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

[GH-Hoss]

If anyone in the US has managed to source parts for a successful build, could you share your shopping list possibly with links? Thanks!

This thread has a simple build and links to US parts.

viewtopic.php?f=12&t=23322

Thanks. I've been looking at that build also. I'll check it out again and see how it goes.

[19Hellothere83]

I just wanted to show off my device - build it identical to the schematics in the first post. Had some problems fitting everything in the box ... for now only tested it on my leg ... it feels completly different than all other commercal devices i own.
I am somehow scared of connecting it to my junk
Will try it with a tease next week probably

[19Hellothere83]

I am now trying to work on some addition to the box. What I am missing is an information of the input signal.
As I connect it to my devices via jack I cannot hear if there is any sound going in ... I can only eventually feel it.
If there is a long pause on the audio file I will feel nothing and think that the signal may be to low, turn the potentiometer up more and then the signal starts up ... and that hurts.

I am planning to connect a bargraph to each channel - left and right - of the pre-amplifier - I have an old circuit I used on my old guitar amplifier using an LM3915. This way I can keep the potentiometer down and see if there is any input signal on the preamplifier.

Attached an example of bargraph

Let me know if anybody has done this before and if this is a good idea. Im oper to suggestions.

[Rooktus]

I am not sure how would bargraph help you. I think you will see bargraph changing and pain almost at the same time. What would help you is some kind of current limiting circuit. With this circuit you can limit max current, so you cant go over your pain threshold no matter the gain.

PS. I think design is way off. You have very big components designed for way too high power. For example resistors, transformators and amplifier are made for 20+ W.

[19Hellothere83]

I am not sure how would bargraph help you. I think you will see bargraph changing and pain almost at the same time. What would help you is some kind of current limiting circuit. With this circuit you can limit max current, so you cant go over your pain threshold no matter the gain.

PS. I think design is way off. You have very big components designed for way too high power. For example resistors, transformators and amplifier are made for 20+ W.

The picture is for reference.
The bargraph is connected to the input signal wich is not powerful.
It helps as i can see if there is an inputsinal before turning up the Potentiometer and actually feeling pain. Also if i set the bargraph to the right level i know approximateoy the input powerofthe signal.

[19Hellothere83]

I am not sure how would bargraph help you. I think you will see bargraph changing and pain almost at the same time. What would help you is some kind of current limiting circuit. With this circuit you can limit max current, so you cant go over your pain threshold no matter the gain.

PS. I think design is way off. You have very big components designed for way too high power. For example resistors, transformators and amplifier are made for 20+ W.

However I also were thingking of a way to set a max output power ... Something like a varistor peak limiter or a z- diode ... But that would be a fixed limitation ... Nice would be something adjustable ....

[Rooktus]

I am not sure how would bargraph help you. I think you will see bargraph changing and pain almost at the same time. What would help you is some kind of current limiting circuit. With this circuit you can limit max current, so you cant go over your pain threshold no matter the gain.

PS. I think design is way off. You have very big components designed for way too high power. For example resistors, transformators and amplifier are made for 20+ W.

The picture is for reference.
The bargraph is connected to the input signal wich is not powerful.
It helps as i can see if there is an inputsinal before turning up the Potentiometer and actually feeling pain. Also if i set the bargraph to the right level i know approximateoy the input powerofthe signal.

It would easier to output some test signal from PC and then set your gain to limit output power. For example 1 kHz sine at full volume.

[Rooktus]

I am not sure how would bargraph help you. I think you will see bargraph changing and pain almost at the same time. What would help you is some kind of current limiting circuit. With this circuit you can limit max current, so you cant go over your pain threshold no matter the gain.

PS. I think design is way off. You have very big components designed for way too high power. For example resistors, transformators and amplifier are made for 20+ W.

However I also were thingking of a way to set a max output power ... Something like a varistor peak limiter or a z- diode ... But that would be a fixed limitation ... Nice would be something adjustable ....

You want something to limit current not voltage as contact resistance can change a lot (maybe not that much a problem with that power resistor in series with electrodes, but still). There are a lot of different option for making current limiting circuits and most use resistor to select current.

I think the base problem of this design is using speaker amplifier because they are designed for nice constant load (4 ohm, 8 ohm, etc) and they output voltage. It would be better to use voltage to current amplifier first and then transformers. This would make control of device much simpler. Only problem is that you cant buy ready made product as this is more niche application.

[19Hellothere83]

I am not sure how would bargraph help you. I think you will see bargraph changing and pain almost at the same time. What would help you is some kind of current limiting circuit. With this circuit you can limit max current, so you cant go over your pain threshold no matter the gain.

PS. I think design is way off. You have very big components designed for way too high power. For example resistors, transformators and amplifier are made for 20+ W.

The picture is for reference.
The bargraph is connected to the input signal wich is not powerful.
It helps as i can see if there is an inputsinal before turning up the Potentiometer and actually feeling pain. Also if i set the bargraph to the right level i know approximateoy the input powerofthe signal.

It would easier to output some test signal from PC and then set your gain to limit output power. For example 1 kHz sine at full volume.

Is there any free program to check audiofile waveforms and especially amplitudes before running it through the device?
As well as is there any good software to make your own audiofiles? I wrote to the guys from estim audio as it lloks like they have some cool programs and i wanted to buy it ... But they never responded

[19Hellothere83]

I am not sure how would bargraph help you. I think you will see bargraph changing and pain almost at the same time. What would help you is some kind of current limiting circuit. With this circuit you can limit max current, so you cant go over your pain threshold no matter the gain.

PS. I think design is way off. You have very big components designed for way too high power. For example resistors, transformators and amplifier are made for 20+ W.

However I also were thingking of a way to set a max output power ... Something like a varistor peak limiter or a z- diode ... But that would be a fixed limitation ... Nice would be something adjustable ....

You want something to limit current not voltage as contact resistance can change a lot (maybe not that much a problem with that power resistor in series with electrodes, but still). There are a lot of different option for making current limiting circuits and most use resistor to select current.

I think the base problem of this design is using speaker amplifier because they are designed for nice constant load (4 ohm, 8 ohm, etc) and they output voltage. It would be better to use voltage to current amplifier first and then transformers. This would make control of device much simpler. Only problem is that you cant buy ready made product as this is more niche application.

That is true a current limiter would be better ... But concerning U-I Amplifiers ... I have no experience with that kind of Equipment...

[Rooktus]

Sure there is a lot of them. I used Audacity (https://www.audacityteam.org/) in the past. I think you can also generate some basic waveforms with it.

[Electro]

The picture is for reference.
The bargraph is connected to the input signal wich is not powerful.
It helps as i can see if there is an inputsinal before turning up the Potentiometer and actually feeling pain. Also if i set the bargraph to the right level i know approximateoy the input powerofthe signal.

It would easier to output some test signal from PC and then set your gain to limit output power. For example 1 kHz sine at full volume.

Is there any free program to check audiofile waveforms and especially amplitudes before running it through the device?
As well as is there any good software to make your own audiofiles? I wrote to the guys from estim audio as it lloks like they have some cool programs and i wanted to buy it ... But they never responded

Which "estim audio"? If it's the one from YouTube with the gold "audio suite" or whatever, feel the sample files because they feel like garbage. ..if I'm thinking about the same thing you are talking about.

Audacity is what a bunch of people use to view the audio. I usually set my computer volume so that way the amplifier volume knob is turned most of the way up, that way if I turn it down, I'm not accidentally setting it sky high during a quiet part.

[19Hellothere83]

Sure there is a lot of them. I used Audacity (https://www.audacityteam.org/) in the past. I think you can also generate some basic waveforms with it.

Thanks Ill check it out

[19Hellothere83]

It would easier to output some test signal from PC and then set your gain to limit output power. For example 1 kHz sine at full volume.

Is there any free program to check audiofile waveforms and especially amplitudes before running it through the device?
As well as is there any good software to make your own audiofiles? I wrote to the guys from estim audio as it lloks like they have some cool programs and i wanted to buy it ... But they never responded

Which "estim audio"? If it's the one from YouTube with the gold "audio suite" or whatever, feel the sample files because they feel like garbage. ..if I'm thinking about the same thing you are talking about.

Audacity is what a bunch of people use to view the audio. I usually set my computer volume so that way the amplifier volume knob is turned most of the way up, that way if I turn it down, I'm not accidentally setting it sky high during a quiet part.

So if I understand correctly you set the imput volume - which is the computers jack output volume - so low that even if you turn the estim device almost all the way up it couldnt fo damage?

[bobhill]

So finally a small update from me. I discarded the high-pass filter because it did not work and I did not have the motivation to fix it so I created a "classic" unfiltered Estim unit. The picture should describe everything needed.
The parts are already described by lolol2 in the first post. The only different part is the 3.9ohm resistor. Make sure to get a fan if you stim for longer periods.

alexfayer's Schematic:

Yes, they are, but they could easy be replaced with the connectors of your choice. I personally simplified by own design of my most recent build and bought a Nobsound amplifier that uses the TPA3116 amp chip. https://www.amazon.com/Nobsound-Channel ... 00WTOAC1M/
This saved on buying and wiring a few of the extra pieces and I just bought a 3.5mm to RCA cable. The amp is currently $33 and has a 5% "coupon" thing too. Be sure you use a 12 volt *double insulated* power supply (should have a depiction of a square inside a square). At least 3.8 amps should cover it.

So, I'm revisiting this thread and the others. Wow, there's a lot of different information and multiple tweaks to each design!

It looks like I could get these:
https://www.amazon.com/Nobsound-Channel ... 00WTOAC1M/
https://www.amazon.com/110V-220V-Conver ... B073QTNF9F
https://www.amazon.com/a12040600ux0286- ... B015Z18FXC
https://www.amazon.com/Parts-Express-Sp ... B0002KRA1U

Along with triphase switch and the trode connections and have a similar build?

Edit: The link to the transformer was not correct!