[Tutorial] Building your own DIY E-Stim Stereo Device

[Nobody81]

I FINALLY FUCKIN GOT CURRENT AFTER A MONTH OF WAITING TO BY A NEW AMP! Bonus, the transformers and the power supply are fine though I've bought extras along with the amp just in case but still...wheewww. Now I can finally end NNN with a bang!

[Art2034]

Hi guys
My first post but just had to thank Iolol2 for his clear explanation of how to build a DIY box.
Started estim last year and quickly progressed to a 2B which is great albeit with the limitations all of you know about. Finally decided that I needed the full experience and therefore had to build my own box. Followed Iolol2 revised build (page 12) and collected up all the bits needed.
Assembled it yesterday and tried it last night - wow!! What a blast, the difference between dial up and fibre! if it wasn’t addictive before it certainly is now.
Thanks for all the advice - mine to anyone considering this is just do it, read the whole of this post but don’t get bogged down in the technical stuff, you don’t need to know all that. Enjoy and thanks

[Nobody81]

I..I don't know what happened.

I got current through one channel but not another, so I figured after testing the other components of that non-functional one, that it had to have been the wiring of the audio inputs and volume knobs.

After that, something strange happened. I tried testing that one channel again, but still nothing. Then, as I went to turn down the volume on my laptop where i was feeding the machine a signal, i got shocked everytime my fingers got close enough to the copper contacts under the key. Literally everything i touched that was metal shocked me but i felt no current where it was supposed to. Even weirder, i tried the channel i know that worked, and the same thing happened.

Now im thinking i got another board fried for something stupid I did, and im probably just gonna go back to what works for me which is the Breeze Audio amp Tronic's got listed in his schematics.

But just in case anyone knows, what happened to me exactly?

[fishyfish]

Hey,

I'm looking to build one of these too. All other parts were easy to source but the transformers seem more tricky.

Model: Compact transformer unencased, vertical model
Primary: 230VAC 47-63Hz
Secondary: 24VAC
Power: 25VA
Dimensions: 52 x 55 x 89 mm

voltage: 2 x 24V
current: 2 x 0.250A
transformer can be screwed onto a PCB
operating temperature: -20°C to + 70°C
dielectric strength: > 5000V
meets the following norms: BS 3535, VDE 0551, IEC 742
a thermal fuse can be fitted
primary AC line: 230V - 50/60Hz (parallel and series connection)
other VA's and sizes available on request: up to 250VA

Would either of these happen to be suitable for the project?


Edit: Found a better alternative

[Electro]

You want an audio line transformer of a reasonable physical size that has the right turns ratios, the one described doesn't sound like it is one. People are able to find the correct ones depending on their location. If you are looking for the right one, knowing your country would help with providing a suggestion as others in probably every major country/continent have built a Stereostim.

[fishyfish]

You want an audio line transformer of a reasonable physical size that has the right turns ratios, the one described doesn't sound like it is one. People are able to find the correct ones depending on their location. If you are looking for the right one, knowing your country would help with providing a suggestion as others in probably every major country/continent have built a Stereostim.

I'm from Finland.

They have some audio related transformers here: https://en.uraltone.com/electronic-comp ... hokes.html

I'd appreciate help very much! I'll also study the turn ratios. I suppose it's not always listed?

[Dramya]

I followed the listing of viewtopic.php?p=326644#p326644 and I could find most of the items with relative ease, but I think I have a few interesting links that could be added to the item list (German Amazon, but they deliver to other countries)

Power Supply:
https://www.amazon.de/-/en/dp/B0BF9T6X6 ... tails&th=1
This one has the same properties as the original listed item, 12V 10A 120W, and the show picture is accurate as it is indeed double insulated. Way better price then the one mentioned somewhere in this topic that is specifically meant for lab equipment.

Stereo Amp:
https://www.amazon.de/-/en/dp/B0B2K8KPP ... ct_details
Same exact board but with a TPA3116D2 chip, which is (as far as I can find) a better performing chip then the CS8673E chip one in the original listing. If it actually is I will find out soon enough. Also, it is of German make, so I'm reasonably sure it is not a fake one with a totally different chip under the heat sink.

I still have to get the rest of my orders, but as soon as I get to put it together I will post an update.


I also have a question, I have struggled to find the Stereo Amp that closely resembles the one listed but should I even have cared? Is there a lot of difference between those Amp's? Could I have chosen a different one, maybe of different make and type?

I also heard from Edger477 that the 22Ohm resistors are not actually needed, what was the reason to include them in the original design?

[Electro]

The TPA3116D2 chip is what you want and it has a good sized heat sink on it, so that looks like a good amp.
The power supply looks good, you'll never pull more than 5 amps from it.

[Dramya]

The TPA3116D2 chip is what you want and it has a good sized heat sink on it, so that looks like a good amp.
The power supply looks good, you'll never pull more than 5 amps from it.

This worries me for a tiny bit, I took a rather generic electronics enclosure without any air holes in it, does this chip generate a lot of heat? Enclosure is big enough, so it should have should have enough air in it to take a bit of heat, but I think I should consider punching some holes in it too.

[Electro]

This worries me for a tiny bit, I took a rather generic electronics enclosure without any air holes in it, does this chip generate a lot of heat? Enclosure is big enough, so it should have should have enough air in it to take a bit of heat, but I think I should consider punching some holes in it too.

The amp doesn't generate much heat, I bought a cased amp that has the TPA3116D2 instead of one of these and it doesn't have any ventilation at all and the case doesn't seem even slightly warmer than its surroundings.

The resistors do make heat though and they are mounted to a 3" x 5"(75mm x 150mm) thin metal sheet as a heat sink that's exposed to air and the metal sheet feels hot to where you can still hold your hand on it, but not for more than a few seconds during longer and more intense stim sessions. I wouldn't mount the resistors directly to plastic.

My resistors and transformers are inside a plastic box but the metal sheet is the lid and I mounted the resistors upside down onto that lid using a healthy amount of CA glue(standard clear superglue), no other ventilation for the box but the lid is exposed to the air around it. ..again I don't have my amp inside this since I have a cased amp. So my rig is the cased amp and the "speaker wires" from the amp run through drilled holes for each of the four wires and the output wires from the transformer come out of the box on the opposite side. So basically I've more or less got two boxes roughly the same size that are tethered together.

[JakofClubs]

I also heard from Edger477 that the 22Ohm resistors are not actually needed, what was the reason to include them in the original design?

Apparently, some older amps worked better with the additional resistor. Edger477 did fairly extensive research on the modern TPA3116 amps and found that they don't benefit from it and it's a waste of power. They aren't required for safety.

IIRC it was originally called a smoothing resistor. I have a pair in my box with no noticeable power reduction. I subjectively think it feels a little less spikey, but it depends on the track. I should add a switch to bypass them on my box to see if I still think that's true.

[edger477]

Edger477 did fairly extensive research on the modern TPA3116 amps

Actually, I did not research myself, I suspected that the reason for them might have been that older amps did not pump current until they detect some minimum load, and asked about it in Joanne's discord (there are some very good electronics engineers there). On modern amps, especially with a transformer that has static resistance (when you measure with Ohmmeter) that is 4 or 8 Ohms (the side we connect to amp), these parallel resistors are just waste of power, and also source of unnecessary heat.

[tommarr]

I liked the case lolol2 mentioned in his post here viewtopic.php?p=326644#p326644. However it was no longer available and there seemed to be nothing similar in amazon / ebay. After some searching I found that bahar sells the case from their website in all amounts.

Here is the one I believe lolol2 had in his pictures https://bahar-enclosure.com/products/bd ... 70-x-60-mm
Ordered a bit larger one to have more space to lay out things https://bahar-enclosure.com/products/bd ... 10-x-65-mm

Will see if the shit ever arrives from China via bahar website Shipping to EU was around 25eur, not cheap but bleh whatever. Ordered two and will probably build and sell the second one to cover costs a bit. Amazon.de also has nice 25eur shipping for under 100eur purchases, conrad also 25 eur. Costs just going up everywhere

Stereo Amp:
https://www.amazon.de/-/en/dp/B0B2K8KPP ... ct_details

And sorry guys, I think I ordered the last ones Already have few TPA3116 but the form factor ain't that nice so that amp was easy pick

But I think I finally got enough of my wire mess without any enclosure minimalistic diy-estim. Time to dig the soldering iron from closet and make a nice box

[JakofClubs]

Edger477 did fairly extensive research on the modern TPA3116 amps

Actually, I did not research myself, I suspected that the reason for them might have been that older amps did not pump current until they detect some minimum load, and asked about it in Joanne's discord (there are some very good electronics engineers there). On modern amps, especially with a transformer that has static resistance (when you measure with Ohmmeter) that is 4 or 8 Ohms (the side we connect to amp), these parallel resistors are just waste of power, and also source of unnecessary heat.

My mistake. Perhaps it was Diglet that did the testing?

[edger477]

We did some tests together with scopes and different loads but I would not call that extensive since it did not involve different amplifiers for verification. I did rebuild my boxes without these resistors (old boxes had them) and can confirm that output did not become worse for it.