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

[icehash23]

Thanks for the advice, edger and pvsage! I ended up going back to the yellow tap (~280 ohms or so) with this new build. Heat seems not to be a problem any more, and with the new amp/PSU there are miles of overhead.

Got my M3 hardware today, so the build is done! Only waiting on the swap channel switch, but that'll be pretty easy to splice in later.

I had a couple errors. First the L+/L- output from the filter (input to the amp) were swapped via cable miswire. Caused some pretty alarming buzzing, but I caught it quick enough - no smoke, transformers and amp tested fine after. Second, the master volume pot's ends were reversed - also via cable miswire. Luckily both L and R were backwards, otherwise I'd have been really confused by the symptom. I would've liked to use some header pins and an IDC connector, rather than hacking up some ribbon cables and directly wiring them...

ALWAYS ohm out your circuits!! A DMM that does continuity is super cheap and extremely worthwhile... Building the discipline to follow through on using it though, that's priceless

Anyway, here's some pics. Parts list to follow!

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IMG_20230806_160855.jpg (248.41 KiB) Viewed 8292 times

Aaand the dirty insides:

Spoiler: show

IMG_20230806_160746.jpg (474.7 KiB) Viewed 8292 times

IMG_20230806_160755.jpg (457.41 KiB) Viewed 8292 times

Schematic: TroniC's Pro-Build Stereostim
Other docs: Relevant Docs
(thanks to Stimaddict for archiving)
See attached for some drill templates! Use clamps to hold them on, tape doesn't stick to this coating very well.

I built sections 2, 7 (ish), and 8 into this build. Section 1 will come later, if I really find that I need it. I think the standard is mostly A/Left glans, B/Right prostate... The times when I really need to channel swap, I can just reverse my electrodes and try to remember which volume knob is which

Parts (priced in CAD):

• 1x CONSOLE ALUM 10.18"L X 7.48"W - $63.15
• 1x Nobsound HiFi 2.1 Channel Bluetooth 5.0 Power Amplifier Board Case Stereo Subwoofer Amp - $49.99
• 1x AC/DC DESKTOP ADAPTER 24V 120W - $78.27 (overkill, 12V at 60-80W will likely be enough, as TroniC says)
• 1x CORD 18AWG 1-15P - C7 3.28' BLK - $5.56 (longer if needed)
• 2x Speco Technologies T7010 70V 10W Line Transformer - $25 (USD)
• 4x POT 1K OHM 5W WIREWOUND LINEAR - $34.48
• 2x POT 10K OHM 1/2W CARBON LINEAR - $17.38 (Panel mount pref., I used vertical through-hole Alpha pots from Thonk)
• 10x CONN BANANA JACK SOLDER TABS RED - $18.40 (much cheaper on Amazon, but lower quality too)
• 10x CONN BANANA JACK SLDR TABS BLACK - $18.40 (much cheaper on Amazon, but lower quality too)
• 2x RES CHAS MNT 3.9 OHM 5% 50W - $13.48
• 1x DC POWER JACK 2.5MM PNLMT SOLDER - $2.87
• 1x Panel mount audio jack - $5-10 (I had some already, PJ3410 from Thonk, $2 or so)
• M3 screws to mount amp/resistors/transformers - $13.19
• Optional bigass rubber feet - $8.26 (helps airflow, makes more room for screw heads)
• 1x Bog standard SPST switch ($2-5) for triphase (joins L-a and R-a banana jacks)
• 1x Bog standard DPST switch ($2-5) for channel swap (inverts L/R signal after the audio jack)
• Various perfboards to make wiring pots/filters easier, scrap cables, heatshrink, zip ties, a step drill bit

Total, about $375? But I don't think I'll ever need to build another!

Some notes... you'll have to be comfortable with desoldering an 8-pin ganged pot-button to recreate this build. It could be made a lot simpler by using the bluetooth function on the amp, with software volume controls (individual left/right, plus master). This would skip wiring the 3.5mm input jack, wiring the swap channel switch, wiring the L/R pots and filters, modifying the amp, and wiring the master pot knob.

Also big note, this amp defaults to bluetooth mode. The master volume is also a push button, which you press to switch to 3.5mm, but once it's in the box there's no real indicator of which mode it's in. I don't really like this, but apart from cutting traces to insert audio between the BT DAC and the amp, seems like it has to be done every time. All the other pots can be left at max inside the box, and the EQ switch left to "normal" (didn't seem to matter when the pots are maxed).

[cbttorturelvr]

Ok looking to build one after getting tired of the 2b not working on a lot of teases.
Is there a go to build at this point preferably with US sources.

[Nobody81]

Uhh...lads? Did I fuck up with soldering directly to the pins on the amp because I thought the wire that came with it was too thin? I'm getting 0.8V out of it but no amps.[img][https://drive.google.com/file/d/1F776aZ ... p=drivesdk]

[Míchael]

Uhh...lads? Did I fuck up with soldering directly to the pins on the amp because I thought the wire that came with it was too thin? I'm getting 0.8V out of it but no amps.

That shouldnt be a problem if soldered properly. 0.8 volt is way too low In either way from a current perspective you will only get milliamps from the output. Putting more than 70mA is dangerous, for example 3 seconds of 7mA directly through the heart will result in a certain death. I would not measure the amps just measure voltage.

Back to debugging:

• Make sure that your amp volume is set.

• Make sure every connection is working and you dont have a short. you can test most of them with a multimeter

• Make sure that your pots are working. Test the ressistance with the multimeter. Terminal 1 and 3 should always be the value of the pot. Test the if terminal one and two (or two and three depending on your wiring) are changing values while turning the knob

• Measure the output of the amp. In my case my amp gives out 10v per channel.

EDIT just got access to the image you provided:
Just saw the image you provided:


Its not clearly visible but there could be a short in the audio input. But in general that does not look clean at all i would probably throw away the amp and redo it with wago's

[Electro]

Uhh...lads? Did I fuck up with soldering directly to the pins on the amp because I thought the wire that came with it was too thin? I'm getting 0.8V out of it but no amps.[img][https://drive.google.com/file/d/1F776aZ ... p=drivesdk]

Not sure how you are measuring things, are you supplying input audio to the amp, are you measuring after the output of the transformers, multimeters are designed to work in either DC or 50 or 60hz AC, so measuring things with a multimeter to determine that things are working well can be a crap shoot. Not enough information to even tell you if it's not working.

[Nobody81]

Just measured the voltage output of the amp itself and now I'm getting 12.5-12.6V. I also confirmed the pots worked so there's that. But when i try feeling for amps from the transformers (one's input to 4Ω, the other's at 8, and I checked the outputs at 0.5W-5W and 1.5W-10W) and nothing's coming from them. Is there a way I can test the transformers and also figure out what winding ratio they are? I got them from here.

[diglet]

To test the transformer, attach them to your amp and play a sine wave. Use multimeter to measure the voltage over the low side of the transformer, and then the high side (don't connect anything to the high side). The ratio between them is the approximate winding ratio.

I tested 6 transformers from conrad, but one of them had a manufacturing defect that was difficult to spot. You can try repeating the test above with a 1kohm resistor attached to the high side (Be quick or the transistor will burn..), both transformers should read the same values.

[Nobody81]

(Sigh)...okay, I've tried to see what might be wrong with the transformers, and they're working fine. As a matter of fact, I've tested everything else twice over and saw that the amp was bungled and I had ordered the wrong sized parallel resistors. So I ordered a new amp plus the proper resistors, along with a new set of pot knobs, some pre-wired switches since the other one didn't hold up very well to the solder heat I was subjecting it to, and finally, some of those WAGO terminal crimps I've seen all over this thread. Had everything hooked up and ready to go...and I still got no fuckin' CURRENT!.

I'm almost at my wits end. I think it might be the On-Off switch, but I'm not sure. What should I do?

[Nobody81]

Here is the switch in question.

[Míchael]

Cant tell you much about the switch but what i see is that you go into the transformer with one ressistor in series not parallel. I also see only one ressistor per channel. What schematics are you using ?

In general on a different note i would skip the complicated switch which aim it is to shut off everything at once. For my build I went with a simple on / off switch for power and each channel.

[Nobody81]

Im building this based on lolo2's second iteration with this board, but I was trying different configurations to see if that did anything. This switch is 3PDT which I have wired so "on" let's the current through the wires for power and "off" let's the current only through the cha... shit, I think that's it.

[Nobody81]

NOPE, That wasn't it either. Despite having dropped another $50 on replacement parts, it still doesn't put out any amps. You know what? Screw it, imma go back to pre-built amps and figure out a way to have dual volume knobs and a tri-phase switch unless anyone else can give me a suggestion on what else might be wrong.

[Míchael]

NOPE, That wasn't it either. Despite having dropped another $50 on replacement parts, it still doesn't put out any amps. You know what? Screw it, imma go back to pre-built amps and figure out a way to have dual volume knobs and a tri-phase switch unless anyone else can give me a suggestion on what else might be wrong.

I would not focus on measuring amps tbh. Test all continuity / shorts and test for voltage and ohms. Make sure your connections and parts are working.

1. put in some audio input cables and test for continuity.
2. test if the pots are working correctly. Also make sure you use the right pot for the right channel (i made that mistake and it drove me crazy)
3. check if you have any shorts
4. put power to the amp, It has blue leds that should be on once it has power
5. check input voltage which should be 12v dc
6. put in some audio signal and check the speaker voltage should be around 10v ac. If there isnt any voltage:
check the pots resistance. If the resistance is 0 check the pots on the amp itself
7. check the output voltage (ac) at the transformer.

[Nobody81]

I had it working...I finally had it outputting current when I realized my electrode wires were bad and replaced them. Then, in my excitement, I wired the resistors to the transformer in the wrong polarity and now I think I've not only fried the amp since it started clicking on me when I turned it up, but also my transformer and my power supply too.

(Sigh)

Thank you anyway.

[Míchael]

I had it working...I finally had it outputting current when I realized my electrode wires were bad and replaced them. Then, in my excitement, I wired the resistors to the transformer in the wrong polarity and now I think I've not only fried the amp since it started clicking on me when I turned it up, but also my transformer and my power supply too.

(Sigh)

Thank you anyway.

Ok first of all resistor's dont have a polarity. Remember that transformers generates a buzz sound when you put power in them. In germany we call that "spullenfiepen". You should test the box in parts now to be sure. First only hook up the amp check for the leds and the voltage. Then hook up the transformer.