Just for Fun: tDCS in a Bottle

If you have been reading my blog, you know that I have built a number of tDCS devices – from the simple to the complex. All do basically the same thing – deliver a very low current for the purpose of various tDCS treatments. I mentioned in my last post that Keith Spaulding of http://dcstim.blogspot.com has come up with what must be the simple tDCS design of the decade. It works, too! Keith plans to market a line of tDCS devices and I’ll review his first in my next post.

I decided to borrow Keith’s design one more time and build a simple tDCS device into an old pill bottle, just to show how easy it is to build a current regulated tDCS device – and to show how small they can be. My latest creation could easily be carried in a pocket or tucked in a hat. I call it “tDCS in a Bottle” and yes – I decided to copyright the name – hey why not?


My simple circuit consists of a type 23A 12v volt battery, a 2.2 k Ohm resistor, a current regulating diode (CRD), a pill bottle, and some lead wires. You could build one yourself in 15 minutes or less!


(Wired and tested tDCS components ready to stuff in a pill bottle. Yes, I did peel the old labels off of the bottle.)


(Closed up, ready for new labels. Small, very portable, works!)

After I completed construction, I checked regulated current output with a DVM – and plan to do so periodically to verify battery condition.

It’s sort of an ironic twist to build a tDCS device into a pill bottle – just think how many people might be able to get off of pills if tDCS were in wide use by the medical community! Wow! Anyway – “tDCS in a Bottle” works and works well – delivering a current regulated 1, 1.5, or 2 mA depending on which CRD is used.

If anyone is interested in partnering to sell these at the check-out at Walmart, let me know. We could do the country a lot of good! Pharma would not be happy. Think the FDA would be ok with it? 🙂

Disclaimer: As always, your use of any information posted here is at your risk.


A Very Simple Current Regulated tDCS Device

Simple tDCS

The Holy Grail of tDCS seems to be availability of a very simple, current regulated device that is easy to build and use.  Keith Spaulding of http://dcstim.blogspot.com got us about as close as we are likely to get with this design:


I decided to use Keith’s design, with some minor variations, and build a tDCS device.  Keith’s tDCS design is based on using a current regulating diode (CRD).  CRD’s are available in many variations including three values that are of particular interest to DIY tDCS.  They are 1 mA, 1.5 mA, and 2 mA.  You pick the value you desire, build Keith’s circuit and away you go – current limited tDCS.  Here are some plus and minus items to consider:


  1. Very simple to build
  2. Current limited by resistor if CRD shorts in failure


  1. Current is fixed – you can’t ramp it up or down.
  2. You may see a phosphene at start or end of tDCS session
  3. Keith’s design does not include a meter to confirm current level

I decided to make the following changes to Keith’s design:

1. Use a single type 23A 12 volt battery instead of two 9 volt batteries. This limits CRD failure current to 12 / 2200 = 5.5  mA instead of 8.2 mA in Keith’s design. Neither is dangerous according to studies published on the web. Both would be very irritating and immediately noticable to a user! I do use a 9 volt battery to power the display (below). You can expect 3-6 months of battery life from the type 25a tDCS battery and a year or more from the 9 volt display battery given regular use.
2. Added a digital mA panel meter so that actual current delivered can be monitored
3. Added a DPST switch to act as an on-off switch for the tDCS circuit and on-off for a separate battery and resistor to power the meter.  The digital meter I purchased needs 5 volts to operate. I use a 9 volt battery with a 1 k Ohm resistor in series to achieve the desired operating voltage.

Before I built a “permanent” CRD tDCS device, I built a test unit using a breadboard.


The type 23A battery is at the left side of the pic, the leads that go to the sponge electrodes are at the right.  Follow the red lead from the battery and you will see the CRD. It’s tiny! In the breadboard example I used two 1 k Ohm resistors (what I had handy), one in series with the plus lead of the battery and one in series with the negative lead (instead of a single 2 k Ohm resistor in series with the plus lead.  Either method is fine.)  I also threw in a 100 uF capacitor (the blue cylinder) across the leads to the sponges to ease start-up and shut-down current.  I did away with it in the final build – it didn’t seem that helpful.


Close-up of the CRD.  Note the black band is away from the plus of the battery. I decided to use a 1.5 mA CRD.  Why?  Studies posted on the web show that 2 mA is better than 1 mA for treatment effectiveness.  However, it is my experience that 2 mA irritates the skin of many individuals causing them to cease using tDCS.  As odd as it seems, backing the current off to 1.5 mA reduces reports of irritation to almost zero.

For the final build, I used a RS project box I had on hand.  You could build a CRD based tDCS device into something much smaller and more attractive.


In the bottom left is the digital mA meter circuit. To its right is a DPST switch. The left portion of the switch is used as on-off for the meter.  A 1 k Ohm resistor is in series with a 9 volt battery and the switch to provide the 5 volts needed by the meter.  The right portion of the switch is the on-off connecting the 12 volt type 23a battery to the series connected 2.2 k Ohm resistor, the CRD and the electrodes. You can see the CRD at top-center of the pic, just before I placed heat-shrink tubing over it to protect it.


Wires dressed, ready to close up the box.


Completed unit with electrodes attached shows it’s regulated current level, 1.5 mA.

So Where Do the Parts Come From?

The case, switch, resistor, battery clips, heat-shrink tubing, and leads all come from Radio Shack. The CRD came from www.mouser.com. I used PN 954-E-152, a 1.5 mA CRD with axial leads.  Be careful not to buy a surface-mount device unless you are well prepared to deal with one. The “3 digit Mini Blue LED DC 100mA meter” came from “Coldfusionx” via EBay.  They are in California – not China – so delivery was quick. I use Amrex electrodes which are available via Amazon and other suppliers.

By the way, I found the meter, as delivered, to be slightly out of calibration (it read too high).  I was able to check and recalibrate  it (adjustment screw) against a couple of DVMs.

Total cost for this project was about $50.


Keith’s design is as simple as it gets.  If you want more flexible current control, you could add a selector switch and CRDs of different values – or you could use one of the many LM device designs on the web and build a tDCS device with fully variable control.  Either way, tDCS is an amazing and wonderful thing.  Please proceed with caution and read all that you can before attempting to build your own device – especially read safety related articles and papers!  Best of all would be for you to seek out a medical professional like www.transcranialbrainstimulation.com .


The information presented in this article represents an accumulation sourced from articles, papers, popular press, and other sources easily accessed on the internet. While evidence so far indicates that tDCS is very safe, your use of information in this article is completely at your risk. You are  advised to seek out a trained medical professional for assistance with tDCS.

The tDCS “Cat” is Out of the Bag

Miracle Medication

Aspirin is a miracle medication. Isolated by Hoffman in 1897, it is a simple compound that, these days, can be created by anyone who has had a high-school chemistry course. Aspirin can, of course, be purchased in commercial form and most people are familiar with certain maladies that can be treated by it. On the fringes, there are esoteric uses for aspirin, but in the main, it is well understood and used by millions of people every day.


What about transcranial direct current stimulation (tDCS)? It’s simpler and (apparently) safer than aspirin – when used correctly – and is effective in treating depression, chronic pain, enhancing learning and much more in otherwise healthy people. So why can’t the average person on the street buy a tDCS device and self-administer treatment?



There are at least three reasons. First, tDCS is relatively new and studies that confirm its effectiveness and safety are just emerging. Two, certain tDCS treatment scenarios can be pretty complex, well beyond the ability of an average person to carry out. Third, there is no way for big-pharma to cash in on tDCS (yet). It’s very unlikely you will ever see expensive commercials during your favorite TV show advertising tDCS to treat some focus-group tested three-letter malady. It won’t happen. tDCS devices are extremely simple to build (or buy) and treatment protocols for certain ailments ARE simple and are all over the internet.

The average Joe will learn about tDCS and start demanding access to it because a bunch of do-it-yourself (DIY) folks and a few physicians will have succeeded in a grass-roots effort to get the word out. Yes, there is also a small and growing group of doctors that see the obvious benefits of tDCS (and lack of risk) and are starting to use it with their patients – and their patients are becoming some of the best spokes-persons for tDCS.

Problems, Problems

According to the CDC, about 1 in 10 adults in the US uses some form of antidepressant.  Their depression may or may not be well controlled and they likely suffer at least some noticeable side effects. Sources vary, but about $3 billion is spent on antidepressants every year. These numbers do not reflect a significant number of individuals who ARE depressed but not receiving any treatment – due to costs, social pressures, etc.

It’s hard to believe, but various sources report that as many as 1 in 3 Americans suffer from chronic pain.  Cost? $500-600 billion per year!

The tDCS Triad

Transcranial Direct Current Stimulation has been shown to provide relief for depression and chronic pain, and to enhance learning (the tDCS triad) – and much more. When treating the “triad”, it is simple, apparently very safe, and has no significant side effects. Can similar claims be made for any other other treatment (medication)?

Does it work for everyone? The simple answer is no, but for many it does – and for many who failed to get relief (or enhancement) from medications.

tDCS is not just about depression, chronic pain, and learning enhancement. As mentioned above, there are very broad areas of research seeking potential use in treating Alzheimers, stroke, brain trauma, etc. Treatment for those less understood ailments can be quite complex and require MRI or FMRI to design an appropriate regimen and the use of “high definition” tDCS, using ten electrodes or more, as part of the treatment. This is well beyond the ability of the DIY community.

But the “triad” (depression, chronic pain, learning enhancement) is normally treated with simple “bipolar tDCS” – two electrodes are placed in very specific locations on the scalp, which are well known, as part of normal treatment.

Because bi-polar tDCS involves such simple equipment and procedures, a rather sizable “do-it-yourself” community has taken up the mantle of treating themselves and helping friends reap the benefits of tDCS.

DIY tDCS is growing because most doctors have no idea what tDCS is – or what it can do. Further, doctors who do use tDCS cannot bill insurance for tDCS treatments (it is not yet “recognized” by the FDA.) So treatment can be expensive – out of reach for many – and simply unavailable in most areas of the US. So it seems that the DIY community will continue to build tDCS devices, use tDCS to treat the “triad”, and spread the word via emails and blogs. Meanwhile, research centers, Universities, and the like will continue their work on all areas of tDCS using their more sophisticated equipment and techniques to push the boundaries of tDCS application.

tDCS for Everyone?

One day, tDCS may be as commonly used as aspirin for treating certain issues – but we have a long, long way to go to get to that point. Like aspirin, tDCS won’t help everyone – but scientific and anecdotal evidence says it can help many. So while we wait, millions go untreated (or poorly-treated) and live lesser lives due to lack of access to tDCS triad treatments and all the benefits they can bring. Come on medical community, come on FDA.

Very Interesting tDCS Design

I ran into a design for a very simple tDCS device via the http://www.diytdcs.com blog.  It’s by Keith Spaulding and uses a current regulating diode rather that a current regulating IC.  I’ve ordered some CRD’s and will report on building a device in the near future.  This is about as simple as a good tDCS device could get! I will add an on/off selector switch and a ramp up/down capacitor to Keith’s idea. I might also use a type 25A 12v battery just to keep things as small as possible.  Little need for a meter or other circuit complications! Here is his schematic and a link to his blog… Thank you Keith.



User-Built tDCS Research Device

I’ve been tinkering with tDCS for several months now – including doing lots of reading and building of prototype devices.  I also have a number of friends who are giving it a try.  Along the way I’ve learned a number of things that could be useful to others:

1. Read, read, read.  Lots of tDCS articles and dialog are on the web and more every day.

2. Seek professional help with tDCS if at all possible.  For example www. transcranialbrainstimulation.com

3. Safety first! Read mine and other articles about tDCS safety. http://www.speakwisdom.com/tdcs

4. The popular ActivaDose II seems to be a good device for tDCS – a bit “edgy” in its current regulation – which may be irritating to some

5. tDCS devices built around the LM334 seem to work very well and provide very smooth adjustments to current level

6. Information on treatment montages is a bit scattered, but getting better (see my doc below for a start)

In conjunction with the above, here is the schematic I use to build devices to tinker with.  There are many other designs on the web.

User Built tDCS Research Device - Brent feb 2013

(This is my favorite design.  Simple, smooth, works.)


(Almost done.  A bit more soldering…)


(Completed except for labeling. Simple, solid, reliable!)


(Digital meter in place of analog.)


(Same basic design, just digital mA meter.)

And finally, here is a link to a bit of doc I’ve written for use with the home-built tDCS research device and ActivaDose II.


Comments and suggestions are welcome.

tDCS – Building Research tDCS Units

Just to see how easily it could be done, I built a couple of tDCS units for about $30 each using common parts. The meters were purchased from EBay for about $7 each and all the remaining components came from a local Radio Shack, including the case, voltage regulator, resistors, etc. The tDCS units feature a potentiometer to make it possible to adjust current for treatment specifics or pad variations.

(Two tDCS units built in about 3 hours for well less than $100)

(This view show the small circuit board with its voltage regulator, fixed resistor, 5k potentiometer, etc.)

I used the circuit that appears at http://brmlab.cz/project/brain_hacking/tdcs and other tDCS related web sites. I changed the circuit by eliminating the LED indicator light and switch and adding a 3 mA meter and variable resistor. I found that a fixed 150 Ohm resistor in series with a 5 k Ohm potentiometer seems to work best.

CAUTION: There is concern on the web that the LM317 regulator used in the brmlab.cz design may not be “stable” at low current levels. Some have suggested that the LM334 is a better, safer, regulator choice. The “GoFlow” design uses the LM334. UPDATE: I have updated my tDCS devices to use the LM334 design. See one of my later posts or http://www.flowstateengaded.com for examples.

(From brmlab.cz)

Before attempting to build your own tDCS device, please read, read, read, about tDCS and look at my web site and others for safety precautions.

Question or comment? Email me at brent@speakwisdom.com

tDCS – Thoughts on Safety for the Amateur


According to various reports and studies that can be read on the web, tDCS has potential to help with a wide array of brain-related maladies including depression, fibromyalgia, learning disability, and much more. It has also been shown to improve comprehension, learning speed, and more, making it attractive to students and professionals. Press articles have added fuel to the fire of public awareness by discussing how simple tDCS is and potential benefits it brings with little or no risk.

(YouTube, WorldNews, etc.)

A number of enterprising individuals have taken to building their own tDCS devices – some with little or no understanding of what they are doing. Viewing a few YouTube videos and blog posts about tDCS will quickly convince one that there is an information gap that needs to be filled before someone gets hurt.

I am not recommending anyone try building their own tDCS via this post. But the fact is many people are building them and hopefully this post will clarify what tDCS systems are all about.

In this post, I want to review a few of the more popular tDCS designs that are floating around the web and comment on them with a focus on safety.

tDCS Quick Review
tDCS involves passing a very low current (typically 1 milliamp, 1 ma) through the head for 20 minutes, once per day, for 30 or 60 days. Where the current is applied and for how long is varied by the treatment effect desired (called a montage.)

There are plenty of articles about the details of tDCS treatment on the web. Start with transcranialbrainstimulation.com as a good entry point.

tDCS Device Safety
1. If at all possible, seek out a professional for tDCS treatments. Though a bit rare right now, they are out there.

2. Do not, under any circumstances, directly connect a 9 volt battery (or any other) to your head. It’s very likely that you will greatly exceed the maximum 2 mA current limit used by tDCS researchers. You could do serious harm.

3. Never plug a tDCS device into a wall electrical outlet. Low voltage battery power only!

4. Never exceed 20 minutes in a tDCS session. Again this is the limit used by most tDCS researchers. Use a timer that will turn off your tDCS device – or at least have a very loud alarm to wake you should you fall asleep during a session.

5. Always use a digital volt meter (DVM), inexpensive, available at Radio Shack, Home Depot, etc.) to monitor current being delivered by a tDCS system.

6. If you have cranial scar tissue, an implant, or other unusual medical condition, you should seek out a medical professional before you attempt to use tDCS.

Design #1 – 9 Volt Battery and Resistor (Source of design unknown – use of this design not recommended – but it helps explain how a tDCS device works.)


The key safety element in this tDCS device is a resistor. While the correct value of resistor can indeed limit current to 1 mA, this design suffers because it is not adjustable and current flow will rise throughout a 20 minute tDCS session (typically about 25%.)

Resistor Value

Here’s a little equation known to anyone who has covered electricity in a science class or elsewhere:

i=e/r That is, current (amps) is equal to voltage (volts) divided by resistance (ohms)

If you divide 9 volts by 4,700 ohms (a standard resistor value) you get about 1.9 mA. If you build the circuit above and short the leads, this is how much current will flow through the resistor.

i=e/r 9/4700 = 0.001915A or 1.9mA

(4,700 ohm resistor in series with 9 volt battery. Closed circuit.)

If you use the same circuit above and connect and press saline wetted sponges together, so current flows through the sponges, current will be about 1.5 mA (varies with sponges).

(4.7k resistor in series with a 9 volt battery, sponges touching)

In an actual tDCS session with the above setup, current drops even further to about 0.5mA due to skin, skull, etc. resistance. This is below what researchers are commonly using.

A better alternative would be to use a 1,000 ohm (1k) resister in series with each lead of the battery. When shorted, the current flow will be 9 volts /2000 ohms = 0.0045A or 4.5mA

Saline wetted sponges connected and touching will result in about 3.5mA flow (depending sponges used.)

In an actual tDCS montage, current will be in the vicinity of 1 mA (depending on patient, sponges, etc.) However, current flow must be monitored!

(Montage in progress: 9 volt battery, 1k resistor in each battery lead, saline wetted sponges)

IMPORTANT: You can expect current to rise about 25% or more during a 20 minute session – for example, from about 1mA to 1.25mA due to saline water penetration of the skin and other factors. Thus you MUST monitor with a DVM.

Design #2: Using an LM317 Voltage Regulator – from http://brmlab.cz/project/brain_hacking/tdcs DESIGN NOT RECOMMENDED… See below.

This design is widely copied and tweaked for various feature enhancements. Note that a 9 volt battery is used as the source and a widely available LM317 voltage regulator is used to control current and prevent it from rising as it did in the design above. Current setting is controlled by a resistor connected to pin 1 and 2 of the LM317.

What value to use? I suggest a FIXED resistor of about 150 ohms in series with VARIABLE resistor (called a potentiometer) with a rating of about 2k or more ohms should give you the flexibility you need to get about 1 mA during a treatment session. The fixed resistor provides an upper safety limit of about 8 mA to shorted leads.

You will need a DVM in series with the anode (positive) lead in order to verify current being delivered by the system. 1 mA is the target and once the potentiometer is adjusted to achieve it, the regulator should keep it pretty close. Watch the DVM.

CAUTION: There is concern on the web that the LM317 regulator used in the brmlab.cz design may not be “stable” at low current levels. Some have suggested that the LM334 is a better, safer, regulator choice. The “GoFlow” design (below) uses the LM334.

(The brmlab.cz design also incorporates an on/off switch and a little LED battery test circuit.)

(brmlab.cz design built from Radio Shack parts)

Design # 3: GoFlow – http://flowstateengaged.com/

The folks involved with GoFlow have an ambitious plan to release a tDCS kit to the market fairly soon. Assuming they can get it going, they probably will sell as many as they can make! They have released the schematic for their device so that anyone can build a rough equivalent.

The GoFlow design uses an LM334 regulator to maintain a constant current. Rather than use a variable resistor, the GoFlow uses four fixed resistors of different values connected to a multi-position switch. The intent is to offer treatment levels from 0.5 mA to 2.0 mA.

The only thing the GoFlow design lacks is a way to monitor the current actually entering your head. If you build your own from scratch, you can simply connect a DVM in series with the anode (positive) lead. Problem solved.

(GoFlow circuit diagram)


If you are going to build your own tDCS device, your focus should be on safety. Part of being safe is knowing what your are putting in your head! I’ve mentioned several times the importance of using a DVM – but you can also use a panel meter, available from many sources to monitor the very low current of a tDCS session.


(0-3 mA Panel Meter, about $7 on EBay)

However, a DVM is still a good and easy to obtain tool. They are commonly $20 to $50 at Radio Shack, on EBay, etc.


(Example Digital Volt Meter, DVM)

Building a tDCS device? Use your head!