TDCS Thinking Cap

tDCS is an abbreviation for Transcranial Direct Current Stimulation which is a form of neurostimulation which uses constant, low current delivered directly to the brain area of interest via electrodes. It was originally developed to help patients with brain injuries such as strokes but has shown great success on tests with healthy adults. It has been utilized to enhance language and mathematical ability, attention span, problem solving, memory, and coordination.

This is done by positioning electrodes on the head and body then passing a carefully regulated current through the electrodes. 20 minutes is the usual recommended time limit. I can't stress how important it is to research for your own safety. Placing the electrodes in the wrong place could have an unwanted effect but I have never seen anything more than inconvenience and forgetfulness. This stopped immediately when the power was removed. I personally experience a metallic taste in my mouth but this is common.

This set of instructions was designed to be accessible to people of all skill levels and will hopefully encourage more people to try tDCS without breaking the bank. Each step has a single picture and a simple instruction so completing the project is a matter of following each step to the letter. This guide does not have instructions for electrode placement which is a field all its own and the tDCS Placements does a better job than I could.

Tools

This was designed to be built during a workshop where all tools have been provided and a minimal cost and traditional soldering skills were not needed. For example, the directions show that I used nail clippers to cut and strip wire but if you have a wire stripper go ahead and use it. A lighter is used to melt ordinary solder however traditional soldering skills can easily be applied.

I've taken a picture of most of the tools used in this project and they cost less than $20. The cost goes under $10 if you build your own helping hands or already own a set.

• Safety glasses
• Nail clippers*
• Emery board**
• Hot glue gun
• Tweezers
• Small phillips screwdriver
• Lighter***
• Ruler
• Helping Hands (not pictured)
• Millammeter, often selectable on a multimeter

* A wire stripper may be used instead

** A rasp or sandpaper may be used instead

*** A soldering iron may be used for some of the steps where a lighter is used

Materials

The materials for this project should be obtainable from a hardware store or even a hobby store.

• Solder
• Hot glue stick
• 9V Battery

Parts

The parts for this project are minimal. Great effort was taken to find inexpensive shipping and suppliers with readily available parts so that this project can be reassembled for many years.

1. Mouser parts****
2. Solder
3. Hot glue stick
4. 9V Battery
5. 3.5mm plug electrode wires with 2mm pin connectors
6. Electrodes with 2mm pin connectors

***Mouser makes it very simple to order a set, or multiples, of parts for this project. 1, click the link, click "Order Project." You now have the necessary parts in your shopping cart.

Put on your safety glasses.

Plug in the hot glue gun

Insert a glue stick as far as it will go through the back hole of the hot glue gun.

Remove the cover from the battery case which came in the Mouser order.

The the RED wire into the battery enclosure or pull it from the inside with tweezers.

Cut the red wires to 1" (25mm) measuring from the attached side.

Strip 1/4" (5mm) from the RED wire.

Cut the leads on the diode so each side has a 1/4" (5mm) wire.

Adjust the helping hands so the clamps are 1" (25mm) apart.

Clamp the stripped RED wire into the Helping Hands.

Clamp the diode so the lead opposite the BLACK band overlaps the stripped RED wire.

Cut a 3/4" (20mm) piece of solder.

Wrap solder around touching leads.

It may be easier to curl the solder into a small helix and put the wires into the solder helix.

Position the Helping Hands unit so the solder wrapped parts hang over the edge of the table.

Ignite the lighter a few inches (centimeters) below the solder wrap.

Raise the lighter until it is 1/2" (12mm) below the solder.

Remove the flame when the solder has melted.

Unclamp the diode and wire.

Test the solder joint by tugging. There should be no wobble.

Clamp diode so unsoldered end is between clamps.

Place tinned end of RED wire in other clamp so it overlaps the unsoldered diode lead.

Repeat steps 12-19 to solder the RED wire to the other lead of the diode.

Cut a 1" (25mm) piece of shrink tube.

Put shrink tube over RED wire and diode so diode is centered under shrink tube.

Clamp wire near shrink tube.

Positions clamps and shrink tube over edge of table.

Ignite lighter a few inches (centimeters) below shrink tube.

Raise lighter while slowly waving back and forth across length of shrink tube.

Release lighter when all portion of tube have shrunk.

Rotate shrink tube if necessary and repeat steps 25 through 29.

Release the wire from the clamp.

Position diode on switch cover inside 9V enclosure.

Feed RED wire back out enclosure hole.

Put a thin layer of hot glue over and around diode. Use as little as possible because large gobs can gum up the switch or keep the cover from fitting properly.

Allow the glue to cool for 10 seconds or so.

This is the halfway point in the instructions and maybe a good time for a break.

Ensure the switch can still operate.

Ensure the cover can still close on the 9V enclosure.

Cut a 3" (75mm) piece of shrink tube.

Put RED and BLACK wires into shrink tube sleeve until the shrink tube is 1/4" (5mm) into the 9V enclosure.

Apply glue inside 9V enclosure to hole wires and shrink tube.

Unplug the hot glue gun and set it to the side where it cannot be accidentally touched.

Use the lighter to shrink the tubing covering the RED and BLACK wires.

Trim the RED and BLACK wires to 1/4" (5mm) beyond shrink tube end.

Strip 1/8" (3mm) of insulation from each wire.

Open package with phone socket and select hollow metal piece

Put wires thought phone socket cover, unthreaded end first.

File backside of longest terminal in phone socket.

Put stripped BLACK wire into post hole.

Cut 1/2" (12mm) piece of solder.

Wrap solder around long post and exposed black wire.

Clamp post and BLACK wire together with RED wire bent away.

Position exposed wire, solder, and long post over edge of table.

Repeat steps 15 through 19.

File rounded post with emery board.

Bend square terminal away. It would also be acceptable to cut it off entirely.

Clamp the rim of the phone socket.

Position RED wire tip over the rounded terminal in the phone socket.

Cut a 1/2" (12mm) piece of solder

Wrap solder around rounded post.

Put RED wire under solder wrap.

Position exposed RED wire and rounded post over edge of table.

Repeat steps 15 through 19.

Place bundled wires between crimp points of phone socket.

Crimp phone socket onto wires.

Screw the phone case onto the phone socket to finger tightness.

Install the 9V battery.

Replace the 9V battery enclosure.

Use the supplied screw and screwdriver to tighten the screw into the cover.

Flip the 9V switch to the ON position.

Plug into a mA testing unit or connect the electrode wires and measure the short circuit current. The reading should be less than 2.5mA.

If no current is seen:

1. check the power switch to make sure it is on.
2. check the 9V battery has a charge.
3. verify the meter is working properly.
4. check the polarity of the diode.

Mix up some warm salt water. Ordinary table salt + ordinary tap water. The salt acts to make the solution more conductive and use warm water so it isn't chilly when it touches your skin.

Most electrodes have a cotton coating which will hold some water. In my case the carbon-rubber electrodes needed a felt sleeve. Do not use a carbon-rubber electrode without a sleeve.

Apply salt water to the electrode until it is saturated.

Make sure the tDCS switch is OFF.

Put the electrode pins into the sockets of the electrodes.

Here is the most basic placement of tDCS electrodes. Electrode places are also called a montage. More can be found here. The anode (RED) electrode goes on the head 2" (50mm) above the right temple. The cathode (BLACK) electrode goes on the left upper arm.

Turn the tDCS switch to ON.

If there is a strong pinching sensation at the electrode site add more salt water.

You may experience a metallic taste, I do.

You may experience an ability to learn faster, which is the goal. Test yourself with online IQ tests.

Turn the device off after 20 minutes. Do not use for more than 20 minutes in a day or you may experience headaches. Do not sleep with this device on.

Conduct research into this procedure and follow all warnings. This Instructable is about building the device rather than using it. You must perform your own research but there is plenty of source material and people eager to share their findings.

I spend days trying to source parts for this project and that took much MUCH longer than actually assembling it. If you read my blog you will know that this is the second iteration which was built from the exact parts I called out for the Mouser order so that everything would be clear. The first version was more cobbled together but the electrical design is rugged so there are no problems with it.

If this device becomes popular I have some plans for modules which would attach in series to expand the capabilities including a meter, an adjustable current module, and timer, and a switch to cut power if you fall asleep while using this.

As mentioned I run a blog where I talk incessantly about the things I build, including an unabridged version of this projectwith pictures of the first unit as it was being assembled. There are other neat things there like the mA testing box shown in step 70 and an ADJUSTABLE current tDCS unit I slapped together in an Altoids tin.