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

[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!

[Electro]

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!

These components would make a similar build to the Tronics Midistim design. That's the same resistor, amplifier, transformer(multiple options were in the specification, I personally used a Specco T7010 but the parts express looks like a suitable lower cost option that was in the specifications, and the power supply that was in the spec on the Smartstim website, however it appears the amp changed but it still uses the reliable TPA3116 amplifier chip according to the ad and I figure it is still probably just as suitable as long as the amp chip still has a heat sink. The link below is the one with some cheaper components. That amplifier has been used by a number of people here with success, it's a bare board instead of a cased amplifier, but if you are comfortable or already planning to build your estim device into a case you find, that seems to be a reasonable option.
viewtopic.php?f=12&t=23322

I've said it in other places, but I will continue to say it here too, you want to be sure you are getting a double insulated(square inside a square symbol on the power supply) ungrounded(2 prong plug) power supply otherwise you risk getting shocked by your house power if you touch anything that might expose you to a path to ground(metal appliance that's grounded for example). The one linked in the other thread is an example of one that would be unsafe according to the long conversations about this at smartstim before the site went down.

[bobhill]

These components would make a similar build to the Tronics Midistim design. That's the same resistor, amplifier, transformer(multiple options were in the specification, I personally used a Specco T7010 but the parts express looks like a suitable lower cost option that was in the specifications, and the power supply that was in the spec on the Smartstim website, however it appears the amp changed but it still uses the reliable TPA3116 amplifier chip according to the ad and I figure it is still probably just as suitable as long as the amp chip still has a heat sink. The link below is the one with some cheaper components. That amplifier has been used by a number of people here with success, it's a bare board instead of a cased amplifier, but if you are comfortable or already planning to build your estim device into a case you find, that seems to be a reasonable option.
viewtopic.php?f=12&t=23322

I've said it in other places, but I will continue to say it here too, you want to be sure you are getting a double insulated(square inside a square symbol on the power supply) ungrounded(2 prong plug) power supply otherwise you risk getting shocked by your house power if you touch anything that might expose you to a path to ground(metal appliance that's grounded for example). The one linked in the other thread is an example of one that would be unsafe according to the long conversations about this at smartstim before the site went down.

Thanks for the feedback, I really appreciate it! That power supply is from a link that you supplied, so I thought it should meet the requirements.

I am going through the build on the other thread, the Nobosound amp was from another link that you posted in this thread.

I'm fine with using the Specco's if you think they may be a better fit with these components (particularly the resistors). I also don't know if there's a material difference between this design and the one in the other thread. I settled on the components above based upon recommendations, not because I have any insight - and I'm fine with spending a bit more for a better result!

[Electro]

Thanks for the feedback, I really appreciate it! That power supply is from a link that you supplied, so I thought it should meet the requirements.

I am going through the build on the other thread, the Nobosound amp was from another link that you posted in this thread.

I'm fine with using the Specco's if you think they may be a better fit with these components (particularly the resistors). I also don't know if there's a material difference between this design and the one in the other thread. I settled on the components above based upon recommendations, not because I have any insight - and I'm fine with spending a bit more for a better result!

The Nobsound amp when I linked it looked different, not sure if it's purely a cosmetic change though, but it says it uses the same amp chips, so it probably is as good as being the same.
The Specco versus the ones you linked should be similar enough to not make a difference, I would have probably bought those Parts Express ones myself, but at the time I bought the components for my most recent build, the only option on Amazon was the Specco T7010 transformers. Since they are mutli tap 70v or 100v transformers with turn ratios that are suitable for how we are using them, I expect either of those should produce a result that would probably not have any noticeable difference.

[basquiat]

I've said it in other places, but I will continue to say it here too, you want to be sure you are getting a double insulated(square inside a square symbol on the power supply) ungrounded(2 prong plug) power supply otherwise you risk getting shocked by your house power if you touch anything that might expose you to a path to ground(metal appliance that's grounded for example). The one linked in the other thread is an example of one that would be unsafe according to the long conversations about this at smartstim before the site went down.

Hi there.. So I built the parts express version from the other thread and have been using it quite happily for a few months. Your quote there really got me concerned now, if someone was just lying in bed enjoying a sesh would there be much danger? Is there any tips to better insure not getting shocked besides the obvious dont touch appliances or anything metal and grounded? Curious how concerned i should be.

Also what would the equivalent U.S. version of that power supply be and could it power the board from the U.S. build? Appreciate any info.

[lolol2]

Just make sure that your power supply has this sign (square inside a square) which is the indicator for a double insulated one and it's save to use. Should also available in US or do they have another sign for that, maybe someone from US can help?

I's not important where you play, in bed or somewhere else... always use a double insulated one.

I have added this to the first post too.

[Electro]

I'm in the US, this power supply is the one I bought. It's the same one recommended by the Smartstim folks for their build and it's only $15.99

https://www.amazon.com/110V-220V-Conver ... B073QTNF9F