Easy to Build 40 Hz Gamma Wave Flashing LED Lamp

According to an artcle in the December 8, 2016 issue of the journal Nature, an
LED light that fashes at 40 Hz, which is the frequency of Gamma wave in the
brain, may alleviate the symptoms of Alzheimer's disease. Also, a 40 Hz
fashing LED light is said to be an aid to meditaton.

In this artcle, I will describe an easy way to build a 40 Hz fashing LED foor
lamp. About all you need to know is a litle bit about electricity that you probably
learned as a kid, and a litle bit about household wiring, such as how to replace
an electrical outlet in the wall of your home.

The parts you will need
1. A DROK LCD Display Square Wave Generator,

Price on Amazon: $11.20.

2. A DC solid state relay,
Digi-Key part number CC1126-ND. Price on Digi-Key: $20.20.

3. A 12 volt DC power supply, such as this one on Amazon:

Price on Amazon: $13.99.

4. Two 12 volt LED light bulbs, such as this one on Amazon:
Price on Amazon: $15.98.

5. Dual light bulb socket, such as this on Amazon:
Price on Amazon: 6.99.

6. Two to six foot extension cord. Available at a local hardware store.

7. Twist-on wire connectors, such as these on Amazon:
Price on Amazon: $2.07.

8. A standard foor lamp.

9. #22 gauge hook-up wire, such as this on Amazon:
Price on Amazon: $18.95.

10. Soldering iron and solder. Soldering the connectons to the DROK Square Wave Generator is preferable but not absolutely nessesary. If you don’t solder the connectons, strip about V/8ths of an inch of insulaton of the ends of hook-up wires and loop them through the connectng holes in the DROK in twist-tie fashion, and twist tghtly.

Putting it together
1. Connect the negatve wire from the power supply to “VIN –” (the negatve input) on the DROK square wave generator.
VIN -” is internally connected to GND on the output terminal screw #1 (the positve output) on the solid state relay.

2. Cut the extension cord at a convenient length, measured from its socket end.

3. Connect terminal screw #4 (the negatve input) on the solid state relay both to the Neutral (wide slot) side of the extension cord socket AND to GND on the output side of the output side of the DROK square wave generator.

4. Connect the positve wire from the power supply both to “VIN +” (the positve input) on the DROK square wave generator AND to terminal screw #1 (the positve output) on the solid state relay.

5. Connect terminal screw #2 (the positve input) on the solid state relay to PWM on the output side of the DROK square wave generator.

6. Connect terminal screw #2 (the negatve output) on the solid state relay to the HOT (narrow slot) side of the extension cord socket.

7. Turn the foor lamp off, unplug it, and screw the dual light bulb socket into its socket. Screw in the two 12 volt LED light bulbs.

8. Read the instructons that came with the DROK square wave generator.

9. Plug the power supply into the wall and set the DROK to 40Hz and the duty cycle to 50%.

10. Plug the lamp into the socket of the extension cord.

11. Turn the foor lamp on and it should now be fashing at 40 Hz! If you like, you can experiment with other frequencies and duty cycles.

24 thoughts on “Easy to Build 40 Hz Gamma Wave Flashing LED Lamp

  1. Very very cool! Sure wish I could figure this out but the circuit diagram is greek to me. Actually I understand some Greek. Can someone w no experience make this? Thanks!

    • Yes, and it works just fine.  I have it’s LED array sitting on my desk,
      happily flashing. Perhaps the easiest way to test and adjust its
      frequency is by using an oscilloscope. I’m not sure, but I think there
      are free desktop software versions of oscilloscopes, which use the
      microphone input your computer likely already has, for input. 
      Otherwise, you could just use the values I have in the circuit, and
      that should be close.  But all component have a tolerance — accurate
      only to within a small percentage, so YMMV.

    • Yes, that’s the LED array I used.  There would be no point
      in providing a picture of the circuit, because the circuit
      diagram provides far more information than a picture
      would provide.

  2. Thanks for the info! I’m planning on making my own circuit using your plans. I’m no expert but I believe your circuit diagram should show the threshold and trigger pins tied together. Thanks again!

  3. Hi! Thank you for sharing your work!
    I’m tinkering with 555 driven flashing LEDs myself due to this article in Nature about “non-invasive 40 Hz light-flickering regime that reduced Aβ1–40 and Aβ1–42 levels in the visual cortex of pre-depositing mice and mitigated plaque load in aged, depositing mice. Our findings uncover a previously unappreciated function of gamma rhythms in recruiting both neuronal and glial responses to attenuate Alzheimer’s-disease-associated pathology.” (i.e. 40Hz light at 473nm wavelength reducing symptoms of Alzheimer’s).

    Do you think you are getting 473 nm light with your version?

    • The authors used two different methods for the 40 Hz gamma
      frequency entrainment.  First, they directly stimulated the
      brains of the mice by inserting into their brains a fiber that
      carried 473nm blue laser light pulsing at 40 Hz.

      Second, the authors put the mice into cages and placed nearby
      them an array of white LED lights flashing at 40 Hz. This can
      be seen in Supplementary Video 4, referred to in their Nature
      article.  Here’s a link to the video:


    • I downloaded the app onto my iPad.  It seems to be very inaccurate.  The app measured beteeen 55 and 60 Hz on my circuit,  I re-checked the frequency with my oscilloscope and its reading was 40.1 Hz.  I have no reason to doubt the oscilloscope, because the wave it displays is almost perfectly rectangular.


  4. Hi Bob,
    I would like to build your circus. Most of the links in your instructions are no longer active. Could you please update? Also, did I read there is also a circuit diagram. I don’t see in your links. Your help is much appreciated.

    • Hi Hisham,

      Thanks much. I have now updated all of the links. 
      I think I checked all of them pretty well, but please
      let me know if any of them don’t work.

      — Bob Day

  5. The Bobday design worked great for me. I mounted everything in two plastic round “Wiremold” surface mount ceiling fixture boxes from home depot, screwed together with a two bulb small used ceiling fixture mounted on the top and the relay mounted to a metal bracket at the bottom. The DROK fit perfectly in the breakout for the connector fitting with the two screwed together, bottom to bottom. I added a power switch and a quick connect for the bulb holder.

    Step 3 of the assembly is incorrect. Ground power goes to the input on the DROK, (Vin-) NOT its output. I went with a longer service cycle than recommended, finding perhaps 30-35% to be optimal for me, rather than 0%, for on-off best contrast and brightness.

    This is a handy and versatile strobe that works great at 40Hz.

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