# Micro-current electrical stimulation device

#### wayneh

Joined Sep 9, 2010
17,153
Introduction
This is a project to build a micro-current electrical stimulation device. These are also called tDCS devices and are similar to MENS devices. They are not much like the common TENS devices which use much higher voltage pulses.

I have posted about this project before here. Since then I've built a couple of these devices for friends and they've been very pleased. So I thought I should update the circuit and post the complete information here.

A tDCS device provides a constant current from zero to 600µA applied the the earlobes of the user. That alone can produce a therapeutic effect, but it's more effective if
1) the current is pulsed at ~0.5Hz,
2) reverses direction (this is an AC device), and
3) the pulse timing varies "randomly".​

The changing frequency feels somewhat random and prevents a "burn in" in the patient. It's more effective than a steady beat. This is a probably a small refinement, but I wanted to include it.

#### wayneh

Joined Sep 9, 2010
17,153
The first design of this I made, I included a frequency control and also TENS capability. With usage it became clear that neither is really useful. TENS units are cheap and have lots of features, and address a completely different need. There was really no need to adjust the cranial frequency of this device because no one can be sure what setting to use. It works fine at a fixed (but varying) frequency.

#### bfrd6969

Joined Nov 27, 2016
6
that makes sense do you know the frequency range it would span through.
Is the decoupling capacitor marked 105 am I able to use a 104 interchangeable? Aldo is that a symbol for an adjustable pot on the adjustable out put and near the power supply and are they the same ?

#### bfrd6969

Joined Nov 27, 2016
6
Sorry for the redundancy i see you stated the frequency range and the 10k ohm dual gang pots thank you again im making an order on mauser as i write this.

#### wayneh

Joined Sep 9, 2010
17,153
Yes, I used all 104 ceramics in these builds. I might have used a 105 if I had one and that's why I drew that in, to remind myself to take a look. I didn't have any. I'm sure it'll be fine.

#### bfrd6969

Joined Nov 27, 2016
6
I'm having a hard time finding the decoupling capacitors as well as the 4.7 and the 47 mfd caps on Mauser what voltage rating are yours and which type if I can't find there I do have a radio shack near me I could see if they had them.

#### wayneh

Joined Sep 9, 2010
17,153

#### bfrd6969

Joined Nov 27, 2016
6
Excellent I was able to get an order of all the parts, my pcb's just arrived and all of the components from mauser will be here Monday it looks like i cant wait . I am confused as to what exactly ~4-fold range from 0.25Hz to 2hz means is 2Hz the max operating frequency, also do you by chance also have a plan for me to make your first design that i could select the frequency manually up to 100 Hz or what ever the max Hz range could be i am really interested interested different frequency's that correspond with different things like learning and lucid dreaming. Im not sure how to interpret your first diagram of your variable build but if you could make a pictogram like in this build id be willing to pay you for your time, i know i can buy one but id much rather build one. maybe with the tlv 2721 and the n556 timer Thank you anyway

#### jjb182

Joined Dec 29, 2016
4
Excellent I was able to get an order of all the parts, my pcb's just arrived and all of the components from mauser will be here Monday it looks like i cant wait . I am confused as to what exactly ~4-fold range from 0.25Hz to 2hz means is 2Hz the max operating frequency, also do you by chance also have a plan for me to make your first design that i could select the frequency manually up to 100 Hz or what ever the max Hz range could be i am really interested interested different frequency's that correspond with different things like learning and lucid dreaming. Im not sure how to interpret your first diagram of your variable build but if you could make a pictogram like in this build id be willing to pay you for your time, i know i can buy one but id much rather build one. maybe with the tlv 2721 and the n556 timer Thank you anyway

#### jjb182

Joined Dec 29, 2016
4
I'm also interested in replicating your first build with the ability to set the frequencies specifically.

I've been looking into frequency specific microcurrent machines for therapeutic uses; there is a wide range.

My brother-in-law has some fibromyalgia symptomology and I thought that I'd build one for him.

Thanks
jjb

#### wayneh

Joined Sep 9, 2010
17,153
I'm also interested in replicating your first build with the ability to set the frequencies specifically.
I recommend using the later schematic, and simply adding a pot to vary the frequency. I removed it because I don't think it matters much (at least to the users I know) but it'd be easy to add it back. If you want to hold a specific frequency, instead of the scheme I used to vary it around a central frequency, you could simplify the circuit quite a bit.

#### jjb182

Joined Dec 29, 2016
4
Hi Wayneh! I had previously been wanting to set up an Arduino to do this. If I have 5 volts on one of the pins and I turn it off and on 40 times in a second, and I pass it through my tongue, would this be similar, or provide the same effect as a FSM machine at 40 hertz?

And my other question is I would just be going from 500 microamps to 0 forty times a second... are you going from 500 to -500, or reversing the current??

Is that what FSM machines do?

I'm new and excited to explore this stuff, and (clearly) I'm a newby. Thanks!

5 Volts / 2000 ohms (average tongue resistance) --> .0025 Amps
So that's 2.5 milliamps, which is obviously over the microcurrent target, and I could throw in another resistor to bring it down to keep it below 500 microamps. (For tongue use)

For use across skin I would likely need to bring the voltage up because the resistance is so much higher...

I

#### wayneh

Joined Sep 9, 2010
17,153
Is that what FSM machines do?
What's an FSM machine?

Why do yo want stimulate your tongue?

#### jjb182

Joined Dec 29, 2016
4
What's an FSM machine?

Why do yo want stimulate your tongue?
So FSM stands for Frequency Specific Microcurrent - Machine.

And I was using the tongue as an example because the resistances just about everywhere else are so high I'd need to boost the voltage first to produce even microcurrent; I think. Also, there is an amazing book called The Brain's Way of Healing where they use microcurrent stimulation on the tongue to cause the brain to self correct after traumatic brain injuries, stroke, parkinsons, and all sorts of movement disorders.

Is it possible to send private messages here? My posts are still being moderated, and I'd love to respond to you more quickly, but it will likely take a bit before they go live in the thread.