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

[fossie67]

so i am building a new unit and want to ask if this is ok

https://www.ebay.co.uk/itm/146161214334

[picofarad]

so i am building a new unit and want to ask if this is ok

https://www.ebay.co.uk/itm/146161214334

yes, should work.

[fossie67]

was going to use 8 ohm but what tap should i use on other side ?

[fossie67]

also can someone confirm that i am wiring up correctly please ;
so from amp to resistor resistor to 8 ohm tap then say 4w tap to electrode .

[Ok_Cloud_1034]

Finally got around to building a stereo E-stim unit based on the info in this thread.
This has a triphase switch, a Channel B invert switch and a switch to disconnect the output terminals from the transformer outputs. It has leds for power, triphase and channel outputs.
It also has a remote to turn off the power supply instantly.
It works really nicely, next project is to bulid the FOC-Stim and get to grips with the various apps to make it work.
Attached some pics of stages in the build.

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[maxmadness69]

Finally got around to building a stereo E-stim unit based on the info in this thread.
This has a triphase switch, a Channel B invert switch and a switch to disconnect the output terminals from the transformer outputs. It has leds for power, triphase and channel outputs.
It also has a remote to turn off the power supply instantly.
It works really nicely, next project is to bulid the FOC-Stim and get to grips with the various apps to make it work.
Attached some pics of stages in the build.Amp-1.jpgAmp-2.jpgAmp-3.jpgAmp-4.jpgAmp-5.jpgAmp-6.jpgAmp-7.jpg

That looks very professional. I would love more info as to the parts you used and the specific transformers, resistors and amp board. Also what you think about it, now that you have used it for a while.

I am brand new to this field, reading and learning :D

[Ok_Cloud_1034]

Thanks for your comments. Parts list in spoiler.

Spoiler: show

Amp: DF Robot DFR0803 (50W 5 to 27V) (Mouser 426-DFR0803)
Transformer: 2x Visaton 1803 (10W 100V line) (Mouser 243-TR10.16)
Resistor: 2x PATIKIL 50W 4 Ohm Aluminum Shell Resistor (Amazon)
Capacitor: 2x Bipolar Electrolytic Capacitors for Audio 100uF 100V (Ebay)
Switches: 3x Heschen Miniature Toggle Switch (Amazon)
Sockets: Same Sky 3.5mm (Mouser 179-SJ3-35052B)
Heatsink: Aluminum Heatsink 60x150x25mm (Amazon)
Power Supply: Certified 12V 5A 3A 2A 1A Power Supply 240V to 12V Transformer DC Power Supply 60W (Amazon)
Case: 80*170*130mm/210*140*270mm Blue Metal Enclosure Project Case DIY Junction Box (Ebay)
BTW also available from Mouser are the key parts for FOC Stim:-
Controller: STMicroelectronics (Mouser 511-B-G431B-ESC1)
Transformer: 3x Xicon (Mouser 42TU400-RC)
Capacitor: 3x Murata Electronics 10uF 50V (Mouser 81-RCEC71H106K3K1H3B)
Inductor: 3x Fastron 220uH (Mouser 434-09HCP-221M)

Having used it now on many occasions I am very pleased with it and the large heatsink ensures that it barely gets warm.

[maxmadness69]

Thank you for responding. That is a good transformer and amp choice. I have ordered the same set. I do have a question as to the capacitors. I do not see them in the original schematics and am curious as to how you wired them in and what your purpose behind them are. I was thinking along the lines of removing DC leaking from the amp going into the transformer. As in coupling caps, but could not work out exactly how you wired them from your pictures. I dabbled in tube amps for a bit so have a number of high voltage caps in the parts store.

[Ok_Cloud_1034]

The capacitors are in series with the 4 ohm 50W resistor and create a high pass filter.
The use of these series capacitors is discussed in some detail on [Tutorial] Building your own DIY E-Stim Stereo Device.
They must be bipolar capacitors. If you want to change the cut off (-3db point) then you can use different capacitors
eg 330uF would lower it to 110Hz, 100uF gives 350Hz roughly.
I hope your build goes smoothly and you are pleased with the result.

[silajim]

Finally got around to building a stereo E-stim unit based on the info in this thread.
This has a triphase switch, a Channel B invert switch and a switch to disconnect the output terminals from the transformer outputs. It has leds for power, triphase and channel outputs.
It also has a remote to turn off the power supply instantly.
It works really nicely, next project is to bulid the FOC-Stim and get to grips with the various apps to make it work.
Attached some pics of stages in the build.Amp-1.jpgAmp-2.jpgAmp-3.jpgAmp-4.jpgAmp-5.jpgAmp-6.jpgAmp-7.jpg

Hi, could you share the schematics please? It seems quite interesting and an alternative to the Tingler in Europe, but without the schematics I will surely mess something up

[Corndogville]

Again, so the black common that goes to the electrode is on the opposite side of all the other wires we're using? Just want to confirm so I don't fry something.

That is how it looks like by the markings on the pictures.

Also, is it safe to use nylon zip ties to secure the transformers, at least temporarily, or do they get hot enough to melt them?

If transformer gets that hot then something is very wrong.

I'm clipping off the stripped end and double shrink tubing them, one smaller piece to cover the cut wire

On mine I did similar, I put shrink tubing down near transformer and then folded wire back into it, did that with each wire, and then one large shrink tubing for all of them.

OK, I finished the thing, I think. The output jacks are just hanging loose right now, but I shrink tubed all the solder connections, so hopefully nothing can touch anything when I test it. The amp board's currently held in place by the wires, lol. I used green and black for the power connector. Since most folks seem camera shy about their messy builds, I figured I'd take one for the team:

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I shrink tubed the entire length of the legs of the amp side of the resistors, leaving just enough to go into the terminal block, and clamped them, leaving me plenty of stiff but flexible leg to help me do cable management with. I tagged the other ends down with hot glue, to keep the resistor touching the aluminum plate, as a heat sink, if that makes any sense. The resistors aren't exposed anywhere. The transformers and power jack are held down with zip ties. I tested the board with my on-hand AC adapter to make sure the power light lit. The fixed voltage adapter is coming sometime today, but I'm just gonna test the box with what I have on hand.

If I don't post back soon, I died.

I just wanted to post a safety update for other folks who used the same amp I did (the red board). If you have this one, try turning your box upside down and shaking it. If you hear a rattling sound, that means the crappy little heat-sink fell off the board.

I'd noticed the bottom of the box was getting really warm, and I think that's why. I did buy a spare at the time and am currently turning my house upside down, trying to find it. I had tried super-gluing the old one back on, but I read that's not safe and that cyanoacrylate (the active ingredient) is bad for circuit boards and can ruin traces, and it didn't even work (I was too afraid to use it after reading that anyway) because I can hear it rattling around in there again.

If someone can recommend an amp with a similar form factor that's higher quality (but still inexpensive hopefully) please let me know.

Be safe, all!