Electrode Wars! (Well Not Quite)


I’ve written a ton about all the great potential of brain stimulation and particularly tDCS. There are many studies and plenty of anecdote related to improving memory and creativity, reducing chronic pain, treating depression, etc. More about all of that later.

The National Center for Health Statistics just announced that the U.S. suicide rate has climbed to a 30-year high. This coupled with data that we have long had in hand – about 10% of the U.S. population is clinically depressed, that there are about 40,000 suicides in the U.S. every year, and that only about 20% of the people needing depression related treatment actually get it – tells you that our national mental health system is a failure.

tDCS* has emerged as a treatment method that is inexpensive, simple, safe, and has good effect for many of those who use it for depression related symptoms. tDCS use by professionals continues to grow and certainly the do-it-yourself (DIY) community is enthusiastic about it. tDCS requires placing electrodes on the head and passing a very tiny current between them in order to nudge the brain towards proper functioning (or enhancement.)

There are two popular kinds of electrodes, stick-on and sponge. Stick-on electrodes are simple and very useful when hair won’t get in the way. They are used once (or a few times for some) and discarded.  Sponge electrodes are preferred by most using tDCS as it can be used on skin or over hair, can be reused many times, and has a low cost per use.

Amrex has been the big dog in sponge electrodes for the tDCS world for a long time but competitors are emerging and I’d like to cover two of them here. First, Caputron (www.caputron.com) introduced a nice “clone” of the Amrex electrode some time ago and continues to offer it today.  It is available as a 3×3 (typical size used in tDCS) or 2×2 shell (about 2×2 and 1.1 x 1.1 sponge contact dimension). The Caputron electrode does have two distinct advantages – first they are more flexible and conform to curves of the skull more easily, and second they are much less expensive! A 3×3 electrode is only $12! They, like the Amrex electrodes have a banana jack for connection and a stainless steel screen behind the sponge for even current distribution. Also like Amrex electrodes, you can buy replacement sponges from Caputron (about $1 each) – or make your own from kitchen sponges.

(The Caputron shell – orange – with the sponge removed. Note the stainless screen and banana jack. An Amrex shell is shown too – gray.)

Caputron also offers a nice, general purpose strap system that can be used with any brand of sponge electrodes. It’s called the Caputron Universal Strap System and is made of rubber (not latex). There are two independent straps that are marked with a centimeter scale that makes accurate placement of electrodes easy. The system is stretchy and very adjustable for position and head size. I really like this strap system and you will too – if you don’t mind the $75 price.

(The Caputron Universal Strap on my much abused “test head”. The strap is versatile and easy to use.)

foc.us (famous for the foc.us V2 brain stimulation device and the new Go Flow tDCS device) is just releasing a new sponge electrode system  for the V2 and Go Flow that is very interesting! It consists of a rubber-like shell (about 2×2) and sponges that when inserted result in a 1.25 x 1.25 inch sponge contact area. To connect to the foc.us sponge electrodes, you need a special V2/Go Flow cable that attaches magnetically to the electrode shell. That means the problem of having an electrode jerked off of your head should you become tangled somehow goes away. This is a vastly better connection technology than the banana plug and socket used by many manufactures.

(The new foc.us electrode shell and sponge. Note the magnetic ends on the wires for easy attachment to the electrode shells. A new production white Go Flow and 9 volt battery are also shown.)

foc.us is also releasing a companion head strap with strategically placed cutouts that allows easy and repeatable placement of the electrodes on your head. This new strap ships as part of the “Go Flow Pro” which includes the tDCS device, wires, strap, electrode shells (and sponges) and will be available for separate purchase too.

(The new electrode shells, strap, and Go Flow with battery. Note: some electrode setups may require two straps.)

All of the items mentioned in this blog post (including Amrex and foc.us) can be purchased from Caputron (www.caputron.com).  It’s great to have a dealer here in the U.S. that is carrying a huge variety of devices and accessories. I suggest you visit their web site and have a look.

There are many articles about tDCS available on my blog ( www.speakwisdom.com ) and via www.diytdcs.com .

*transcranial direct current stimulation




How to Pick the Right Stuff for the Go Flow tDCS Device

(NOTE: The retail packaging and pricing of the Go Flow has changed as of mid-March 2016. See http://www.foc.us for details. This is part 2 of my series on the Go Flow. See http://www.speakwisdom.com for more.)


So you are interested in buying a foc.us Go Flow tDCS* device? What accessories should you buy – and where can you find information on electrode placements and more? In this post I’ll review your options and make some suggestions based on my experience with tDCS and the Go Flow.

Go Flow image 2
(Image from the http://www.foc.us web site.)

Decisions, Decisions – Electrodes First

Oddly, you first need to decide whether you will use sponge or stick-on electrodes in your Go Flow tDCS sessions. Visit www.tdcsplacements.com to see common tDCS electrode placement scenarios. If the one you select involves placing an electrode over hair, stick-on electrodes will not work and you will need to use sponge electrodes. Why this choice comes first will become clear now…

The Go Flow tDCS module can be purchased alone ($9.99) or in a kit including stick-on electrodes and wire. For $19.99 you can get a kit that includes standard hydro-gel stick-on pads or for $29.99 you can get the kit with “Pro” hydro-gel stick-on pads. See www.foc.us for details and ordering information. If you intend to use 3rd party sponge electrodes (like Amrex), you can buy either the $19.99 or $29.99 kit and modify the included cable.

Go Flow review pic 3
(This is the $29.99 kit – complete and ready to go. It includes the module, wire, electrodes, and battery. Image from the foc.us web site.)

One subtle difference in the two types of stick-on pads is the use of silver as a conductor in the “Pro” pads. It’s important to note that stick-on pads are a “consumable” and must be periodically replaced (sold on the foc.us site.) You’ll need to keep in mind shipping delays in ordering replacements. Also, as mentioned above, stick-on pads won’t work over hair – only on bare skin. I personally prefer to use sponge-type wetted electrodes. Some consider them a hassle (getting them wet, making sure they are not too wet, cleaning them, etc.) However, they can be used on skin or hair and the sponges tend to last for many tDCS sessions.

3rd Party Electrodes

The foc.us Go Flow kits come with a nice connecting cable with magnetic ends designed to connect to specific stick-on type electrodes. If you choose to go 3rd party for electrodes (sponge or otherwise), you may need a different electrode connector. For example, connecting to Amrex sponge electrodes requires a 4mm banana plug.  A simple solution is to cut the ends off of the supplied foc.us wire and put on whatever type of connectors you need. Banana plugs are widely available from Radio Shack, Amazon, Parts Express, etc.

(If you are a bit handy, you can cut the default ends off of the kit supplied Go Flow cable and attach your own ends. Here I’ve soldered banana plugs on one of my cables. Note: I fill the shell of the plug with silicon rubber to act as a strain relief.)

I’d love to see foc.us begin to sell preconfigured cables that include banana connectors and pin-type connectors for TENS electrodes (cheap and widely available.)

Going with Amrex Sponge Electrodes (instead of stick-on)

Amrex electrodes (and knock-offs) are widely available from medical supply companies (many online) and Amazon.com . I suggest purchasing the 3×3 size but other sizes are available (you will need two.) You can cut ordinary kitchen sponges to fit the Amrex shell as you need to do sponge replacement. Amrex 3×3 electrodes sell typically for $15 to $20 each depending on the supplier.

Another Cable/Adapter Option for Amrex Sponge Electrodes

If you choose to use Amrex sponge electrodes (or knock offs), you can follow the suggestion above and modify a foc.us supplied cable or purchase the following:

  1. An adapter that converts the unusual 2.5 mm 4 conductor jack of the Go Flow to a more common 3.5 mm 2 conductor jack. Source: http://www.foc.us/tdcs-tens-cable-adaptor $6 plus shipping
  2. A cable with a 3.5 mm 2 conductor plug, lead wire, and banana plugs that connect to the Amrex sponge electrodes. Source: http://www.bluemoonhealth.com/tens_supplies_pages/banana_wires.htm $7 plus shipping. This kind of cable can be ordered from a number of different suppliers.

One last possibility if you are handy with a soldering iron is to make your own cable from scratch. www.partsexpress.com is a good source for the needed 4 conductor 2.5 mm plug, banana plugs, and other needs.

Headband for Sponge Electrodes

You will need a headband to hold sponge-type electrodes in place during a tDCS session. A sweatband sold in discount and sporting goods stores will work nicely.


The foc.us Go Flow is a great tDCS device – providing great capability at a very low price. Making the proper selections for your needs is important. Remember, you need the Go Flow module, connecting wire, and electrodes (and perhaps a headband.)  The Go Flow kits are a great bargain!

Feel free to post questions on this blog – or email me at brent@speakwisdom.com . What else would you like to know about tDCS by way of this blog?

If you haven’t already, please see part 1 of my series on the Go Flow at https://speakwisdom.wordpress.com/2016/01/20/the-brain-hacking-revolution-continues-introducing-the-foc-us-go-flow-part-1/

See my blog www.speakwisdom.com  for more general information on tDCS. www.diytdcs.com is also an excellent resource.

Thank you.



Anyone considering the use of tDCS or any brain stimulation technology should do their homework. It’s important to understand the technology, risks, and if you should be excluded based on seizure disorder or other complications. If you are unsure you should seek the advice of a doctor, preferably one using tDCS or similar technologies in their practice.

*tDCS is transcranial direct current stimulation

The Brain Hacking Revolution Continues: Introducing the foc.us Go Flow

( NOTE: The retail packaging and pricing of the Go Flow has changed as of mid-March 2016. See http://www.foc.us for details. This is part 1 of my series on the Go Flow. Parts 2 and 3 are also available at http://www.speakwisdom.com )

(The Go Flow in white or gray – next to a foc.us V2)


While preparing this blog post, I pondered what its title might be.  Here are a few of my ideas:

The New Price of Freedom (from Depression, Chronic Pain, and more) $9.99

New foc.us Go Flow tDCS Device Raises the Bar, AGAIN!

tDCS* for Everyone! The New foc.us Go Flow

Hey Medical Community. No More Excuses, Time To Get On Board.

…well, you get the idea. Foc.us has done it again – bringing to the world a really cool, very capable, tDCS device at a price that will rock the marketplace, $9.99. That’s right, not $999 or $99.99, but less than $10! Add electrodes and wires and you can have a top-notch tDCS kit for less than $30!

For those suffering with depression, chronic pain, and learning disabilities, the miracle of tDCS just became VERY affordable. This same device can also be used to enhance memory, problem solving ability, creativity, athletic ability, etc.  Ahh yes, tDCS is a wonderful thing.

And now, my oft repeated question for the medical and mental health community – when are you going to at least give tDCS a chance? You are more than happy to experiment on your patients with a variety of pharmaceuticals – frequently with poor results and nasty side-effects. Why not try something that provides great relief to some (honestly, not everyone) – without scary side-effects? Add up the annual cost to the patient of buying pharmaceuticals and follow-up care vs. the cost of a Go Flow, a few 9 volt batteries, and some oversight. Wow, are you beginning to get it?

If you are hearing about tDCS for the first time, please see my other related posts at www.speakwisdom.com or check out www.diytdcs.com for more of the basics on this great technology!

The foc.us Go Flow

The Go Flow tDCS device is a tiny module that snaps on to the top of a standard 9 volt battery. A pair of electrodes plug into the module using the same plug configuration that foc.us uses with their V2 product.

Some Key Features

  • Current delivery from 0.5 to 2 mA in 0.125 mA increments
  • Timed delivery from 5 to 35 minutes
  • Ramped Current up / down
  • Easy to use control switch and LED indicators
  • Tiny, light, rugged. Uses a standard 9 volt battery
  • Perfect for beginner, pro, home and travel use


Let’s say you want to treat depression with a Go Flow. What would a tDCS session with the Go Flow be like? Here are typical steps with some discussion along the way:

  1. Attach electrodes to the forehead area (anode on the high-left forehead, called F3, cathode on the right above the eyebrow, called FP2. See tdcsplacements.com for details.) You can use stick-on gel electrodes or wetted sponge electrodes. I discuss how to tell anode from cathode below.
  2. Plug electrode wire into the Go Flow unit
  3. Attach the Go Flow module to a 9 volt battery
  4. The Go Flow LEDs will light up in sequence as it powers up and leave you with one or more ORANGE LEDs lit, showing the amount of current for your session. The lowest LED represents 0.5 mA, the highest 2.0 mA. To change the current level slide the rocker switch UP for more current or DOWN for less.  A typical tDCS session is 1, 1.5, or 2 mA.Go Flow image 2
    (The Go Flow module showing LED display, electrode jack, and slide switch.)
  5. Once you have the desired session current set you PRESS IN on the rocker switch to move to the time setting.
  6. Session time is shown with GREEN LEDs with each representing 5 minutes of time. Slide the rocker switch UP for more time or down for less.  A typical tDCS session is 20 minutes.
  7. You are ready to begin your tDCS session! To START, PRESS IN on the rocker switch one more time.
  8. With a session in progress, the LED display will alternate between GREEN, showing time remaining, and ORANGE showing the actual delivered current level.

(The Go Flow connected to my “test head” using Amrex electrodes.)

Additional Notes:

  1. You can STOP your tDCS session anytime by pressing IN on the slide switch. Current will ramp down gently to zero
  2. You can adjust current level up or down during a session. Move the slide switch up or down as desired. Each movement will change the current 0.125 mA
  3. There is no ON/OFF switch on the Go Flow. When your session is complete, UNPLUG the 9 volt battery

(Wow how things have changed! Go Flow next to a DIY tDCS device I built a couple of years ago. Thank you foc.us!)

Technical Notes:

  1. I measured the current output of the two Go Flow units I have and found current to be spot on with my current selection.
  2. Maximum output voltage is 24 volts (needed to overcome electrode resistance, skin resistance, etc. This is much better than the 9 volt max of many DIY tDCS devices.
  3. Current drain on the battery is, according to my measurements, about 24 mA during a 2 mA tDCS session. It is about 13 mA for a 1 mA session.  Current drain varies somewhat depending on how many indicator LEDs are lit.
  4. A Duracell CopperTop 9 volt battery goes from 9 volts to 8 volts in 25 hours with a 10 mA load. So one could expect at least 50 to 100 tDCS sessions per battery (highly dependent on session settings.)

Go Flow inside 1
(Inside the Go Flow. Image from foc.us.)

Electrode Choices with the Go Flow

  1. foc.us has a number of electrode choices available on their web site – and third party electrodes can be used with the Go Flow, too. Foc.us supplied electrodes and cable are marked to indicate anode and cathode. Some models have a big X stamped or printed on the anode and a Y on the cathode.  With any electrodes, if you are not sure of polarity, check with a volt meter.
  2. The electrode connector in the Go Flow uses a 2.5 mm four conductor plug for its mate. From the tip of the plug (1) to base (4): 1-unused, 2-unused, 3-Y cathode, 4-X anode (which is the same as the default foc.us V2 setup.)
  3. foc.us has adapter cables and such on their web site. You can also easily build your own cables with parts from Radio-Shack, Parts Express, etc.
  4. I have a personal preference for wetted sponge-type electrodes as they can be used on skin and over hair and provide excellent conductivity.


The foc.us Go Flow represents a true shift in the brain stimulation and tDCS marketplace. Via this new product they provide all the capability a typical user will ever need – in a tiny, easy to use, convenient package.  The Go Flow, sold along with a good instructional video could literally change the lives of millions for the better. I’d love to travel around providing instructional seminars for medical and mental health professional showing them the Go Flow and that tDCS really is a miracle! Anyone willing to fund that?

The Go Flow can be ordered now at http://www.foc.us . Watch for Part 2 of my review of the Go Flow coming soon.


Anyone considering the use of tDCS or any brain stimulation technology should do their homework. It’s important to understand the technology, risks, and if you should be excluded based on seizure disorder or other complications. If you are unsure you should seek the advice of a doctor, preferably one using tDCS or similar technologies in their practice.

*tDCS is transcranial direct current stimulation


Summer is Here! Time for The Brain Stimulator Travel Model!

Travel Model Advanced 2x2 Kit - Unplugged_NEW
(The Brain Stimulator Travel Model shown with available electrodes, wires, and headband. The tDCS module itself is very small and easy to transport.)

I am a longtime fan and proponent of tDCS.  There is plenty of evidence that this simple, safe, technology can be used to reduce or eliminate depression, treat chronic pain (including migraine headaches), enhance memory and learning, and more!  If you are new to tDCS, take a look at the index of tDCS articles I’ve posted at https://speakwisdom.wordpress.com/tdcs/

If you are looking for a high quality tDCS device that also happens to be ideal for summer travel, you should consider “The Brain Stimulator Travel Model”.  This is a well-built, basic, tDCS device that can deliver 1 or 2 mA with the flick of a switch and can stand-up to being repeatedly tossed into a suit-case or travel bag, jostled around, and still come out ready to go and deliver a reliable tDCS session.  Depending on the configuration you buy, it can cost as little as $55 – or a bit more with high quality electrodes and other accessories.

The Brain Stimulator Travel Model also makes an excellent first tDCS device or a supplemental device if you already own something more sophisticated.  It is built by JD Leadam and his team at Neurolectrics – real pioneers in the DIY tDCS marketplace.


(The packaging of the devices is simple, neat, and able to withstand travel related abuse.)

Neurolectics used a tried and true design built around a current regulator and a 9 volt battery. It’s simple, safe, and reliable – but because a 9 volt battery is used as its energy source, it is very important that sponge-electrodes be used and that they be well wetted with a saline solution in order to assure delivery of 1 or 2 mA (depending on switch setting).

I always prefer that a DIY tDCS device have some monitoring capability (digital or analog meter) to assure that the desired current level is being delivered. Neurolectrics chose not to take that path with this device – I assume to keep cost at a minimum and the package as small as possible.  If you are a frequent tDCS user, I’d suggest changing the 9 volt battery every couple of months – and again – be sure to use well wetted sponge electrodes to help assure you receive the selected stimulation level.

(Neurolectrics places all significant components on a nicely manufactured PC board. This limits point-to-point wiring and makes for a more reliable device – important for a travel device.)

The Brain Stimulator Travel Model could not be easier to use!  Simply wet the electrode sponges, place the electrodes as desired with a headband, flip the switch to 1 or 2 mA, and begin timing your tDCS session (20 to 25 minutes is typical.) When done, switch off the device, take off and stow the electrodes and you are done.  If you really are traveling with the device, I suggest you remove the sponges from the electrode shells and place them in a small water-tight container.  You should also wash them frequently with good soap and plenty of water to prevent anything undesirable from growing in them!

I’ve taken several trips (including through airports and airport security) with the The Brain Stimulator Travel Model and found it to be quite handy for personal use and for demonstrating tDCS as seminars.  Don’t expect any flashing lights or fancy meter with this unit.  It’s basic tDCS – and it works.

Visit the Neurolectics website at https://thebrainstimulator.net/

I welcome your comments and questions.




Why I Love tDCS and the New tDCS Device from SSD

Introduction: Why I Love tDCS

I’ve been involved with transcranial direct current stimulation (tDCS) research and application for almost three years now.  When I stumbled upon it, I could not believe (like most of you) that something so simple could do so much good. A 9-volt battery curing depression, relieving chronic pain, improving memory, speeding learning, and much more – really?!  It turns out to be true.

(The new SSD tDCS Device. see below)

I’ve provided information on tDCS to dozens of people (thousands via my blog) with an array of needs and interests who have had great success helping themselves improve their lives through tDCS.  I could provide many examples, but here is one to illustrate my point:

A woman, (friend of the family), came to me describing deep, debilitating depression – to the point of becoming suicidal. Normally I would immediately refer such a person to Dr. James Fugedy, a tDCS practitioner in Atlanta – as I am a PhD, not MD.  But she had already failed on other kinds of treatments via other doctors, including medication, talk therapy, and was at the end of her rope. She was very, very depressed – but wanted to get better – she just had no idea how to go about it.

I talked to her about tDCS and the published information that shows improvement for some challenging depression cases. I showed her how to use a tDCS device and where studies have shown electrodes should be placed for treating depression – but left it up to her to treat herself or not.  She immediately started once-a-day 25 minute tDCS sessions (1.5 mA). Within five days her mood had lifted greatly and I think she had moved out of the suicide danger zone. She continued daily tDCS treatments for the next four weeks. As she did so, her depression fully lifted. She recovered so well that she felt motivated to enroll in a technical school to learn a new skill – and in her classes scored the highest on all tests (a side-effect of the tDCS?)

She now lives a normal, happy life (yes – with its ups and downs like anyone.)

Seeing people get their lives back in such a simple way, with no debilitating side-effects, has made me a cheerleader for tDCS.

Does it work for everyone? It won’t work for everyone – but what treatment (or pill) does? My observation is that tDCS works for those motivated and willing to consistently use it in the way research studies have shown it should be used. tDCS in combination with talk-therapy seems particularly well suited to treating depression – which in many has its roots in a brain dysfunction – not evil-spirits, selfishness, or a bad attitude as some suggest. By modifying the firing potential of the neurons in key portions of the brain it seems real healing can be achieved.

Review: New tDCS Device from SSD

Super Specific Devices has released a tDCS device that might be just right for that DIY tDCS person on your holiday shopping list (perhaps yourself!) The new tDCS device is a well-built variant of a DIY tDCS design that has floated around the internet for about two years now.

The Super Specific Devices (SSD) device offers solid performance, based on a 9 volt battery, and provides a feature I consider nearly essential – a meter that allows you to verify the current being delivered during your tDCS session.  That is coupled with a potentiometer (dial) that allows you to vary current level, making it easy to set 1, 1.5, or 2 mA or anywhere in between.  The user can also gently ramp current up and down using the dial – so discomfort and phosphenes are reduced or eliminated.

(Jack on the side for standard TENS style electrode cables)

What Comes in the Box

The SSD tDCS device is fully assembled and comes with a starter set of stick-on electrodes, a couple of sponges, a connecting wire, basic instructions, and a headband. The unit does not come with a 9 volt battery or any sort of an application manual.  Like many of the US-based cottage-industry building tDCS devices, they leave it up to the purchaser to do their own research on the internet to decide what additional electrodes, electrode placements, etc. are appropriate to the purchaser’s situation.  The intent is probably to keep the company off of the FDA’s radar as the SSD (and similar devices) are not marketed as medical devices – nor does the company provide medical advice.


To use the SSD tDCS device, one needs to insert a 9 volt battery into the socket on the side of the unit, plug in and apply electrodes, and then use the power on-off switch and dial to operate the unit.  To start a session, the dial should be rotated fully counter-clockwise (minimum current) and then switched on. An LED indicator just above the on-off switch will light to show that power is on.  Assuming electrodes are in place, the user then begins rotating the dial clockwise, watching the meter for rising current level.  Note that due to skin resistance, there is a lag between dialing in a higher current level and that level actually being achieved.  It can take a couple minutes or more for current to rise to a set level and stop. An alternative is to turn the dial significantly clockwise and turn it back down as your desired current level is achieved.

On my sample unit, even with electrodes shorted and the dial set fully clockwise, the unit would not deliver more than about 2.7 mA. On the inside is an LM 334 current regulator and a series-connected current limiting diode that limits output current to 2.7 mA – as I found in my testing (good safety feature). This is a nice, simple, practical, current control setup that should prove reliable for many, many years.

(Good build quality. LM 334, CRD and resistors on small circuit board, solder joints were solid, wires nicely dressed.)

Another nice feature of the SSD tDCS device is having a jack on the side of the unit for electrode wire attachment – it’s the standard TENS size that lets you use a variety of connecting wires supplied by Amazon, medical supply houses, etc.

(Electrode wire jack and current adjustment knob can be seen here.)

What Would I Change?

I’ve built several tDCS devices using the same basic design of the SSD tDCS unit.  So I’m very familiar with use, operation, and limitations of this type of device – and I’m allowed to nit-pick.

First, let’s be clear – it’s my opinion that this unit will operate as described by the company and will provide clean, regulated DC current for most common tDCS scenarios.

I happen to prefer using a type 23a 12 volt battery in my tDCS device designs.  Why? 9 volts is sometimes insufficient to overcome losses in the electronics, electrodes, and skin to provide the desired 1, 1.5 or 2 mA used in tDCS sessions.  In fact, 9 volts will probably not be sufficient if one of the electrodes is located on the shoulder or arm for a montage you wish to use. Sometimes a 12 volt battery will barely do it – but the additional 3 volts really seems to help. The downside of the type 23a battery is they don’t last long (2 or 3 months is normal with a lot of use.) But they, like 9 volt batteries (which last much longer in a tDCS device) are cheap (Amazon, Ebay.) I’m betting SSD went for long battery life (and easy availability of cheap batteries) in their design criteria.

( 9 v battery socket on the side. Aesthetically, it would be nicer to locate it inside the roomy box.)

By the way, many “commercial grade” tDCS devices use a voltage boost circuit that can raise delivered voltage to between 60 and 80 volts – as needed – to overcome skin and electrode resistance (like foc.us, Activa Dose II, and others). These boost circuits sometimes add discomfort for the user, increase device cost significantly, and so are not present in lower price tDCS devices like the one from SSD.


If you are looking for a well-built, inexpensive, tDCS device that includes a lot of good features (meter, adjustability, good current regulation and protection, and more) then this might just be the unit for you (or someone you know.)  You’ll need to do your own research on tDCS, its appropriateness for your situation, tDCS safety, and the electrode placements that address your need.  See any of the following as a starting point:




www.pubmed.gov (search for tdcs)

…and Google search tDCS

The Super Specific Devices tDCS device sells for $90 at http://www.superspecificdevices.com/ Oddly it sells for a bit more on ebay.com (go to ebay, search for tDCS). SSD also sells the same unit with a digital display for $20 more if you prefer (at their web site and ebay).

Based on my evaluation and use of a sample unit, it’s my opinion that the SSD tDCS device (design, build, and features) is a good value.

Use Your Own Electrodes with the foc.us tDCS Headset

The foc.us headset comes with built-on sponge electrodes and has the ability to support wire connected electrodes via a small connector on the back.  You can buy the accessory kit from foc.us and in it receive wire connections for snap-type electrodes (usually stick-on).  For anyone with hair (not me sorry to say), you may want to use sponge electrodes (like the popular Amrex 2×2 or 3×3).  The Amrex electrodes use banana style connectors – so you must adapt the foc.us wires or create your own.  I chose the latter route.

Here’s what you need:

  • Radio-Shack PN 273-334 “Adaptaplug type A” – it measures 2.35mm OD x 0.7mm ID.  If someone has a better connector or source suggestion, please let me know.
  • Wire with the desired connector type at one end. I prefer alligator-clips as they provide great flexibility.
  • Head-shrink tubing (available at Radio Shack)
  • Solder and soldering iron

You can see from the pictures that if you are looking at the back of the connector, pins down, the pin to the right is the Anode (+) when plugged into the headset (I checked this with a DVM). I marked that side of the connector with a red sharpie.

So all that has to be done is solder your leads to the pins, use some heat-shrink tubing to cover them and away you go!

(Adaptaplug A from Radio Shack)

The plug is 2.35mm OD, 0.7mm ID)

I marked the pin that corresponds to the anode with a red Sharpie)

A little soldering, some heat-shrink tubing and done!)

With the adapter complete, you have much more flexibility using whatever electrodes you like with the foc.us headset.

BTW wire color does not matter. I just happened to have a bunch of green and yellow clip leads. In this case, I soldered the yellow lead to the anode pin.

You may prefer to buy a cable like this and add lead-wire and connectors that you prefer:

2.35 mm DC Plug for headset
Pre-assembled cable from EBay – about $3 with shipping! Search for 2.35mm DC cable.)

One more thought: The connector used for external connections is a bit fragile.  You might want to consider using some Velcro or similar material to provide some strain relief if you frequently use external electrodes.

A Velcro wrap used for strain relief)

Your ideas and suggestions are welcome!


The foc.us tDCS Headset, Review Part 4, Electrode Placements

Note: If you are new to tDCS and/or the foc.us headset, may I suggest that you read parts one through three before reading this post.  You’ll better understand what I present here if you have a little context. Also, you might want to know that the default “built-on” electrode configuration for the foc.us headset addresses one depression and learning/memory montage “right out of the box”.

Great Product!


The more I have used this headset, the more I have come to believe that it is an almost ideal tDCS device.  It’s features and versatility make it a breeze to setup and a pleasure to use.  I have become a real fan of not being tethered to a traditional tDCS device – wires, box, electrodes, head-band(s), etc. My guess is that foc.us will be VERY successful – ultimately selling these headsets to end-users, medical practitioners, and the research community.

Electrode Placements

I’ve had repeated requests to show electrode placements for various scenarios using the foc.us headset. As you look at these, remember, they are just examples. There are alternative placements and new tDCS montage information being published almost every day!  What I hope to convey is the versatility the foc.us headset provides through various electrode placements. So here we go…


The most common depression treatment using tDCS places the anode at F3 (high on the left forehead) and the cathode at FP2 (just above the right eye on the forehead).  See below…

Depression Montage
Typical electrode placement for depression treatment.)

The unusual foc.us “built-on” electrode placement puts the anode at FP1 and F3 and the cathode at FP2 and F4.  So yes, it supplies current in the general area suggested for depression treatment.  Has this unusual arrangement been scientifically studied?  Not to my knowledge. There is anecdotal evidence that indicates that it works.  BTW Notice the air-gap between the sponge and the “head” in the upper right of the photo.  Be careful when you put the headset on your “real” head that there are no air-gaps.)


This montage is been in the press of late and is easy to do with the foc.us headset with the accessory kit. Normally, the anode is placed at about T4 (the right temple) and the cathode at about T3 (the left temple.)

Savant Learning Montage
Electrodes are placed on the temples)

The accessory kit includes wire electrodes that connect to the back of the headset. You can then attach the electrodes wherever your montage requires.)

If you use the wire electrodes, remember that the “built-on” electrodes remain active.  You can use them if appropriate or remove the sponges to not use them.  In this case, the built-on electrodes are not used at all – in fact you can take the headset off and set if on your desk – or do what I do, just let it rest on your neck.)

If using the wire electrodes, the headset does not need to be on your head!)


An interesting memorization and learning montage involves placing the anode at FP1 (above the left eye on the forehead) and the cathode at FP2 (above the right eye on the forehead).

Memory and Learning Montage
There are other variations of “learning” electrode placements on the web.)

As with the depression montage shown earlier, the unusual placement of the built-on electrodes is “more” than required for this montage. Possibly the upper sponges could be left out to more precisely match the montage requirements. However, current density could be too high or irritation might result as the sponges are small. Research is needed! An alternative is to use the wire electrodes and not put the headset on the head at all.)


Chronic pain is addressed in at least a couple of different montages.  One example is to place the anode at C4 (above the right ear, halfway to the center of the head) and the cathode at FP1 (above the left eye on the forehead).  There are other montages for chronic pain – so look those up on the web if the one I show is not what you are looking for.) Another montage places the anode at either C3 or C4 and the corresponding cathode at FP1 or FP2 on the same side of the head (left or right) to treat chronic pain on the opposite side of the body (left or right).

Chronic Pain Montage
One of the reported chronic pain montages.)

This is another example of how versatile the foc,us headset can be. Use the wire electrodes for this chronic pain montage and set the headset on your desk or leave it resting on your neck – with no sponges.)


So there you are – four examples of tDCS montages using the foc.us headset.  What a great and versatile product. It’s unfortunate that the default treatment in time in the headset is 10 minutes.  The norm in tDCS treatment is 20 minutes (sometimes 30 minutes.)  Once the iOS and Bluetooth issues are resolved, changing treatment time will be the first thing I do!  In the interim, once one session is complete, you can simply touch the button on the back of the headset one time to repeat a 10 minute treatment.

How else can I help you with this headset or tDCS in general? Please feel free to send me an email at brent@speakwisdom.com

The foc.us tDCS Headset, Part 2, Electrode Basics


(foc.us tDCS headset showing “built-on” electrodes and sponges)

Impressive – But…

I continue to be very impressed with the new foc.us tDCS headset.  It brings to the table a huge array of features in a package that is relatively user-friendly (and will become more-so when its iOS and Android apps are available.)  If your interest is learning enhancement or treatment of depression, the headset alone is probably all you need.  So far, I have found it easy to use and reliable.

The accessory kit adds capabilities for placing electrodes in other locations on the head and shoulders for treatment of chronic pain, experimenting with “savant” learning, and other research projects. In this blog post, I want to briefly summarize the basics of electrode use using the “built-on” and accessory electrodes. I have also included a summary of basic operation for those curious about using the headset (or those having trouble understanding the manual.)

Electrode Placement

The “built-on” electrodes place the anode above the left eye and high on the left forehead (two sponges.)  The cathode is in the same positions but on the right side.  These positions, while perhaps not “ideal” in the eyes of some are probably close enough to published locations for learning enhancement and depression treatment for many or most users.  For depression, some have a preference for moving the cathode off to the right shoulder, but that requires the accessory kit. The headset itself is quite capable and will probably satisfy the needs of most.

Using the External Electrodes

You have to give foc.us some applause.  They designed a LOT of capability in to a fairly inexpensive package.  This is the first really versatile tDCS device that has a clean, simple design, has high ease-of-use – and doesn’t cost a fortune as many other “commercial” offerings do.  tDCS is now within reach of many more who really need it! For those not satisfied with the built-on electrodes, you can do your own thing for special treatments or research with the accessory kit.  It includes necessary wires (and other items) along with a small number of “TENS” style stick-on electrodes.


(Cathode wire plugged into the back of the headset)

Important: The Wires

The kit includes a two-wire (anode & cathode) lead with good length, allowing placement pretty much as you see fit.  Uniquely, there is a single wire anode and single wire cathode included too. These are very useful when you want to use the built-on anode (or cathode) and have the opposite charge applied at a different location.  As mentioned, for depression, users may prefer the built-on anode, but want the cathode placed on the right shoulder.  The single cathode wire makes this simple to do.


(Leads plug in to the back of the headset)

CAUTION: Voltage continues to be available via the built-on electrodes even if one of the accessory leads is plugged in.  You will need to remove the appropriate sponges (cathode or anode) when using an accessory wire.  So for example, a person seeking to treat depression would leave the anode (left) sponges in place, remove the cathode sponges (right side), and then use the cathode wire to place an electrode on the right shoulder.

If you leave sponges out, you need to be VERY CAREFUL that skin cannot come in contact with the copper plate inside the sponge holder (from an odd skin-wrinkle or tag.) If it does, a burn could result. An accessory CAP of some kind would be a nice safety feature – to cover the unused sponge holders. Perhaps the iOS/Android apps will allow disabling unused built-on electrodes – we’ll have to wait and see.  Safety caps would still be a good idea.

CAUTION: The plus and minus marking on the anode and cathode leads is BARELY visible and could easily lead to an error.  I suggest MARKING the leads in some much more visible manner (I used red and black zip-ties for the purpose.)


(Can you see the minus sign on the back of the electrode clip?)


(You will want to clearly mark lead polarity. Zip ties work.)

Coming in Part 3

In my next blog post I’ll have more information on operation, use, electrode placements, and more.  Please feel free to send along any questions or comment.  I’ll try to address those in the next post or two.  brent@speakwisdom.com

FYI: Summary of Basic Operation

Make sure the headset is charged

  1. Switch in “W” position
  2. Green light indicates charging

Turn it ON

  1. Flick the switch to the “O” position
  2. Touch the sensor (center back of the headset) for TWO SECONDS to activate it
  3. If you touch the sensor for three seconds or longer, the headset enters pairing mode (fine if desired, otherwise, switch to “W” then back to “O” and return to 1. above.)

To BEGIN a tDCS Session Already Configured

  1. Touch the sensor ONCE
  2. A four second count-down begins (time to put the headset on!) Current then ramps up to the desired level (more below.)
  3. Current will automatically ramp down at the end of the session

To END a tDCS Session

  1. Touch the sensor
  2. Switch to the “W” position to turn off the headset

Changing Session Settings

Set Mode

  1. Turn the headset on (switch set to “O”)
  2. Hold the sensor for two seconds to activate the headset
  3. Tap the sensor TWICE
  4. The headset will cycle through its four modes
    1. DC Sine-Wave – Logo brightness will rise and fall over 5 seconds
    2. Constant DC (DEFAULT) – Logo remains on for 5 seconds
    3. Pulsed Current (0.5 mA min) – Logo brightens and dim in 5 seconds
    4. Random Noise (0.5 mA to max random) – Logo brightness changes erratically
  5. When the logo reaches the state you desire, touch the sensor ONCE

Current Setting

  1. Next, the Logo will glow for three seconds at each of the below. Press the Logo to select.
    1. 0.5
    2. 1.0
    3. 1.5
    4. 2.0 (Only settable for use with external electrodes)
  2. Once current is set, foc.us headset returns to the ready state. You can begin a tDCS session by touching the sensor ONCE or…

To Confirm Settings

  1. Touch the sensor THREE times and the above Logo displays will appear for confirmation.

Factory Reset

  1. Touch and hold the sensor for 30 seconds.

tDCS – The Must-Have Tool of the 21st Century?

I’ve been completely fascinated by tDCS since I first learned of it a couple of months ago. What other technology is so simple yet has the potential to help so many – whether it be to treat depression, Alzheimer’s, ADHD, or just dramatically improve the ability to learn almost anything. What else does all of that with almost no risk or side-effects? Why this isn’t the lead story on the evening news and your local paper is hard to explain.

(A commercial tDCS device and electrodes.)

There are dozens of published scientific studies of tDCS and more than a hundred new studies underway. Consider this: “Air Force researchers were able to cut training time in half during instructional sessions on video simulators using tDCS. Utilizing an Army battle-training simulation video which requires soldiers to detect signs of danger in a landscape of dilapidated buildings and abandoned cars, and scan for things such as explosive devices and enemy gunmen, the tDCS group showed twice the improvement over a short period of time.” (From transcranialbrainstimulation.com) …Or this: “Stimulating the brain with a weak electrical current is a safe and effective treatment for depression and could have other surprise benefits for the body and mind, a major Australian study of transcranial Direct Current Stimulation (tDCS) has found.” (From sciencedailynews.com)

Briefly, tDCS involves running a tiny current (1 to 2 milliamps) through the skull via saline soaked sponges. For healing, typically a daily 20 minute treatment is repeated for 30 or 60 days – though there is wide variation depending on the objective of the treatment. Learning session may involve 30 minutes of tDCS once per day. Enhanced learning continues for up to hours after the tDCS session has ended. Studies show enhanced retention months later.

Because buying a tDCS unit normally requires a prescription and commercial units cost many hundreds or thousands of dollars, lots of amateurs have taken to building their own units – typically for $20 – $100. The best, very simple tDCS design I’ve seen is below – but there are probably plenty I am not aware of. The design below uses a type 23a small 12 volt battery instead of the more common 9 volt battery.

(Simple tDCS design using parts commonly available on the web.)

Where to place electrodes is another interesting aspect of tDCS. Functional maps of the brain are commonplace, so electrode placement is fairly well pinned down. There are many articles on the web that describe electrode placement in great detail. The diagrams below represent the best simple summary of popular electrode placements that I have seen. I do not know who created them – they show up in several places on the web. (I’d be happy to give credit or a link.)

(From the web)
(From the web)
(From the web)

(From the web)

Finally, there are interesting questions about tDCS that educators will have to deal with in the coming years. tDCS, as a learning technology, has been clearly shown to improve learning speed and retention in significant ways. High-schoolers and college students are figuring this out (see YouTube and elsewhere.) So how will we advise young people when it comes to tDCS use? Will students check out tDCS units like they would a laptop from the school media center? What about students who use it and excel vs. students who don’t and struggle? (A new kind of haves and have-nots.) There is a whole range of questions that will have to be tackled – tDCS WILL become a factor in the world of education – soon.

(It’s already happening. Scientific American. From the web.)

For anyone interested in tDCS, my best recommendation is to read, read, read. There is a wealth of information on the web and more appearing constantly as new experiments are performed and studies are published. Stay tuned, this is important!