Brain Cortices Info Graphic

Welcome to the Transcranial Direct Current Stimulation FAQ page! Compiled here are the questions most frequently presented to us by those interested in tDCS. We’ve tried our best to answer each question in a straightforward, yet comprehensive manner. We are continuously adding more questions, and updating our answers, to ensure this FAQ contains the most relevant up-to-date information as possible.

Can’t find what you’re looking for in our tDCS FAQ? Just submit your question using the form at the bottom of this page and we’ll try to answer it to the best of our ability. If your question is a good one, we may add it to this page and even give you credit!

However, if you need an immediate answer to your question, we still suggest sending us a message.



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tDCS can often be confused with TMS due to the similarity of their names. In addition, tDCS and TMS can produce similar results depending on their specific use.

TMS (Transcranial Magnetic Stimulation) is the process of passing large magnets near a person’s scalp in order to generate a magnetic field that stimulates neurons in the brain. Similarly tDCS (Transcranial Direct Current Stimulation) stimulates neurons, but instead uses low levels of electric current. In addition to being cheaper more convenient, tDCS can produce a myriad of results that haven’t been recorded using TMS. Since tDCS is applied directly to the scalp using electrodes, many individuals experience more direct, stronger, and longer lasting effects.

Usually an individual must undergo a mental health evaluation and obtain a prescription before undergoing TMS. Often times the prescribing facility will offer TMS treatment in their office. TMS involves large machines that can occupying an entire room. During treatment, the patient must remain physically still in order for the machine to target a specific area.

Alternatively, tDCS devices are often compact, hand-held units that can be carried anywhere. The person using tDCS is not required to sit still, and depending on the case may even be able to complete their sessions in the comfort of their own home. tDCS and TMS are not interchangeable, and many factors are involved in the process of treatment. TMS is currently FDA approved for a small number issues such as Major Depressive Disorder, OCD, and

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tCS – Transcranial Stimulation (aka) tES – Transcranial Electrical Stimulation
The acronyms tCS and tES (often used interchangeably) are used to describe any therapy in which electricity is applied on or through the cranium. In comparison to all of the types of cranial stimulation listed below, it is generally understood by most that tDCS is safer, more comfortable, easier to engage in, more affordable, and will often produce a more robust response. However it is important to note that new theories and opinions on the different forms of tCS/tES are being developed on an ongoing basis.

tACS – Transcranial Alternating Current Stimulation 
During tACS, very low levels of alternating current are applied to the brain, usually via a set of non-invasive electrodes placed on the head. Alternating current is different from direct current in that electrical current periodically reverses direction, taking the graphical form of a sinusoidal shape.  Amplitude, frequency and relative phases across stimulation electrodes can be controlled. tACS and it’s effect on the brain is currently the subject of an active research field in basic and clinical Neuroscience.

tRNS – Transcranial Random Noise Stimulation
A new form of transcranial electrical stimulation, first tested in 2008 at a public research University in Göttingen, Germany. Like tACS, tRNS uses oscillating current, with the distinction being tRNS utilizes random amplitude and frequency. While this stimulation method is still very new, it is hypothesized that tRNS’s effects are mainly excitatory, and that higher frequencies may produce greater results.

Graphical Representation of tDCS tACS and tRNS current wave forms

TENS – Transcutaneous Electrical Nerve Stimulation
Usually used in muscle therapy and not intended for use on the cranium. Transcutaneous is defined as existing, applied, or measure across the depth of the skin.

CES – Cranial Electrotherapy Stimulation
Applies a small, pulsed (AC) electric current across a patient’s head to treat anxiety, depression, insomnia and chronic pain. The term CES is often used interchangeably with tACS to refer to the same type of device.

TMS – Transcranial Magnetic Stimulation
Utilizes magnetic fields to stimulate nerve cells in the brain, and is usually used to treat depression in patients where other therapies have proven ineffective. TMS can be very particular and should only be performed by a qualified technician. To learn more about TMS and rTMS (Repetitive Transcranial Magnetic Stimulation), see our Brain Stimulation Comparison page.

ECT – Electroconvulsive therapy, or “shock therapy”
Made familiar to the public through a scene in the 1975 film, One Flew Over the Cuckoo’s Nest. ECT utilizes a current incredibly larger than most forms of cranial electrical stimulation (around 600-1000 milliamps), and is applied to the entire brain, often via the temples. This form of therapy usually results in a controlled grand mal seizure and must be done under general anesthesia. Because ECT produces significant side effects, including memory loss and confusion, it is only used for patients with severe, treatment-resistant depression, and even then it is used as a last result measure. To learn more about ECT, see our Brain Stimulation Comparison page.

Brain Stimulation Techniques Graphical Comparison

A fantastic comparison of tDCS, tACS, tRNS, and tACS from the July 2014 book, The Stimulated Brain – Cognitive Enhancement Using Non-Invasive Brain Stimulation (Page 38, Figure 2.1) edited by Roi Cohen Kadosh.







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Yes!! Currently we offer two International Shipping options; Standard International and Express International. For your convenience, we’ve added a shipping calculator to our Cart Page. To obtain shipping costs for your destination, proceed to the Shop Page and add the items you’re interested in to your cart. Once finished, proceed to the cart page and enter you location information into the calculator in the “Cart Totals” section of the page.

We’ve shipped our tDCS devices to nearly 100 different countries over the course of being in business. Some of the most popular International shipping destinations we’ve shipped our tDCS products to include:

  • Canada (CA)
  • Australia (AU)
  • Brazil (BR)
  • United Kingdom (GB) – AKA the UK
  • Sweden (SE)
  • Turkey (TR)
  • India (IN)
  • Germany (DE)
  • Russia (RU)
  • Belgium (BE)
  • France (FR)
  • Czech Republic(CZ)
  • Norway (NO)
  • Spain (ES)
  • Taiwan (TW)
  • Austria (AT)
  • Italy (IT)
  • Lebanon (LB)
  • Denmark (DK)
  • Republic of (South) Korea (KR)
  • Hong Kong (HK)
  • New Zealand (NZ)
  • Netherlands (NL)
  • Chile (CL)
  • Finland (FI)
  • Japan (JP)
  • Poland (PL)
  • Singapore (SG)
  • Estonia (EE)
  • Greece (GR)
  • Hungary (HU)
  • Thailand (TH)
  • Switzerland (CH)

This is not an exhaustive list by any means, so if you live there, we probably ship there.

Should you have any shipping questions regarding your destination, please feel free to contact us directly.

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We manufacture all our tDCS devices in sunny Southern California. Additionally, the majority of the resale products we carry, such as Amrex Sponge Electrodes, are manufactured in California as well! In regards to our products; if it’s not made in California, it’s made somewhere else in the United States. If it’s not made in the United States, WE DON’T CARRY IT.

By working with domestic companies we are able to build close working relationships with our vendors, and provides many benefits such as faster shipping and restocking times, as well as the ability to closely manage our quality control processes, which results in higher-quality products with unmatched performance.

Doing business with local vendors has been an integral part of our value proposition from day one, and helps differentiate us from our competitors. Our ability to walk through the door of any number of our local vendors, shake their hand and sit down across the table from them, is something we’ve found absolutely invaluable. By choosing to purchase from and work with domestic companies, we’re doing are part to help create jobs right here in United States.

Additionally, we do all of our order fulfillment in house, so every purchase gets shipped to you straight from our California offices. Furthermore, we’re working hard to expand our International business, and hope to open up overseas shipping facilities in the near future. In the meantime, we offer several International shipping options such as:

  • USPS First Class International
  • USPS Priority International
  • USPS Priority Express International
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We currently accept Credit Card and PayPal payment methods. All payment information is fully encrypted and handled by third party payment processing companies (Stripe or PayPal). By using third party payment processors, we ensure your data is kept protected and secret, as we never see or save any of your sensitive payment information.

To pay via credit card, simply fill out your billing, shipping, and credit card information on our Checkout page, or select the “Checkout with PayPal” option located just below the Stripe form and click “Proceed to PayPal”.

If you wish to skip our billing & address forms and checkout faster, then we suggest using PayPal Checkout. You do not need a PayPal Account to checkout via PayPal, nor will you be required to create one if you choose this checkout method. If you do not have a PayPal account, there is a link at the bottom of the PayPal checkout webpage which instructs you on how to complete the transaction.

You can find the PayPal checkout option on our Cart page, at the top and the bottom of our Checkout page, as well as on some product pages (example: The Brain Stimulator tDCS Kits). Once you click a PayPal checkout button, a PayPal pop up window will appear which will guide you through the short and simple payment process. When finished, you will be redirected back to our website to confirm your order details and complete the transaction.

If you have any further questions regarding payment or if you encounter any errors, please contact us directly.

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The technology in our devices actually doesn’t utilize Frequency. Frequency is the number of occurrences of a repeating event, within a specified unit of time. Hertz is a unit of Frequency used in the International System of Units to represent one cycle per second. Hertz is often used to measure Alternating Current. In the field of Cranial Electrical Stimulation, Alternating Current is used in tACS devices (Transcranial Alternating Current Stimulation). Devices such as ours that utilize tDCS (Transcranial Direct Current Stimulation) utilize Direct Current, which is essentially the opposite of Alternating Current, in that it doesn’t oscillate (or repeat) and remains consistent.

Electrical Direct Current vs Alternating Current Visual Wave Forms






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These flashes of light are quite common when using transcranial electrical stimulation, and are known as phosphenes. Usually this will happen when an electrode is placed near the eye, and is a result of current running across optic nerves. While it may seem scary at first, this phenomenon has been recognized and studied by the scientific community and is understood to be a harmless side-effect of tDCS. Phosphenes can be reduced or even prevented completely by moving the electrodes further away from the eyes. More can be read about TES and Phosphenes in this PubMed Article.

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It’s actually fairly common for individuals using well soaked sponge electrodes to not feel much of anything when engaging in tDCS. Sometimes you may  notice a sensation when first turning on the device, which may fade away over the course of the session. This is due to the cells in your body aligning to allow the current to pass through with less resistance. Additionally, we’ve found that over time the body becomes less sensitive to the feelings associated with tDCS. If you’ve been using tDCS for some time and no longer feel anything, even when replacing the battery, it’s very possible that you’ve just become used to the sensations. We can assure you that there is little to no possibility that your device has “gone bad” as we have individuals who have been using our products for years and still experience all of the wonderful effects that can be associated with tDCS.

If you’re still suspicious that maybe your device isn’t producing current, there’s a simple way that you can test to ensure current is flowing. Install a new battery in your device and remove any electrodes or adapters from the electrode lead wires. While this next part may sound a little weird, it’s completely harmless. Turn the device on and to the lowest setting, and lightly lick the two electrode leads with your tongue. You should feel a slight tingle on your tongue (less than the sensation of licking a 9 volt battery, if you ever did that as a kid).

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We recommend using Alkaline disposable 9V batteries for use in our tDCS devices. Alkaline 9V batteries are the standard, over-the-counter batteries which can be purchased at almost any store that carries batteries. Common brands include Duracell, Energizer, Rayovac and others. Out of the various brands of Alkaline 9V batteries available, we personally recommend Duracell’s Procell brand Alkaline 9V Batteries. This is the only battery that we personally use, and the only battery that we stock in our online store. There are several different factors why we recommend this type and brand of battery such as longevity, reliability, power, and affordability. More information on Duracell Procell 9V batteries can be found on the product’s listing page.

Regardless of the brand of battery you choose, we strongly recommend not using rechargeable batteries for tDCS. One reason for this is that these batteries are rarely charge to the full 9-volts, which prevents the user from effectively engaging in tDCS montages where electrodes are father apart. Essentially, the higher the voltage, the more effective the battery is at passing current over farther distances.

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We no longer recommend using self-adhesive electrodes with tDCS. The reason we do not recommend self-adhesive is due to the fact that they do not conduct current as well, or as evenly as sponge electrodes. Due to the way self-adhesive Electrodes are manufactured, there’s often a high potential for current to collect, or concentrate, on a specific location on the electrode’s surface. This concentration of current creates what’s known as a “Hot Spot,” causing high current density which can result in an uncomfortable session, or even skin irritation. While Hot Spots do not always happen, sponge electrodes are by far the safest and most effective option for use with tDCS. Additionally, you can further practice “safe-tDCS” by always using an electrode positioning headband(s) (we offer small and large tDCS headbands), to ensure that the entire electrode makes contact with the targeted area.

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Essentially the main difference between the 3×3″ Sponge Electrodes and the 2×2″ Sponge Electrodes is the size of the electrode pad and the area they cover. They both are constructed in exactly the same way, with the same materials and use the same Amrex electrode cables and adapters. The 3×3″ electrodes will cover a broader area, while the 2×2″ will cover a slightly smaller, more condensed area. Essentially the 2×2″ sponge electrodes will stimulate a more targeted area, while the 3×3″ have more of a generalized effect on the area being stimulated. Additionally, because of the larger surface area, the 3×3″ size generally provides a more comfortable session with fewer negative side effects. Due to these facts, the 3×3″ size sponge electrodes are far more popular than their 2×2″ counterpart.

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tDCS electrode sponges can be replaced every two weeks or after seven tDCS sessions. However, for optimum performance and hygiene reasons, we recommend replacing your sponges after each session. Replacement sponges for 2×2 and 3×3″ electrodes can be purchased in packs of 10 in our online store. In addition, due to customer requests we now offer replacement sponges in subscription plans at discounted pricing.

Over time, the sponges within sponge electrodes can grow brittle and crumble, crack, or split, causing an uneven distribution of current. Worn-out sponges can cause an uncomfortable tDCS session, with increased tingling, itching, and sometimes stinging sensations occurring. A good way to tell if your sponges need replacing is if soaking them with saline solution becomes more difficult, if they start to display a darker/brownish color, or begin feeling “stale.”

More importantly, if your tDCS sessions become uncomfortable, or you start to notice sensations that maybe you didn’t before, this is a good sign that your sponges need replacing. You can find 10-packs of replacement sponge inserts for both the 3×3″ Amrex Electrodes and the 2×2″ Amrex Electrodes in our online store.

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While saline solution is not strictly required for use with sponge electrodes, it is recommended. Plain water will work in helping the sponge to pass current, just not as well as saline solution. Water in and of itself is a very poor conductor of current. So in using just water, you’re essentially asking the sponge alone to work to pass current to the targeted area. By adding salt to plain water (saline solution), the electricity is able to actually jump from molecule to molecule through the solution, providing a better connection. In using a sponge well soaked with saline solution, the current encounters the least amount of resistance, providing the most effective, and most comfortable tDCS experience.

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Saline solution refers to the mixture of NaCl sodium chloride, aka salt, and water. Saline solution is commonly used in medicine to cleanse wounds, treat dehydration, and cleanse and preserve contact lenses. Non-invasive brain stimulation techniques like transcranial direct current stimulation (tDCS) utilize sponge electrodes to apply current to targeted brain regions. Sponges are used because when wetted they allow current to flow through any hair located on the head. Since water by itself isn’t a great conductor of electricity, it is best to use a saline solution to ensure that current reaches the cranium with the least amount of resistance.

Saline solution can easily be made at home using tap water and standard table salt. The optimal concentration of salt for use with transcranial stimulation is 0.9%.  This equates to approximately 2.3 grams of salt per a standard 8oz glass of water. For convenience, we sell a Saline Solution Applicator Bottle which includes accurate mixing instructions printed right on the bottle. This 2oz pointed-spout squeeze bottle makes it incredibly easy to apply saline solution directly, and evenly across the sponge electrodes. Furthermore, the liquid seal cap means you can travel with your saline solution, even while flying as it complies with all TSA travel guidelines!

The Saline Solution Applicator Bottle comes included with every Deluxe tDCS Kit, or can be purchased individually through our online store.

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Our goal is to produce tDCS devices of the highest quality standards, which operate with precision and guaranteed accuracy, therefore we do not include current meters in our products. Analog current meters are incredibly inefficient, and are only required for tDCS devices which do not have proper voltage/current control and adaptation circuitry in place.

The Brain Stimulator tDCS devices include enhanced circuitry comprised of precision components, integrated circuits, and microprocessors (“smart” technology) which control and monitor current and voltage levels several times a milliseconds. Through the use of these special technologies, and by nature of design, our products do not require the user to monitor current flow. However, tDCS devices which use rudimentary circuitry must include a current meter, as the user must constantly monitor and adjust the output flow in order for the device to produce accurate current.

In some ways this can be compared to manual (stick shift) cars versus automatic cars. With a manual gear shift automobile, the drive must constantly monitor the state of the automobile to know when he or she needs to change gears (adjust the device). However, cars which utilize automatic shifting do not require the constant attention of the driver as the technology within the car “adjusts” (shifts) itself at the optimal time.


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General consensus suggests that standard tDCS sessions can last anywhere between 5 to 30 minutes, with the most common professional research sessions lasting 20 or 30 minutes in duration. Clinical research has found five minutes to be the minimum stimulation duration required to produce notable effects which last beyond the conclusion of the session, and that sessions lasting 20 to 30 minutes often  produce the best results1.


1 Nitsche and Paulus, 2000, Nitsche and Paulus, 2001, Nitsche et al., 2003

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YES! Our products use the same technology (transcranial direct current stimulation) as the Halo Sport headphones. The only difference between The Brain Stimulator and Halo Sport (other than price), is The Brain Stimulator provides the user with the flexibility to position the electrodes in multiple arrangements.

The incredible thing about tDCS is that different electrode placements (referred to as “montages”) can produce different results. The Halo Sport headphones utilize fixed electrodes, which are located on the headphone’s bar, placing them directly over the primary motor cortex. While this may be convenient for those who wish to use tDCS for solely for muscle memory, this limits the user them from exploring other placement positions.

We took a different approach and manufactured The Brain Stimulator with free standing electrodes which can be placed anywhere the user desires. From the very beginning, we have always maintained the belief that the customer should be allowed to use tDCS in any manner they so choose and that to limit the customer would be to limit self exploration and creativity.


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Fisher Wallace produces products that are quite different from The Brain Stimulator family of tDCS devices. While The Brain Stimulator utilizes tDCS (Transcranial Direct Current Stimulation), the Fisher Wallace Stimulator utilizes tACS (Transcranial Alternating Current Stimulation). Studies have shown that tDCS and tACS are both generally considered safe and effective methods of non-invasive brain stimulation1. However, at least one study found that tACS did not appear to create significant changes in cortical excitability2, whereas numerous studies have documented tDCS’s ability to modulate cortical excitability both during and after stimulation 3, 4.


In addition, tDCS has the ability to either increase (via Anodal stimulation) or decrease (via Cathodal stimulation) the spontaneous firing rate of neurons in the brain56. This duality of effects can be seen in various scientific studies where researchers may focus on increasing desired results (such as improving cognition7), while through alternative tDCS montages, decrease others (such as chronic pain8).


While many people believe the Fisher Wallace Stimulator is FDA approved, this is not the case. Rather, The Fisher Wallace Stimulator is only FDA cleared. While much progress has been made over the years to gain FDA approval, in the field of brain stimulation there are currently no tES (Transcranial Electrical Stimulation) devices which have been granted approval. This does not mean brain stimulation devices are deemed unsafe by the organization, but rather that it has not yet been determined to what classification, standards, or methods of approval, this new industry should conform to.


Interested in learning more? Check out “What is tDCS?” or read more about The Brain Stimulator v3.0.


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Reported tDCS side effects are very few, and only experienced by a small number of the population. Some side effects associated with tDCS include a tingling or itching sensation during stimulation, a slightly metallic taste, and occasional redness at the site of the electrodes. Any redness usually fades away shortly after stimulation. An even smaller percentage of the population reports a slight headache as a tDCS side effect, however this also usually subsides shortly after the session is concluded. The most least reported tDCS side effect, which is usually attributed to improper use of electrodes or poorly assembled/prepared electrodes, is skin irritation. Sometimes this irritation can take the form of a small skin bump or lesion. However, it is important to note that even this side-effect is quite minor, and will fade away over a short period of time.

tDCS Side effect organized into an informational graphicWe found a great infographic on tDCS side effects located at, which shows that often most side effects can be attributed to the placebo effect. The results shown below depict that based on clinical trials, those individuals receiving “sham” stimulation (fake, no current) often reported the same symptoms at similar severity levels compared with those individuals receiving active stimulation (real tDCS).

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The feelings experienced during a typical tDCS session can vary from individual to individual, and can be based on several factors such as as the montage (electrode placement) being used, level of current, and length of the session. The most common sensation associated with tDCS is a slight tingling, itching, or “warming” sensation felt at the source of the electrodes. This sensation can often be suppressed by applying additional saline solution, or by applying slight pressure to the sponge electrodes to help saturate the area. Adding additional saline solution usually requires stopping the session and removing the electrodes, however saline can be applied easily and comfortably during a tDCS session by using a saline solution applicator bottle.

In addition the the above, some individuals claim to experience a metallic taste in their mouth, but usually report it to be temporary and only during the start of the session. Sometimes it is possible to experience the appearance of a very flash of white light, however this is very rare and only possible if the device being used does not feature “ramping,” and the electrodes are positioned near the optical nerve (near the eyes). Almost all of the tDCS devices being produced by reputable companies feature this technology. The Brain Stimulator v3.0 features internal current stepping, which another form of ramping technology which results in an incredibly comfortable tDCS session.

Overall, most people describe tDCS as being a relatively positive experience, and some report not feeling anything at all!

For some related information, check out: Are there any side effects associated with tDCS?

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Not to worry, we’ve got your back! While tDCS can be confusing at first, it’s really fairly simple and straight forward. First and foremost, we recommend that anyone interested in tDCS read through this FAQ page. We spent a significant amount of time researching and compiling these Q&A’s in hopes that it helps individuals like yourself in your quest to learn more about tDCS. We are always looking to improve this FAQ, so if you can’t find the answer to your question, please submit it at the bottom of this page!

Secondly, you may want to take a look at our “What is tDCS?” page. While you may find some of the information redundant, we’ve attempted to present information on tDCS in a more straight forward and easy to understand manner. Finally, we also recommend reading through Dr. Brent Williams Blog on tDCS, and if you’re looking for information on electrode placements, try This should get you well on your way to understanding more about tDCS.
*Please note that we do not take responsibility for content located on external websites.

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