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.
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
- Small phillips screwdriver
- 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
The materials for this project should be obtainable from a hardware store or even a hobby store.
- Hot glue stick
- 9V Battery
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.
- Mouser parts****
- Hot glue stick
- 9V Battery
- 3.5mm plug electrode wires with 2mm pin connectors
- 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.
Step 1: Safety Glasses
Put on your safety glasses.
Step 2: Glue Gun
Plug in the hot glue gun
Step 3: Glue Stick
Insert a glue stick as far as it will go through the back hole of the hot glue gun.
Step 4: Battery Case
Remove the cover from the battery case which came in the Mouser order.
Step 5: Red Wire
The the RED wire into the battery enclosure or pull it from the inside with tweezers.
Step 6: Cut the Red Wire
Cut the red wires to 1" (25mm) measuring from the attached side.
Step 7: Strip Wire
Strip 1/4" (5mm) from the RED wire.
Step 8: Cut Component Leads
Cut the leads on the diode so each side has a 1/4" (5mm) wire.
Step 9: Helping Hands
Adjust the helping hands so the clamps are 1" (25mm) apart.
Step 10: Clamp Wire
Clamp the stripped RED wire into the Helping Hands.
Step 11: Clamp Diode
Clamp the diode so the lead opposite the BLACK band overlaps the stripped RED wire.
Step 12: Cut Solder
Cut a 3/4" (20mm) piece of solder.
Step 13: Wrap 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.
Step 14: Position Helping Hands
Position the Helping Hands unit so the solder wrapped parts hang over the edge of the table.
Step 15: Add Heat
Ignite the lighter a few inches (centimeters) below the solder wrap.
Step 16: Raise Lighter
Raise the lighter until it is 1/2" (12mm) below the solder.
Step 17: Extinguish Lighter
Remove the flame when the solder has melted.
Step 18: Unclamp Parts
Unclamp the diode and wire.
Step 19: Test Solder
Test the solder joint by tugging. There should be no wobble.
Step 20: Clamp Diode
Clamp diode so unsoldered end is between clamps.
Step 21: Clamp Red Wire
Place tinned end of RED wire in other clamp so it overlaps the unsoldered diode lead.
Step 22: Repeat 12-19
Repeat steps 12-19 to solder the RED wire to the other lead of the diode.
Step 23: Cut Shrink Tube
Cut a 1" (25mm) piece of shrink tube.
Step 24: Apply Shrink Tube
Put shrink tube over RED wire and diode so diode is centered under shrink tube.
Step 25: Clamp Wire
Clamp wire near shrink tube.
Step 26: Position Clamps
Positions clamps and shrink tube over edge of table.
Step 27: Start Lighter
Ignite lighter a few inches (centimeters) below shrink tube.
Step 28: Raise Lighter
Raise lighter while slowly waving back and forth across length of shrink tube.
Step 29: Extinguish Lighter
Release lighter when all portion of tube have shrunk.
Step 30: Rotate Tube
Rotate shrink tube if necessary and repeat steps 25 through 29.
Step 31: Unclamp Wire
Release the wire from the clamp.
Step 32: Fit Diode Inside
Position diode on switch cover inside 9V enclosure.
Step 33: Thread Red Wire
Feed RED wire back out enclosure hole.
Step 34: Glue Diode Down
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.
Step 35: Cool Glue
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.
Step 36: Test Switch
Ensure the switch can still operate.
Step 37: Test Cover
Ensure the cover can still close on the 9V enclosure.
Step 38: Cut Shrink Tube
Cut a 3" (75mm) piece of shrink tube.
Step 39: Insert Wires
Put RED and BLACK wires into shrink tube sleeve until the shrink tube is 1/4" (5mm) into the 9V enclosure.
Step 40: Glue in Place
Apply glue inside 9V enclosure to hole wires and shrink tube.
Step 41: Unplug Glue Gun
Unplug the hot glue gun and set it to the side where it cannot be accidentally touched.
Step 42: Optional Step
Use the lighter to shrink the tubing covering the RED and BLACK wires.
Step 43: Trim Wires
Trim the RED and BLACK wires to 1/4" (5mm) beyond shrink tube end.
Step 44: Strip Wires
Strip 1/8" (3mm) of insulation from each wire.
Step 45: Open Phone Socket
Open package with phone socket and select hollow metal piece
Step 46: Put Case on Wire
Put wires thought phone socket cover, unthreaded end first.
Step 47: File Phone Terminal
File backside of longest terminal in phone socket.
Step 48: Place Wire
Put stripped BLACK wire into post hole.
Step 49: Cut Solder
Cut 1/2" (12mm) piece of solder.
Step 50: Wrap Solder
Wrap solder around long post and exposed black wire.
Step 51: Clamp Post
Clamp post and BLACK wire together with RED wire bent away.
Step 52: Position Clamps
Position exposed wire, solder, and long post over edge of table.
Step 53: Repeat 15-19
Repeat steps 15 through 19.
Step 54: File Post
File rounded post with emery board.
Step 55: Bend Terminal
Bend square terminal away. It would also be acceptable to cut it off entirely.
Step 56: Clamp Socket
Clamp the rim of the phone socket.
Step 57: Position Wire
Position RED wire tip over the rounded terminal in the phone socket.
Step 58: Cut Solder
Cut a 1/2" (12mm) piece of solder
Step 59: Wrap Solder
Wrap solder around rounded post.
Step 60: Place Wire
Put RED wire under solder wrap.
Step 61: Position Clamp
Position exposed RED wire and rounded post over edge of table.
Step 62: Repeat 15-19
Repeat steps 15 through 19.
Step 63: Place Bundled Wire
Place bundled wires between crimp points of phone socket.
Step 64: Crimp Socket
Crimp phone socket onto wires.
Step 65: Secure Case
Screw the phone case onto the phone socket to finger tightness.
Step 66: Install Battery
Install the 9V battery.
Step 67: Install Cover
Replace the 9V battery enclosure.
Step 68: Secure Cover
Use the supplied screw and screwdriver to tighten the screw into the cover.
Step 69: Switch On
Flip the 9V switch to the ON position.
Step 70: Test Short Circuit Current
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:
- check the power switch to make sure it is on.
- check the 9V battery has a charge.
- verify the meter is working properly.
- check the polarity of the diode.
Step 71: Electrolyte Solution
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.
Step 72: Place 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.
Step 73: About Me
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.