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

[alexjackman]

I've built something very similar to OP but with some additions that might be food for thought for the more risk averse. Instead of connecting a 12V power supply to the barrel connector on OP's device, you can find relatively inexpensive (~$60-75) lithium ion "jump start" batteries on Amazon and many have a 12V out port on them that is also a barrel jack, which makes the connection easy. You can also get an optical audio decoder on Amazon for ~$25 to connect to the RCA audio jacks on OP's device. Then you can use a cheap optical cable to connect to the optical out many PC sound cards have, or you can find a USB sound card with an optical out also. You should power the optical decoder off the 12V or 5V output of the jump start battery also. These two things together (battery power and optical audio connection) ensure complete isolation from both mains power and from your computer. I find the battery lasts anywhere from 4-8 hours depending on use. They charge faster than that, so you could always use two and swap if that's a concern.

[emiumfinal]

Anyone have any thoughts or info on a case to use for a DIY box? I've had one I've used for quite a while, but it was just kind of lying free in a cardboard box, not mounted in a case, and recently I used a metal box I had laying around to mount everything. It seemed to work okay in normal configuration, but it triphase one of the channels was always dead. After a lot of troubleshooting, I think I pinned it down to the output jacks being mounted directly on the metal case, so the the sleeve/ground of the jacks was commonly grounded though the case itself, instead of being fully independent like they were in the cardboard box. Does that sound like a reasonable conclusion, and that the best solution would be to remount it in a plastic box, or insulate the output jacks so they don't share that common ground?

[InfamousPlantain]

After a lot of troubleshooting, I think I pinned it down to the output jacks being mounted directly on the metal case, so the the sleeve/ground of the jacks was commonly grounded though the case itself, instead of being fully independent like they were in the cardboard box. Does that sound like a reasonable conclusion, and that the best solution would be to remount it in a plastic box, or insulate the output jacks so they don't share that common ground?

Yep, this happened to me. I ended up doing the insulation method with heat shrink wrapping the pieces of the output jack that came in contact with the edge of the holes in the metal casing. If you have a 3d printer, you can consider reprinting a proper fitting plate to replace the metal one maybe.

[JakofClubs]

I've been using isolated 3.5mm audio jacks:

Stereo for input:
https://www.amazon.com/Philmore-Isolate ... B00OGLCR3W

Mono x2 for output:
https://www.ebay.com/itm/274570233573

Build pic:
viewtopic.php?f=12&t=23322&start=79

[emiumfinal]

Thanks for the feedback. Ended up ordering a pack of isolated stereo plugs to use for the input and output jacks. I'll probably keep looking for a plastic case also.

[phoopha]

Is it possible to use pots to control the signal output for each channel? I was wondering if inserting them after the transformers would allow me to control L and R output strengths?

[Electro]

Is it possible to use pots to control the signal output for each channel? I was wondering if inserting them after the transformers would allow me to control L and R output strengths?

The pots need to be on the input side before they go to the amplifier.

[emiumfinal]

Is it possible to use pots to control the signal output for each channel? I was wondering if inserting them after the transformers would allow me to control L and R output strengths?

There are designs for that, between the input and the amplifier. If you search for Bonnie Volume Control, that's the one I use.
I was trying to attach it, but can't find it now.

[emiumfinal]

What output is everyone using on the new T7010 transformers that have the 1W, 0.5W, and 0.25W leads? The yellow 1W one?

[Jpl1234]

Hello, long time lurker here. Firstly thank you to lolol2 for your teases and the schematic and parts list for the steresotim box. I received all the parts last week and have drilled out the case and got everything fitted nicely. Next task is to wire everything together. I can follow the diagram and pictures with one exception.

On the stereo amp I am not sure how to wire the bits I have circled in red. I don’t see in the photos how the wired actually connect to this part of the amp? The other bits connected to the stereo amp are the same as in the schematic but the photo is a bit blurry / these parts are obscured so just want to make sure I am doing the right thing.

I have built a basic amp before using folding speakers so know what to expect when it is all working but wanted something more robust and this will certainly do the job. Not a massive fan of soldering but have managed before, I am just very slow!

Many thanks in advance for any help!

Jpl.

[19Hellothere83]

Hello, long time lurker here. Firstly thank you to lolol2 for your teases and the schematic and parts list for the steresotim box. I received all the parts last week and have drilled out the case and got everything fitted nicely. Next task is to wire everything together. I can follow the diagram and pictures with one exception.

On the stereo amp I am not sure how to wire the bits I have circled in red. I don’t see in the photos how the wired actually connect to this part of the amp? The other bits connected to the stereo amp are the same as in the schematic but the photo is a bit blurry / these parts are obscured so just want to make sure I am doing the right thing.

I have built a basic amp before using folding speakers so know what to expect when it is all working but wanted something more robust and this will certainly do the job. Not a massive fan of soldering but have managed before, I am just very slow!

Many thanks in advance for any help!

Jpl.

Hi. You circled the grounding of the input signal. The signal itself is at the core of the chinch connector while the ground is on the outer shell

[Jpl1234]

That makes sense. Thank you for your help. Much appreciated.

[19Hellothere83]

Btw way i now finally added the volume display on the input signal.
I think its very neat, you see the intensity of the two input channels on two ledbars with each 12 leds going from green to orange and then to red.

Since i play files and teases directly to the box I have no Idea if there is an input or if the volume is to low or if the file or tease simply has no sound at this particular moment. Now I do and I think its cool.

Does anyone know how to post videos so I could show you the box with the volume display active.
For now I add a screenshot from the video

Spoiler: show

Screenshot_2022-01-14-10-10-51-693.jpeg (611.96 KiB) Viewed 4200 times

[Jpl1234]

Just a quick note to say I completed my build copying lolol2 original specs.

Lots of testing and then took it for a test run. Happy to say it is working perfectly.

The components from Conrad are very good quality. I would definitely budget a decent amount of time for drilling out the case, cutting and stripping wires, soldering, screwing everything in place and joining the wires. I did all this in many sittings over the course of a week.

My soldering skills have definitely improved from nothing to adequate. I would definitely recommend “helping hands” which are crocodile clips on a stand that help hold things in place while you are soldering.

A decent soldering iron that warms up quickly and has with a temperature display makes a big difference.

Taking time to wrap the wires around whatever you are soldering should pay dividends in longevity.

You will find the potentiometers don’t sit flush. I just put a washer in to balance them out.

I pre-cut and pre-stripped the wires before putting things together. You probably need shortly wire lengths that you expect!

Hopefully this helps someone down the line.

[Jpl1234]

Hello there, is it possible to plug an external battery pack into the mains power supply connector of lolol2 original design?

If so, please could someone suggest a suitable one?