[Bigcars]

I have the following tentatively set up:

1 - Breeze Audio HiFi Class 2.0 Audio Stereo Digital Power Amplifier TPA3116 Advanced 50W+50W Mini Home Aluminum Enclosure amp https://a.co/d/22hG149
1 - 12v 5a 60w double insulated 2 prong power supply
2 - 25W 3.9 ohm resistors
*** 2 - ? resistors (In parallel) ***
12 - terminal blocks
1 - SPST Light Duty Toggle Switch (Trode Power)
1 - DPST Heavy Duty Toggle Switch (Unit Power)
2 - 70V 10W Speaker Line Matching Transformer

On order:
1 - Triphase switch — Twidec/8Pcs Mini Toggle Switch SPST 2 Position 2 Pins ON/Off AC 125V 5A AC 3A 250V with Pre-soldered Wires MTS-101-X https://a.co/d/eR5EvXw
5 - 4mm female banana jacks for L, R, Tri —- 10Pcs Black and Red 4mm Banana Jack Socket Female Adapter Panel Mount Binding Post for 4mm Banana Plug Connectors https://a.co/d/0XkHey9
1 - Project Box — JIUWU Aluminum Project Box PCB Enclosure Case Sand Blast Reinforced Split for Audio Amplifier DIY Power Supply Signal Amplifier, 106x55x150mm (WxHxL) https://a.co/d/fpkpZGS


1. What resistors do I use for the parallel setup?
2. How should I tackle POTs for level and balance with the individual electrodes?
3. Is it easier to swap out the amp for one with these level controls?
4. Adding the triphase switch just joins the 2 black lines to a new common line so I have L, R, Common, correct?
5. Would it be beneficial to add a rechargeable battery pack to this setup?
6. I’m ending up with 2 outlets required which is kind of a bummer
7. I need to accommodate 2 RCA (amp) -> 3.5mm input (stimbox) OR 4 banana jacks (amp) -> 4 banana jacks (stimbox). Is there a preference?
8. I also need to assess the gauge of wire for the power and for the rest of the build as they will be different

[edger477]

1. What resistors do I use for the parallel setup?
2. How should I tackle POTs for level and balance with the individual electrodes?
3. Is it easier to swap out the amp for one with these level controls?
4. Adding the triphase switch just joins the 2 black lines to a new common line so I have L, R, Common, correct?
5. Would it be beneficial to add a rechargeable battery pack to this setup?
6. I’m ending up with 2 outlets required which is kind of a bummer
7. I need to accommodate 2 RCA (amp) -> 3.5mm input (stimbox) OR 4 banana jacks (amp) -> 4 banana jacks (stimbox). Is there a preference?
8. I also need to assess the gauge of wire for the power and for the rest of the build as they will be different

1. None
2. your amp has only one POT... best to use balance in windows for that
3. I did not find any good amps with 2 channels and separate controls, but I built 4-channel box anyway with this one https://www.amazon.de/-/en/gp/product/B087FWWVB6/
4. yes, correct, but with more complicated switches (on-off-on double ones that have 6 wires) it is possible to also make common from red ones (it is same but changes stroking direction)
Since you are using banana jacks for output, you could even do without switch and just get these cables https://www.amazon.de/-/en/gp/product/B07ZVQDH1T/
Or something similar, then you can connect black to black with cable and there is pass-through to connect another one for electrode.
5. If you got a good PSU then no, but it cannot hurt
6. ?
7. I think amp has 4x4mm bananas for speakers not RCA. RCA are for input from PC
8. power from PSU is probably 1.5mm square or less, so that is about 15 awg, and from amp to stim box you can use 14-ish

[breadfan]

Spent the last day reading every word of this entire thread, twice. So with the basic build, long as we're using a TPA3116, we should NOT include the parallel 10-20 ohm resistor??

[Electro]

Spent the last day reading every word of this entire thread, twice. So with the basic build, long as we're using a TPA3116, we should NOT include the parallel 10-20 ohm resistor??

That's correct, it's not necessary and people who who added it generally don't have any difference in the Estim feel of the box either way.

[breadfan]

That's correct, it's not necessary and people who who added it generally don't have any difference in the Estim feel of the box either way.
[/quote]


Guess I'll leave it out on the next build

[Hellme]

Hi,

I want to build also a device with this amp: https://www.amazon.de/-/en/gp/product/B087FWWVB6/

I have this Transformers: https://www.conrad.de/de/p/elma-tt-iz18 ... 16104.html

So i am not shure how to wire the Transformers safe and correct.

1. Do I need the 1k resistor in the Output If I use 16 Ohm, 0,65W setup?

2. Or better use 3.9 Ohm 10W setup in the input line of the transformer?

Cheers
Hellme

[Mistypanda22]

im looking to build this device too. mainly after i found out lolol2's version, most parts are inaccessible to American shipping
ive been wondering though. apart from the basic circuit picture, is there a more "fleshed out" guide or anything that id need to know?

[Mistypanda22]

just have a few questions on the way this is supposed to work in general, as a lot of sources kind of... don't blatantly tell people how things work, and it would come down to trial and error.
1.)
looking at this general box, there's 4 slots. i get that the left is audio input, and i assume the right is the power input
the left and right are for the electrodes that you'd put on yourself, but.... is there any specification as to how they should be placed? like if one should be above the other? does it matter? idk

Spoiler: show

looking through the thread, I've noticed a lot of changes/ backtracking(it feels like) on how to hook up the transformers, and I've also got a few questions for it too

2.) looking at the transformers, what is the ideal way to hook them up? on the schematics, most of yall are saying to hook the power to ground and 8 ohms, but then go and say DONT do that? which is it
3.) also looking at the transformer, where should the positive electrode go? the 70V-0.62W slot or the 25V- 0.5W slot? i keep seeing contradictions so idk what was the consensus on these. i do know negative is to ground tho

Spoiler: show

4.) how does one test the device after you built it? where would you try and test to see if the circuit is running ok, and how would you go about testing it on the human body?

5.)most pictures I've seen don't really have connections for a person, so im not sure how one goes from the 2 leads to a single wire plug that can be used to attach conductive lassos or rings and stuff. im really ignorant on how its supposed to work

6.)what the heck is a tri-phase
7.) ive seen a few schematics that have a parallel 10 ohm or higher resistor. is that recommended? or should i stick to the basic in series 3.9 ohm resistors?


8.) ive got a number of the key things for the build, but feel like im missing something in terms of actually making it. like proper switches or the connections from the electrodes to a jack to use. what should i get on top of the base 6 items in the head post?

overall, im lacking a lot of base knowledge of estim devices and how they work, and would like to know WHERE i can learn more about how they work, how to test them, and how to play with them