Time to Take Another Look At foc.us tDCS and more


About two years ago foc.us burst on the do-it-yourself tDCS scene with a headset marketed to “gamers” – claiming to offer improved game performance (higher scores).  A few folks like myself recognized the foc.us headset (V1) for what it was – a remarkable, capable tDCS device that could be used for ANY tDCS related purpose including treating depression, chronic pain, enhancing memory, etc. – and yes, improving game scores!  The V1 headset was truly a leap beyond anything else available to the DIY community offering an all-in-one headset that could be controlled via Bluetooth, offered built-on and external electrodes, all in a very nicely designed package.

(Famous or infamous foc.us V1 ad campaign)

Critics quickly emerged, as they often do, describing customer relations related problems with foc.us – many justified, and technical issues with the product – many unjustified.  It seemed foc.us was surprised by their own success and unprepared for the order volume and normal support requirements of such a leading edge product. By the time foc.us got its organizational problems resolved, the V1 was winding down and the company was preparing to launch the V2.

The foc.us V2

Several months ago, Transcranial Ltd. launched it’s new foc.us tDCS product, the V2. It, like the V1, sets a  high bar for the DIY tDCS market. In a tiny package easily small enough to misplace with your car-keys, foc.us engineers included all of the technical features of the V1, plus the added versatility of upgradeable firmware (new features), display screen with scrollable selection, redesigned and industry leading headsets, the ability to use 3rd party headsets and related accessories, and more!

(The foc.us V2. Tiny! Awesome!)

Interestingly, foc.us via their advertising, now seems to recognize the value of their technology for what it is, a real cranial stimulation device – not just for gamers – but for anyone seeking the benefits of tDCS and more.

The V2 ad campaign is more general – making clearer the broad capabilities of the V2.)

Since my initial posting about the V2 (see http://bit.ly/1Jilfpg ) Transcranial Ltd. has upgraded the feature set of the V2 in significant ways!  The V2 now supports tDCS, tACS, tPCS, and tRNS as well an upgraded application for Android devices and soon iOS. The V2 can no longer be referred to as just a tDCS device – it’s now a fully capable, research grade, cranial stimulation device!

It’s a Software World Now!

If you purchase a V2 (or own one now), you may wish to update its firmware periodically to take advantage of new features.  Here are some key steps:

  1. Go to the foc.us web site and create an account: https://www.foc.us/customer/account/login/
  2. Log in with the account
  3. Connect your V2 doc to your capable PC (or Mac)
  4. On the left of your screen (once logged in), select “My Downloadable Products”
  5. Click the “Microsoft Software” (or Mac) download button and install
  6. Run the installed application and allow it to check and upgrade your V2 to the latest firmware


An Android app is available (search for wave tdcs in the store.) An iOS app for the V2 is due anytime (the old V1 app does not seem to work with the current V2 firmware.) I will say that the on-screen display of the foc.us V2 is so good and so versatile that I’m not convinced that the apps currently add much value. Transcranial Ltd. is soon to release a EEG capability called “Quantum” that will apparently link to the V2 – and will probably make the apps very functional and important to use.

(foc.us Android app)

Anyway, you must pair the foc.us device to your Android or iOS device to use an app. Here are normal pairing procedures:

  1. Make sure Bluetooth is turned on on your Android or iOS device
  2. Turn on the foc.us V2 and scroll to Settings, Bluetooth, and make sure Bluetooth is On.
  3. Very quickly your handheld device should find the foc.us device and request you type in a code number that you will find displayed on the foc.us device. Do that and you are ready to go!
  4. Run the foc.us app, set the desired mode (tDCS, etc.), max voltage (20 is typically fine), current (1 to 2 mA), time (typically 20-25 minutes), sham should be off, and START

I’ve noticed that the Android app does not display remaining session time.  You can see it easily on the foc.us device by tapping the blue joystick.

More Detailed Instructions?

Like most tDCS vendors, Transcranial Ltd. is trying to stay off of the FDA’s radar by making it clear that they are not producing a medical device – so they shy away from writing application guides and notes. This frustrates some. Users are left to their own creativity to learn how to properly use and get full advantage from a foc.us device (V1 or V2). To help V1 headset users, I wrote a pretty detailed set of instructions ( see http://bit.ly/1FSf6wb ) that seem to be popular.  Would you like an equally detailed set of instructions for the V2? Let me know – if there is sufficient interest I’ll be happy to put that together.

Finally, I’ve taken a good bit of heat via email and blogs for being a fan of foc.us. Unlike some, I saw very early on that their unique product(s), if used correctly, could be used to improve the lives of many – and that has turned out to be true. Foc.us continues to be one of my favorites in the world of tDCS and cranial stimulation and I, for one, anxiously await their next DIY leading-edge products and the pace they set for the industry.

I look forward to your comments and questions.



1. Photos in this blog are from the internet and include images from foc.us and speakwisdom
2. If you are new to tDCS, please read and study carefully before taking any action related to tDCS or any cranial stimulation technology.  I suggest as a starting point:
a. speakwisdom.wordpress.com/tdcs/
b. diytdcs.com
c. www.reddit.com/r/tdcs
d. http://www.pubmed.gov (search for tDCS)


Using the foc.us V2 with the Gamer or Your Own Electrodes


In part 1 of my series on the new foc.us V2 tDCS device, I introduced the basic components of the V2 as well as its user interface. I continue to be pleased with the V2 as a user and want to pass along some ideas related to electrode use.

The foc.us Gamer Headset

Foc.us offers two headsets for the V2, the Edge and the Gamer. The EDGE is a special purpose headset designed to facilitate experimentation and research on the use of tDCS to improve athletic ability. As I mentioned in the last post, this is an area of tDCS that is ripe for exploration. A few studies have already been posted that hint at possible uses for tDCS and improvements in physical ability. This will be a very interesting application of tDCS to watch as results from various tests are posted. The EDGE headset is not a general-purpose tDCS headset and should NOT be selected by most users.

The GAMER headset is a more versatile headset for the new or experienced tDCS user. It is made up of a flexible metal band and two electrodes that attach to the band. It is highly adjustable for head-size and comfort. “Out of the box” it is designed to allow stimulation of the pre-frontal cortex, an area associated with memory, learning, etc. It happens that the electrodes of the GAMER can be used independent of the included band – allowing electrode positioning for “savant learning”, treatment of chronic pain, depression, etc. Note: the electrode plainly marked “Left” on the inside of the sponge frame is the anode (+) and the electrode marked “Right” is the cathode (-).

(The Gamer headset.  Best choice for most.)

(The Gamer headset in its case.)


(The Gamer on my “test head”. Note electrodes are positions over the pre-frontal area.)

(You can use the Gamer electrodes without the supplied metal band and place them where you want. Here I’ve used an elastic band to position the electrodes for “savant learning”.)

(Here is another example with the electrodes positioned to treat chronic pain. In this example, the cathode would be placed on the upper arm or shoulder with another band.)

UPDATE – March 2015

foc.us has updated the firmware on the V2 so that the resistor that tells the tDCS module which headset is connected is no longer needed.  FURTHER – they are also released a patch cable to make attaching 3rd party electrodes even easier. See (  http://www.foc.us/tdcs-tens-cable-adaptor ).  The text below is left for historical reference only.

Using Your Own Electrodes (Amrex)

If you are pretty good with a soldering iron you can easily adapt any electrodes you prefer for use with the foc.us V2. The jack on the V2 tDCS device is a four conductor, 2.5 mm type that has been used on some cell-phones and portable audio gear. Connect your electrodes to a four conductor, 2.5 mm plug and a small resistor and away you go!

Plug Wiring

Tip and Ring 1 – a resistor across these two tells the tDCS device the model of headset connected. (300 ohms for the Edge, and 2,000 ohms for the Gamer by my measurements)
Ring 2 – Cathode connection (-)
Ring 3 – Anode connection (+)

To test this, I used a small RadioShack proto-board and broke out the 4 conductors for easy investigation and tinkering. I used a 100 and 200 ohm resistor in series to get the 300 ohms needed to let the V2 “think” I am connecting an Edge headset, even though I use popular Amrex 3x3s. Actually it seems not to matter whether the V2 thinks an Edge or Gamer is connected – you can still set all the desired tDCS treatment times and current levels.

(Note the four conductor plug. It is broken out on the proto-board with T, 1, 2, 3 as described above. I use this example with Amrex 3×3 electrodes.)

Perhaps in future firmware, foc.us will include special features for 3rd party headsets that use a different resistance identifier.
BTW Soldering wires to a four conductor, 2.5 mm plug is not for the faint of heart. It’s very easy to short contacts and generally make a mess. I suggest buying a pre-wired 2.5 mm plug from Parts Express (or similar). Their part number is 090-504.


So there you have it. I suggest that you either buy the foc.us GAMER headset with your V2 and use it as is or with your own headband as I have shown above – or do your own thing with a 4 conductor plug and whatever electrodes you prefer.

Please feel free to send along comments and suggestions related to this post or a future one you would like to see.

The NEW foc.us V2 tDCS Device and Headsets, Part 1

(The tiny V2 module is now the core of the foc.us tDCS product line.)


Once again, foc.us has distanced itself from the rest of the tDCS device pack. If you are in the market for an innovative tDCS device that is sophisticated and simple to use, I think you will be very pleased with the foc.us V2. tDCS is all about delivering a tiny current to the brain in order to improve it or provide relief from a brain-related condition. Here is a way to do it with a cool device that works well!

Enter foc.us

The first foc.us headset moved the bar on tDCS devices by offering a huge feature set (built-on or external electrodes, wearable, Bluetooth support, iOS app, etc.), and a moderate price. I don’t have any sales data on the foc.us V1 headset, but I’ll guess foc.us sold more than a few.  I happen to own more than one and use them often. I’ve also helped many others achieve tDCS success with the foc.us v1.

(The foc.us V1. Slick. Innovative.)

As a radically new design from a brand-new start-up, the foc.us V1 was not without its problems or detractors. There were production problems, support problems, unpolished features and more – that for some made it hard to see the real core value of the headset as a tDCS treatment device. But given how far foc.us pushed the DIY tDCS market, those of us who really learned how to use the headset were (and are) thrilled to have it.

The foc.us V2

foc.us did not stand still though. Based on experience with the v1, user input, and their own vision of what tDCS could become, the foc.us v2 tDCS device and accessories have been created and are now moving toward distribution.  The new device has three basic parts of which the buyer can purchase as desired.

  1. foc.us V2 tDCS Device – REQUIRED (does the work of producing the tiny DC current used in tDCS.)
  2. Gamer Headset (plugs into the V2 device. Electrodes positioned for stimulating certain types of learning)
  3. EDGE Headset (Plugs into the V2 device. Electrodes positioned to possibly enhance athletic performance.)

The V2 tDCS device itself is now a tiny module not much bigger than some USB flash-keys.  It is programmable, has a graphical display, a joy-stick like control for selection of desired tDCS parameters, and is rechargeable and updateable (firmware) via a USB base.

(As expected from foc.us, innovative design and nice packaging.)

The Gamer headset is a flexible band with two electrodes designed to reach the pre-frontal cortex area of the brain – an area thought to respond nicely to tDCS for improvement in some types of thinking and learning (concentration, planning, judgment, etc.)

(The new foc.us Gamer headset. Bigger sponges, very comfortable. Shown on my “test head”. There are better photos at www.foc.us)

The EDGE headset represents new ground for a commercial tDCS device.  Many of us have wondered how long it would take the world of athletics to discover tDCS and the potential it holds for improving performance in many competitive and non-competitive sports.  To that end, foc.us offers the EDGE headset designed to place the anode in the area of the premotor cortex (coordinates complex movements) and the cathode on the upper arm.  Much research and experimentation in this realm of tDCS is needed, but suffice it to say that one day the top performers on your favorite sports team may be using tDCS during at least some of their training.

(foc.us calls attention to the possibilities for athletic improvements via tDCS and the EDGE headset. Shown on my test head. Foc.us headset sponge-sockets are now nickel plated – instead of copper as in the v1. Better images are at www.foc.us)


I was fortunate enough to have received a foc.us V2 at the beginning of December, 2014, with an early firmware and feature set. Suffice it to say that, even in its early form, it performs well and is very easy to use.

Using the V2 is simple: Unpack the V2 tDCS device and place it on the USB charger for an hour or two to fully charge. Meanwhile, remove two sponges from the sealed envelope supplied with your foc.us headset, wet them a bit (saline if you prefer), and place them in the sponge sockets (or use your own electrodes and headband as described in the next blog post.)

With the headset in place and plugged into the V2 device, press the blue joystick on the v2 tDCS device to activate it.  Then simply step through the prompts to setup your tDCS session parameters.

(The display is easy to read. Duration and current are easily changed.)

Your tDCS session will begin with a short ramp-up time and then a count-down of the session time remaining. Actual current delivered is displayed and graphed.  You can press on the joystick at any time to immediately end a session.

(Prompts are simple and clear.)

For you techie folks: Note that the foc.us V2 does contain a boost circuit to overcome electrode and skin resistance – as do many commercial tDCS devices.  I measured a peak of 56 volts as the V2 tried to compensate for my high-impedance load test and deliver the selected current level.  At no time was I ever able to exceed the current level I had programmed on the V2 device.

A Few of the Many Enhancements Over the foc.us V1

  1. Very small, portable, tDCS device. You could easily Velcro it into your cap or just put it in your pocket. It is easily programmed for desired tDCS settings.
  2. foc.us electrode sponges are much larger (and better quality) than with the v1 for better current distribution
  3. More comfortable headsets
  4. Can be used with foc.us, 3rd party, or user provided headsets and electrodes


  1. Three or four tDCS sessions seems sufficient to drain the battery in the early production device. I think it will be a good habit to put the V2 device on its charger when not in use.
  2. There were complaints that foc.us seemed overwhelmed when the v1 was released about two years ago – leading to spotty technical support and order-issue resolution problems. Has foc.us learned from the V1 experience?
  3. The V1 IOS app never seemed to reach a solid feature completion. It works – but… Will the V2 app be better? foc.us says it will.  They have a new programming team and will release a new app for the V1 and V2 in the January/February timeframe.  But to be clear, you DO NOT need an app to use the V2 very effectively.

Overall Impressions

I’m very pleased with my early copy of the V2.  It works well, is tiny, easy to use, and produces clean, predictable output.  The new foc.us headsets are innovative and comfortable. The V2 represents a nice step forward for foc.us and for the DIY tDCS community. I look forward to continued development of the V2, firmware, apps, and 3rd party add-ons that are likely to come.


Pricing is about the same as with the V1 (it was about $250 plus $50 for a needed accessory kit.) The V2 is $199 for the tDCS module. foc.us supplied headsets are priced at $99.  A pack of 12 foc.us sponges is $5. You are free to use 3rd party or your own electrodes if you prefer (details in my next post.) See www.foc.us for ordering details.

Bottom Line

The foc.us V2 is clearly more sophisticated and better designed than the typical tDCS device in the market right now.  Yes, it costs more than entry-level devices – but as the saying goes, “you get what you pay for”.  If you are serious about tDCS for yourself or someone you know, the foc.us V2 deserves your consideration.

Brent Williams, PhD

Coming at www.speakwisdom.com

Over the next weeks and months, I’ll post a number of articles about the foc.us V2, use, applications, and more.  Feel free to contact me with your questions and comments via brent@speakwisdom.com

(My crude but effective breakout of the new V2 four conductor plug. Yes, you can use Amrex and other electrodes.)

foc.us tDCS Headset Battery Replacement

I have a foc.us tDCS headset that was becoming unusable due to a failing battery.  I decided to replace the battery myself rather that take the time and effort to return it to foc.us for repair.  I thought you might want to see what is involved in battery replacement.  It’s not a job for a novice – good soldering skill (and good vision) is required.  If you don’t want to tackle the job yourself, a local battery replacement shop might be able to do it as they often do soldering work.

The battery in the foc.us headset is a small 3.7V, 150 mAh lithium polymer type (model 041230) and like any battery is prone to eventually fail. It is available from a number of sources – including EBay where I purchased mine for $3. By the way a single AA alkaline battery has a capacity of about 2,000 mAh – thus explaining the need to charge the foc.us headset fairly often.

To replace the battery, you must remove the back cover which is held in place by two small torx-style screws.  If you don’t have a small torx drive around, you may find a small flat-blade screwdriver will suffice. Once the screws are removed, gently bend the headband back and the cover can be lifted away. Inside you will find a small circuit board, the lithium polymer battery, and very thin, delicate wires.  Use great care as you work to avoid breaking a wire.

You will need to gently lift the board off of the plastic pins that position it as the solder connections for the battery are on the underside of the board. You can then turn the board over for desoldering the old battery and soldering the new battery in place.

With the cover removed, the battery, circuit board, and thin connecting wires can be seen.)


(I use a “third hand” to hold the board while I do soldering work. Note the red, positive battery lead is to the outside edge of the board.)

Once the new battery is soldered in place, you can return the circuit board to its alignment posts, place the battery on top of the circuit board, and then put the cover back in place. Be careful not to crimp the fine wires from the battery or those running to the electrode sockets.  Once the cover is back on, reinsert and tighten the two torx screws and you are done!

I suggest you give the headset a good two or three hour charge and it should be ready to go.



Yea! The new app for the foc.us tDCS headset has arrived!

After a long, long wait, we finally have a working iOS app to control the foc.us tDCS headset.  While still needing some polish, the app released in January of 2014 gets the job done, allowing control of current, duration and treatment type.

(foc.us app, ver. 2)

To get started, you need an iPhone 4s or later or and iPad 3 or later using iOS 7.  Given those conditions, go to the App Store, search for foc.us and you should have no trouble locating and installing the app.  Then the fun begins!

First – be aware that though this is version 2.0 of the foc.us app, think of it as a 0.99 version. It works, but has much polish and stability to be added yet.  You will struggle with it a bit, but once you get the hang of it, you will find it usable in accessing the features of the foc.us headset. As foc.us adds some polish, this should become the app we’ve all been waiting for!

Getting Connected

Make sure your foc.us headset is charged and ready to go and that Bluetooth is enabled on your iOS device.

To Connect:

  1. Start the foc.us app
  2. Place your headset in “Ready” mode by touching the touch-button for three or four seconds.  It should buzz and the blue foc.us logo should blink.
  3. Touch “Bluetooth” at the bottom of the app screen.  The headset should show in the list of available Bluetooth devices as “foc.us gamer”.  Touch “Connect”. Note – if you take too long, the headset may drop out of “Ready” mode.

(App and headset connected)

  1. Touch the “Current” circle and move the slider to the desired current level.  If you are new at all of this, I suggest 1.0 mA. Touch “Change” to confirm.

(Setting the current level in the app)

  1. Touch the “Duration” circle and move the slider as desired.  Normally, tDCS sessions are 20 minutes (in research anyway.) Touch “Change” to confirm.
  2. Touch “Mode”.  Unless you have a specific research reason to do otherwise, I’d pick “Continuous” – that is tDCS.

(Pick Continuous for tDCS)

Once the above selections are made, the tDCS session should start immediately.

If your tDCS session does NOT start immediately, the app and your headset have probably lost contact with each other (even though the Bluetooth screen shows otherwise). I suggest closing the foc.us app (double-click home on your iOS device, and flick the foc.us app UP to close it).  START OVER at step 1 above.

During the tDCS session, the “Duration” will count down minute by minute.  At the end of the session there is a brief “buzz” from the headset to let you know the session is complete.

Duration counts down as session progresses)


  1. The app and the headset seem to lose sync with each other if you delay too long in making selections, cancel a session, or do much other than the steps I show above. (Remember it’s really a 0.99 release.)
  2. The duration reads “00” during the last 59 seconds of a session.

Update to my Free Guide to using the foc.us headset

I’ll be adding these instructions and more to my free guide in the next few days. I’d appreciate any input you have as the objective is to help headset users get the most from the product. The button to download the free guide is on the right side of my main blog page.

Not in the Box: The SpeakWisdom Guide to Using the foc.us tDCS Headset

If you own or plan to buy a foc.us tDCS headset, you may be interested in the guide to using the headset that I have posted.  The guide is an excellent walk-through of basic use and setup of this excellent product.  Whether your interested in improving memory, learning, performance on games, or relief from depression or chronic pain, tDCS may be right for you.  The foc.us headset provides a very capable, affordable way to give tDCS a try.


See the link on the right side of the main page of www.speakwisdom.com for your FREE copy of the guide.

I invite your comments and suggestions on the guide.



My tDCS Wish List

I have been reading studies, attending training, experimenting with, and writing about transcranial direct current stimulation (tDCS) for about two years now.  Needless to say, I am enthusiastic about what tDCS can do for many people who use it for depression, chronic pain, enhanced creativity, and memory. It may also may have positive effect for other important conditions such as stroke, Parkinson’s and Alzheimer’s – there are certainly studies that show that to be the case.

(Scientific American)

Given that it has positive effect on many who try it, it could improve the quality of life of millions of people around the world. All of this without drugs, without the cost of drugs, and with no significant side-effects.

With all the great things I’ve learned about tDCS, I thought I’d share a little of my tDCS Wish List for the next five years:

In The Next Five Years I Wish That:

  1. every appropriate medical practitioner (and counselor) would at least become aware of tDCS. A treatment this good, this simple, this safe, with so much positive effect should not be overlooked. It should be a tool in the kit of considered-treatments for every practitioner.
  2. that the popular press would at least make an attempt to write sensible and factual articles about tDCS. For example, it would be great to stop comparing tDCS to electro-shock treatment. Could they be any more different? Such mindless hype scares people who might be helped greatly by tDCS.
  3. that funding could be found to “get the word out” about tDCS. Because there are no drug company $ billions for magazine ads, TV commercials, and infomercials, it looks as though tDCS will always be a niche treatment, known by a lucky few – missed by millions it could help. I wonder how many lives could be vastly improved (or saved) if tDCS were as well-known as Viagra?
  4. that I could find one or more well-known, depressed, troubled Hollywood star(s), known for appearances in People Magazine and on TMZ – who would agree to a course of tDCS treatment. Once improved, those stars would have to be willing to speak about tDCS – the treatment that got them out of the pit. For better or worse, we live in a “star” powered society – such articles appearing in Hollywood rags and read and seen by millions could really help push tDCS towards a tipping point.
  5. that my second career be all about researching, writing, and speaking about the practical side of tDCS. There is a whole world full of people who need the help that this simple treatment can offer. A tDCS device can be as simple as a 9 volt battery, an inexpensive CRD diode, and a couple of sponges. Imagine the good that could be done!
  6. that I could find one or more philanthropists willing to join in the good work related to tDCS – and help a whole lot of people in the process! There are $ millions of research dollars flowing to universities and research centers all around the world looking at tDCS. But there is very little being done to get tDCS to the people who can benefit from it. If you are a philanthropist who really wants to make a difference in a very tangible way, feel free to contact me. Let’s get something started!

(One of the most important contributions of tDCS:
a simple treatment for the depression epidemic.)

Mark the date. At this point, for certain types of treatment, tDCS is well researched, simple, and considered safe. We all know that tDCS is barely known among the masses and the medical community. Ask any doctor you know  – I’d say the odds are about 1 in 100 that they know anything at all about tDCS.

What will things be like in 2018? By 2018, how many millions will have suffered for lack of access to a tDCS device and a tDCS trained professional? Can you help?

(A self-contained tDCS treatment headset. http://www.foc.us)

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 3 – Questions and Assorted Thoughts

(Feature laden and just plain cool! The foc.us tDCS headset.)

In this blog post, I’ll attempt to address some questions I have received as result of posting parts 1 and 2 of my review of the foc.us tDCS headset.  I’ll also pass along some editorial comments and tips.

General Comments

My wife and I have been using the headset for several days now.  We both find it easy to use and much less cumbersome than using a “traditional” tDCS device with a separate box, wires, and electrodes. The light-weight, secure fitting foc.us headset allows you to be very mobile as a session is underway.  Not having a box of some kind to tote around (along with a tangle of wires, headband, etc.) make tDCS sessions much less of a hassle.  Even if you use accessory wires on the foc.us headset, they attach to the headset so are out of the way.

The foc.us headset is a giant leap forward for the DIY market and probably will find its way into research-oriented and prescribed tDCS too.


OK, it’s not perfect.  Here are some annoyances and helpful tips.

  • Having the iOS app sure would help.  I hope it is approved by Apple soon!
  • The round sponges are only slightly larger than the sponge socket when wet.  It’s possible to knock them out while placing the headset on the head.  Plus, if you let the sponges fully dry repeatedly they tend not to expand quite as much when wet, so are more likely to fall out.
  • Perhaps storing the sponges in a small cup of water (with a mild disinfectant), so they never completely dry out will help extend their life?  I’m trying that now.
  • Suggestion: If you can find and adequate source for sponge material (I haven’t found a good match yet) cut your own. Make your sponges slightly larger than the original.  They don’t have to be round. Cut them square, then snip the corners of the square.  An eight sided sponge works fine.  Finding the right thickness is a challenge.
  • Will the headset fit any size/shape head? I can imagine not.  While the headset is flexible and probably will fit “average” heads, it is not fully adjustable.  Perhaps version two will better address “fit”. In case the current model just does not work for you, foc.us offers a 30 day money back guarantee.

(Wet vs. dry sponges. Don’t let them dry out if you can avoid it!)


Here are some questions I have received and my considered opinion:

  • Which “mode” should I use for treating various ailments?  The foc.us headset has four current delivery modes, sine-wave, constant current, pulsed, and random.  tDCS research is conducted using constant current DC and in my opinion, that is the mode that should be used unless you have specific recommendation from a physician or are conducting research in an appropriate setting.
  • How do you keep the external electrodes in place? The external electrodes are the sticky “TENS” style so will need a good skin area to attach.  I suppose it is possible to adapt the included wires to an “Amrex” type sponge electrode (so bands could be used), but I have not investigated that yet.
  • How long does the battery last? I don’t have an exact number, but it seems to last through many tDCS sessions before needing a charge.
  • Can you suggest various electrode placements? I’ve had this request from a number of people and will attempt to provide some guidance in my next post – including links to relevant research.
  • Have you found any “show stopper” issues with the foc.us headset? None so far.  It seems a solid product that may help bring tDCS to the world!  I’m anxiously awaiting the iOS app though!

(External electrodes are sticky TENS type.  Highly available and cheap.)

Coming in Part 4

Ok, ok, I got the message 🙂  You want more on electrode placement for various specific cases (depression, chronic pain, memory, savant learning, etc.)  My next post will provide as much information as possible on electrode placements.

Your questions and comments are always welcome. brent@speakwisdom.com