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

[phoopha]

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

Is this unit designed to deliver either triphase or a single channel stim? I note that there only seem to be three output sockets.

[Electro]

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

Is this unit designed to deliver either triphase or a single channel stim? I note that there only seem to be three output sockets.

I'm pretty sure the pictures are showing one port being a stereo input(line in) and the other two are left and right channel. Tri-phase involves connecting two leads together as a common lead to an electrode with the other two going to two other electrodes.

JakOfClubs use of the ports make this difficult to do this directly unless an adapter is made or bought to break the connections out so wiring can be connected that way, or if wiring is used that combines them.

I skipped that entirely and put my transformer outputs into 3 port wago lever nut connectors and then connect my wiring to the electrodes by sliding the wire in and locking it down and that's worked conveniently for me because I can change to and from tri-phase by adding a jumper wire between the two 'common' outputs of the transformers and using a 3 wire output from there and if I want a 4-wire 2 channel setup, I just disconnect the jumper and add back the fourth wire.

[phoopha]

With regards to the internal wiring, is bell wire suitable for joining the components?

[phoopha]

I should have the last few components tomorrow, so hopefully, I'll have my DIY device made by next week.
I tried a few teases today, with my 2B, that are meant to have pain signals, yet felt nothing with the 2B. Hopefully, my new unit should rectify the situation!

[Hopper725]

I have just ordered an SMSL amp to begin a build project. Looking forward to seeing how a DIY set-up compares to my 2B.

Your 2B will sit on the shelf if you build a well thought out unit. Mine just collects dust now

[phoopha]

I tried the SMSL amp today, with some cheap Mourdant Short speakers and was pleasantly surprised by the sound quality.

[phoopha]

Wahoo! My transformers and resistors gave just arrived from the USA.
That means I should now have everything required to build my unit.
I'll post an update when construction begins and comment on how difficult, or otherwise, the process is yo inform others thinking about making their own.

[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

Is this unit designed to deliver either triphase or a single channel stim? I note that there only seem to be three output sockets.

I'm pretty sure the pictures are showing one port being a stereo input(line in) and the other two are left and right channel. Tri-phase involves connecting two leads together as a common lead to an electrode with the other two going to two other electrodes.

JakOfClubs use of the ports make this difficult to do this directly unless an adapter is made or bought to break the connections out so wiring can be connected that way, or if wiring is used that combines them.

I skipped that entirely and put my transformer outputs into 3 port wago lever nut connectors and then connect my wiring to the electrodes by sliding the wire in and locking it down and that's worked conveniently for me because I can change to and from tri-phase by adding a jumper wire between the two 'common' outputs of the transformers and using a 3 wire output from there and if I want a 4-wire 2 channel setup, I just disconnect the jumper and add back the fourth wire.

The input is stereo in the lower center, gold jack. The two silver outputs are mono Left and right.

Edit: The amp combines the input negatives, so there's no point having more than a stereo input. I've been stimming for years and I run this box between 1/4 and 1/3 power. Larger electrodes tend to take a little more power.

[phoopha]

I have literally just finished making my DIY unit!

I haven't permanently fixed anything, yet, as I want to be sure I'm happy with how it is working, but now looking forward to my first test run!

[phoopha]

Okay, so I have got my unit built, and it was a pretty straightforward process, thanks to components with holes, allowing me to twist wires on, and the use of some Wago fixings.

I built mine like one shown elsewhere in the thread, with the parallel resistors (3r9 @ 25w) along with the other resistors joining positive and negative sides (12r @ 25W).

With my transformers, I connected the - to 0 and the + to 4r, as the amplifier (SMSL SA-36A Pro) specifications suggested higher power at 4r (20w) vs 8r (12w) - or have I got my understanding wrong?

On the output side, I connected negative to C and positive to 0.625. When I then tried the unit, I was underwhelmed by the power. Normally, using my 2B, I don't often get above 15 when playing the various videos or Estim games. However, I had my amp turned to full volume, along with my phone, which I was using as my source for a fair comparison.

Consequently, I then changed the wiring from 0.625 to 1.25, but was still left wanting much more oomph from my unit.

Have any of our masters of the electron got any suggestions as to what might be wrong? I was anticipating a far greater sensation than this - it came nowhere near what I get from my 2B using the same source and electrode placements.

[Electro]

The transformers aren't being used the way they were designed to be used, generally a component used for long runs for a public address system so the ohm value is misleading in this case because we are essentially wiring them "backwards" because normally the speaker would be connected to the 4 or 8 ohm taps depending on if it's an 8 ohm or 4 ohm speaker. The thing that matters is the turn ratio of the combination of taps chosen with the transformer. The 8 ohm tap on the transformer is what I'd try along with the initial 0.625 tap to the electrodes. It should be *very* powerful.

[phoopha]

Thanks, I'll give that a try.
Out of interest, would going to 16r provide an even stronger sensation?

[phoopha]

The transformers aren't being used the way they were designed to be used, generally a component used for long runs for a public address system so the ohm value is misleading in this case because we are essentially wiring them "backwards" because normally the speaker would be connected to the 4 or 8 ohm taps depending on if it's an 8 ohm or 4 ohm speaker. The thing that matters is the turn ratio of the combination of taps chosen with the transformer. The 8 ohm tap on the transformer is what I'd try along with the initial 0.625 tap to the electrodes. It should be *very* powerful.

Well, I wired to the 8r and 0.625, but I'm still maxing the amplifier! I'm really confused!

[Electro]

Well, I wired to the 8r and 0.625, but I'm still maxing the amplifier! I'm really confused!

I don't know the turns ratios for the different tap settings of your transformer or even what transformer you are using. I'd assume the 16r tap would be a higher turns ratio, give it a shot.

I don't use the second resistor in my setup, I only have the 3r9 wired in series with the positive output lead of the amplifier which goes to the 8 ohm tap on my transformer(only option for my transformer) and the black wire from the amp goes directly to the 0 or C tap of my transformer. The extra resistor in your circuit will use some power, my build doesn't use it and the official Midistim design left it out for simplicity because it was mostly there for amplifier protection in open circuit scenarios, but that later was determined to not be an issue with the specified SMSL, BreezeAudio, or Nobsound amps.

[phoopha]

Well, I wired to the 8r and 0.625, but I'm still maxing the amplifier! I'm really confused!

I don't know the turns ratios for the different tap settings of your transformer or even what transformer you are using. I'd assume the 16r tap would be a higher turns ratio, give it a shot.

I don't use the second resistor in my setup, I only have the 3r9 wired in series with the positive output lead of the amplifier which goes to the 8 ohm tap on my transformer(only option for my transformer) and the black wire from the amp goes directly to the 0 or C tap of my transformer. The extra resistor in your circuit will use some power, my build doesn't use it and the official Midistim design left it out for simplicity because it was mostly there for amplifier protection in open circuit scenarios, but that later was determined to not be an issue with the specified SMSL, BreezeAudio, or Nobsound amps.

I used the Visatron 10.16 transformers.

I have just ordered the Fosi Audio BT20A amp9to see if that makes any difference.

If not, I'm going to be really stuck and disappointed, as I was hoping for something capable of some serious power. My only other option is to try a different sound source, eg my laptop, to see if that makes any difference.