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

[diglet]

Edger477 did fairly extensive research on the modern TPA3116 amps

Actually, I did not research myself, I suspected that the reason for them might have been that older amps did not pump current until they detect some minimum load, and asked about it in Joanne's discord (there are some very good electronics engineers there). On modern amps, especially with a transformer that has static resistance (when you measure with Ohmmeter) that is 4 or 8 Ohms (the side we connect to amp), these parallel resistors are just waste of power, and also source of unnecessary heat.

My mistake. Perhaps it was Diglet that did the testing?

I did some testing with a tpa3116 clone, scope and parallel resistor, was not able to identify any useful effects.

Tests available here: https://github.com/diglet48/restim/wiki ... l-resistor

[fishyfish]

All the rest of the schematic seems clear to me but can somebody clarify how to connect the triphase switch?

Below is an example where I would use the outer connectors. I suppose the correct wiring depends on the switch too? I don't know if this is right, I'm just providing the picture to make it obvious what I'm asking.

triphase.png (103.49 KiB) Viewed 3514 times

[Míchael]

All the rest of the schematic seems clear to me but can somebody clarify how to connect the triphase switch?

Below is an example where I would use the outer connectors. I suppose the correct wiring depends on the switch too? I don't know if this is right, I'm just providing the picture to make it obvious what I'm asking.

triphase.png

Thats correct for triphase you connect both "-" with the switch as seen in the schematic.

[fishyfish]

Thats correct for triphase you connect both "-" with the switch as seen in the schematic.

Thank you. I notice I got the wrong kind of a switch for this (two pins, not three) - I suppose it would also work if the only purpose of the switch is to either bridge the "L&R -" outputs or separate them?

[Míchael]

Thats correct for triphase you connect both "-" with the switch as seen in the schematic.

Thank you. I notice I got the wrong kind of a switch for this (two pins, not three) - I suppose it would also work if the only purpose of the switch is to either bridge the "L&R -" outputs or separate them?

Yeah the purpose is to simply connect the two. The 2b doesnt do it as a hardware solution for example and you could also just use a wire that shorts / connects both "-" pins.

For the switch as far as I know is the third pin (middle) common so just dont connect anything to it and it should work.

[limitsky]

Hi, I'm currently collecting the parts to make the tronic Midistim for the first time and was wondering what is a good electrode socket to purchase for 3.5mm size so I can solder it to the transformer wires. I have a 2B and want to use the 3.5mm to 2mm output cables that they gave.


Parts I plan to use were:

Transformer: Parts Express 70V 10W Speaker Line Matching Transformer

Amp: Nobsound HiFi 2.1 Channel Bluetooth 5.0 Power Amplifier Board Case Stereo Subwoofer Amp

Power: [UL Listed] Chanzon 12V 5A 60W AC DC Power Supply Adapter (Input 110V-220V, Output 12 Volt 5 Amp 60 Watt) DC Converter LED Driver Lighting Transformer for 12 V 5 A Flexible LED Tape Strip Light

Resistor: Uxcell a12040600ux0286 Chassis Mounted Aluminum Housed 25W 3.9 Ohm 5% Wirewound Resistors

[Míchael]

Hi, I'm currently collecting the parts to make the tronic Midistim for the first time and was wondering what is a good electrode socket to purchase for 3.5mm size so I can solder it to the transformer wires. I have a 2B and want to use the 3.5mm to 2mm output cables that they gave.


Parts I plan to use were:

Transformer: Parts Express 70V 10W Speaker Line Matching Transformer

Amp: Nobsound HiFi 2.1 Channel Bluetooth 5.0 Power Amplifier Board Case Stereo Subwoofer Amp

Power: [UL Listed] Chanzon 12V 5A 60W AC DC Power Supply Adapter (Input 110V-220V, Output 12 Volt 5 Amp 60 Watt) DC Converter LED Driver Lighting Transformer for 12 V 5 A Flexible LED Tape Strip Light

Resistor: Uxcell a12040600ux0286 Chassis Mounted Aluminum Housed 25W 3.9 Ohm 5% Wirewound Resistors

For my first box I used this one as audio input:
https://www.conrad.de/de/p/tru-componen ... 64526.html

Should also work fine as elektrode input.

[pess1]

Hello!
I am looking to build my own stereo stimbox.
Tho firstly i'd like an amp that is ready out-of-the-box.
I'm basically illiterate when it comes to audio tech and electricity is like magic to me
Anyhow, on reddit and some posts here i've seen there's a mix between amp with 50*2 and 100*2.
and my question is whether a 50*2 would be enough for a stim out-of-the-box, before i eventually do a build?
i have 3 different psu's
1: 12V 3A (The Handy power source, type II. Works with my 2B)
2: 19.5V 6.92A (Laptop charger)
3: 19V 6.32A (Laptop charger)

Option 2 and 3 does not have the "type II; square within a square" mark, but a "-" going to a "half circle encompassing a circle" going to a "+".
Are any of these viable, safe options?
this is the amp i'm considering
https://cdon.no/hobby-fest/zk-502c-hifi ... p149952962

[limitsky]

For my first box I used this one as audio input:
https://www.conrad.de/de/p/tru-componen ... 64526.html

Should also work fine as elektrode input.

Thanks for the link! Following the midistim schematic, it says one jack would be L+ and one jack would be L-, same for right channel. If I'm using those sockets for electrode input, do I solder the L+ onto left channel and L- to ground? Or would both L+ and L- go to the LEFT channel on the socket?

I'm imagining it like the 2B electrode jacks where I just plug in one 3.5mm jack for one channel and connect the electrodes, so I would only need 2 of these sockets (one for channel A and B) instead of 4?

[Míchael]

For my first box I used this one as audio input:
https://www.conrad.de/de/p/tru-componen ... 64526.html

Should also work fine as elektrode input.

Thanks for the link! Following the midistim schematic, it says one jack would be L+ and one jack would be L-, same for right channel. If I'm using those sockets for electrode input, do I solder the L+ onto left channel and L- to ground? Or would both L+ and L- go to the LEFT channel on the socket?

That is up to you I would say. The socket has as you noticed 3 connections (left, right, ground) and you need only two (left+ and left-). You can ignore the ground or just connect it with the lower connector.

I'm imagining it like the 2B electrode jacks where I just plug in one 3.5mm jack for one channel and connect the electrodes, so I would only need 2 of these sockets (one for channel A and B) instead of 4?

That is correct if you do it like this you only need 2 ports instead of 4.

Hello!
I am looking to build my own stereo stimbox.
Tho firstly i'd like an amp that is ready out-of-the-box.
I'm basically illiterate when it comes to audio tech and electricity is like magic to me
Anyhow, on reddit and some posts here i've seen there's a mix between amp with 50*2 and 100*2.
and my question is whether a 50*2 would be enough for a stim out-of-the-box, before i eventually do a build?
i have 3 different psu's
1: 12V 3A (The Handy power source, type II. Works with my 2B)
2: 19.5V 6.92A (Laptop charger)
3: 19V 6.32A (Laptop charger)

Option 2 and 3 does not have the "type II; square within a square" mark, but a "-" going to a "half circle encompassing a circle" going to a "+".
Are any of these viable, safe options?
this is the amp i'm considering
https://cdon.no/hobby-fest/zk-502c-hifi ... p149952962

In regards to the amp. Most amps have two run options. 12V and 24V and all builds i have seen are usually running with 12V and 50W per channel from the ampside. 50W per channel are plenty enough to do stimming with. We want a very low current and and a high voltage.

For the PSU. You can use the first option. Dont use #2 and #3 if they dont have the typeII symbol!. However #1 could be too weak. The usual suggestion is to go for 5 or 6 Amp PSU. Im using a 5A 60W psu. You have to remember that you power 2 channels with the psu so you have roughly 1.5 Amps per channel. You can try it for sure but maybe you need more power.

[pess1]

Thank you for your response and insight. I will give it a shot then reiterate and upgrade as needed!

[Xiphid]

I've just finished my first device based on lolol2 v2 (messy but works!)

Estim.jpg (152.37 KiB) Viewed 765 times

I'm having issues with my right channel being about 1/4 of the power of my left channel. I've checked with the meter and at the board with a file playing I'm getting 1.5 on the right and 5.6 on the left. I've checked the resistances, the pots, my connections and everything seems okay, but I have to admit my electrical knowledge is limited.

Can anyone provide suggestions what I should check to find out what's wrong or what could be causing this?

I also get a small electrical signal when I turn on the machine (even if the file isn't playing when the switch gets turned on I get a pulse and it's not always the same strength), would this be some sort of grounding issues?

Thanks

[tommarr]

Finally updated my wire mess which was quite similar to viewtopic.php?t=23322. Biggest issue was it was just a mess to get and start using and store away

Ordered bahar case because it looked nice and built everything into it

Spoiler: show

Much better now And I kinda like the case

Still need to test try that how does it run and I'm a bit mad that I accidentally ordered momentary ON-OFF-ON switch for swapping channel. Figured it would be nice to have option to switch channels but no can do. Maybe I'll get correct switch later

[lolol2]

I'm having issues with my right channel being about 1/4 of the power of my left channel.

It looks like the pods on the amp are in different positions?
The small white round things next to the 3 pin connector input.
Those should be in a straight line matching the pin connector like shown in the picture of the connection plan.

I also get a small electrical signal when I turn on the machine (even if the file isn't playing when the switch gets turned on I get a pulse and it's not always the same strength), would this be some sort of grounding issues?

For that add a 3 channel switch like mentioned in my design.
Some AMPs are "noisy" when they loose power, that is normal.

2) I have routed the output over the power switch for both channels, this prevent to have any not wanted AMP noices which can appear when you turn of the power. This is more a safty feature I wanted to have, when you switch off the device, you also cut you off from the electrodes. I have experienced this with the listed AMP, so I would recommend to add this switch.

Otherwise your box looks really nice, totally fine with the cabeling, this should do the job!

[tommarr]

I also get a small electrical signal when I turn on the machine (even if the file isn't playing when the switch gets turned on I get a pulse and it's not always the same strength), would this be some sort of grounding issues?

For that add a 3 channel switch like mentioned in my design.
Some AMPs are "noisy" when they loose power, that is normal.

I'm also having this spike with the freshly built unit which already implements this 3-channel switch to connect/disconnect right/left channel with power. This is happening when turning on, not when turning off. I was also checking the amps and they do spike when powered on quite high compared to normal usage. Not sure where that is coming from. My build is also based on lolol2

I'm just having crappy 5 dollar multimeter at home which is really slow and not a scope so can't really see clearly what happens at outputs just after turning the power and connecting channels