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

[harryc]

It was connected to a multimeter with the two ends poked into the output sockets, the current seemed to fluctuate but didnt exceed the 2mA

[edger477]

It was connected to a multimeter with the two ends poked into the output sockets, the current seemed to fluctuate but didnt exceed the 2mA

I am guessing that is standard multimeter, which probably has 10A fuse (is almost short circuit) but does not properly detect alternating current. It is probably more than 2A, but you are not connecting it anywhere above waist, and you can test by placing electrodes on your leg and trying with low volume.

[Mikeyh1972]

Still confused about the two switches? Anybody got a US link (amazon?) for each that would work?? Really appreciate it!

[harryc]

Hey everyone, had my build up and operational but the aux port on my amp has just stopped working, the bluetooth still works and all of the wiring has been tested, the problem is isolated to the port.

This is the amp i'm using
https://www.amazon.co.uk/gp/product/B08 ... UTF8&psc=1

any help is much appreciated

[andyupnaway]

Hey everyone, had my build up and operational but the aux port on my amp has just stopped working, the bluetooth still works and all of the wiring has been tested, the problem is isolated to the port.

This is the amp i'm using
https://www.amazon.co.uk/gp/product/B08 ... UTF8&psc=1

any help is much appreciated

Check that there are no active bluetooth transmitters, i.e., your laptop, cell, etc. If there is no switch to manually select aux or BT input, most of these mini amps are designed to default to BT. If BT signal is present, it will lock on to that and ignore the aux input.

[JakofClubs]

Still confused about the two switches? Anybody got a US link (amazon?) for each that would work?? Really appreciate it!

Looking at the last schematic posted, you can use a regular SPST switch for the tri-phase. They show a SPDT, which could be used and only hook up two poles (the center and one other).

The complex switch (3P3T) is trying to switch the input power and the outputs at the same time. Nothing wrong with that but I would say it's overkill. You just need a switch for the power, and a regular SPST will do for that.

https://www.amazon.com/MTS-101-Position ... B0799LBFNY

[Mikeyh1972]

Thanks so much for the help! Unable to order that transformer that is recommended in the US it seems? Anybody got another recommendation or a link to help?

[Tekkkie]

Hello everybody,

I am trying to build the device (V2) as listed on page 12 of this forum.
I have read most of the replies on here with great interest.
This will be my first E-stim experience and my first serious electronic diy project.
So far it has been quite a bit more expensive than expected to get all the parts delivered to where I live.
That is fine, it's a hobby project. Whatever.

I just have 1 potentially major issue...

2x 3.9 Ohm 50W resistors - 6.98€

The 3.9 ohm widap resistor has a 20 week expected delivery time at Conrad...
I tried to order directly at Widap, but I got an email reply that the item is wrongly listed as "in stock".
Does it need to be the 50Watt version because of temperature issues?
Can you suggested any reasonable alternatives?

I found:
25Watt version, but I suspect it will run too hot (without cooling element)?
75Watt version, but it is a bit more expensive.
100Watt version, but it is even more expensive, and also listed as out-of-stock...

How tight are the tolerances?
I think I found a good alternative on a different website, but it is listed as 5% tolerance =(

Also, there was a mistake in the delivery of the 22ohm resistor.
So I actually do not have those yet, but they should be easy to get.
Now I also read some comments on here that they don't add a lot. Can I just leave them out?

Any feedback is appreciated
Thanks in advance =D

[Electro]

The 25 watt version is just fine, mount any resistor that you find/use to a metal plate for cooling. Chassis mount resistors are what you want(flat surface on the bottom for mounting, usually with screw holes but I never screwed mine in place). You could use a thermal paste and screw it in place, but it's not really needed because all you really need to do is make sure there aren't any machining related air gaps between the resistor and the metal plate and I found superglue does this well enough and the heat hasn't separated the superglue(CA glue) from my metal plate.

[Tekkkie]

The 25 watt version is just fine, mount any resistor that you find/use to a metal plate for cooling. Chassis mount resistors are what you want(flat surface on the bottom for mounting, usually with screw holes but I never screwed mine in place). You could use a thermal paste and screw it in place, but it's not really needed because all you really need to do is make sure there aren't any machining related air gaps between the resistor and the metal plate and I found superglue does this well enough and the heat hasn't separated the superglue(CA glue) from my metal plate.

Thanks for the quick reply.
Follow-up question:
How important is it to mount the resistor on some kind of plate?
I understand that it will essentially function as a cooling fin.
But what about plastic cases?
Or what I am currently planning: starting without case, so I can test the device before deciding what to do with it?

[lolol2]

You can get any ~4Ohm resistor, the tolerance isn't anything you have to care about.
25W should also work fine, the 50W version was just used because prices are mostly kind of the same for all versions.

Otherwise you can also use other brands, for example:
https://conrad.de/de/p/ate-electronics- ... 21618.html

The v1 version was without the parallel resistors, so you can also start without them.
Maybe add them later when you can get some.

To the second question about cooling... I have everything in a plastic case without any additional cooling.
Never had any problem, also not in very long 3h session with very high power.
V1 was more effected by heat problems, the new amp is more efficient.

[Electro]

Mine gets hot and I've measured it at 160f/70c at the end of 2+ hour intense sessions, but I also don't have a fan and the metal plate is about the size of an index card and is a very thin piece of aluminum without fins. Perhaps I just use more power but I wouldn't mount my resistors directly to a plastic case with my usage. perhaps a cooling fan would allow that but I wouldn't want to melt ABS plastic because that stuff releases toxic fumes and anything 3D printed that isn't ABS would melt at a cooler temperature or would also be toxic(nylon or polycarbonate but these are also more difficult and expensive to print with anyway). My 2 cents based on personal experience but mileage could vary, I also max out the DG Lab Coyote once conductive silicone tubing has some age and many people can't or haven't maxed that device out, so I could be a special case.

[andyupnaway]

...once conductive silicone tubing has some age.

My experience is that CR is not very efficient. For that reason, I tend to prefer to use TENS pads when possible. Also, I will trim a 2" square pad to appx 0.75" wide (still 2" long on axis with the electrode wire) which helps to focus signal better. If you want the best experience, try the "silver" electrodes (hard to find and expensive). They are the best for stimming. Signal is smoother and more evenly distributed with fewer hot spots than standard carbon pads.

One other thing to consider is the age of the CR. My understanding is that the conductivity does tend to degrade over time. Also, exposing the CR to excessive heat, such as sterilizing in boiling water, can also affect performance.

Or, try copper electrodes if you want the most efficient but remember to go slow and use conductive gel!

[JakofClubs]

On the heat issues, I believe running a high-pass filter between the amp and the transformers, such as a bipolar capacitor in the 100uf to 330uf range, 35v, will filter out some undesirable low frequencies and put less load on the amp and I believe this could also keep the resistors cooler. Personally, I prefer aluminum enclosures and mount the resistors to that.

On the conductivity of CR tubing, I run a wire down the tubing so it doesn't have to conduct the length, just across the wall section. I use stainless steel safety wire for the corrosion resistance and flexibility, but copper would work. Also, there are different types of CR tubing with different conductivity. A lot of the Ebay stuff is not very good. HappyStim-usa has the good stuff. Joanne's electrodes also uses the good stuff.

http://happystim-usa.com/catalog/c1_p1.html
https://www.sexmachinereviews.co.uk/sho ... c/43087006
https://www.amazon.com/pcs-Nichicon-ES- ... B075K4698T

[Electro]

...once conductive silicone tubing has some age.

My experience is that CR is not very efficient. For that reason, I tend to prefer to use TENS pads when possible. Also, I will trim a 2" square pad to appx 0.75" wide (still 2" long on axis with the electrode wire) which helps to focus signal better. If you want the best experience, try the "silver" electrodes (hard to find and expensive). They are the best for stimming. Signal is smoother and more evenly distributed with fewer hot spots than standard carbon pads.

One other thing to consider is the age of the CR. My understanding is that the conductivity does tend to degrade over time. Also, exposing the CR to excessive heat, such as sterilizing in boiling water, can also affect performance.

Or, try copper electrodes if you want the most efficient but remember to go slow and use conductive gel!

I find my best electrodes are 3D printed in Protopasta Electrically Conductive composite PLA filament, I can design a perfect fitting electrode that has the right amount of flex to fit properly and the electrical resistance is less than TENS pads or conductive silicone tubing. I've messed with wetted cloth/sponge type stuff, copper, etc wire and out of all the pre-made stuff, I prefer the conductive silicone like the happystim-usa stuff, but my 3D printed electrodes last longer, at least until I accidentally snap one by mishandling like stepping on it. It's expensive filament but it's cheaper than the pre-made stuff on a per electrode basis, but you can buy a small 125g coil of it for $15 if you are nervous, but my local 3D printing shop had the 500 gram spool in stock, so I committed to the $50 purchase instead of shipping something smaller and I've been happy with it. The trouble is I don't use the little pin connectors for it, so for the Coyote I use the conductive tube because I can slip the pin in place instead of trying to connect the Coyote to my wire connections. ..stereostim makes things either because I just slip wires into Wago Lever Nuts, but that's another topic.