Make a pair of Audiostrobe-compatible LED glasses for use with brainwave entrainment software

 by chantling
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Audiostrobe01.jpg
Audiostrobe glasses are used in conjunction with light and sound machines, as well as some brainwave entrainment software. The glasses have LEDs built in which pulse in synchronization with sound, usually either binaural beats or isochronic tones. The light and sound work together to entrain the brain's brainwaves. Essentially, your brain adjusts its dominant operating frequency to match the stimulus.

There are many claims made regarding brainwave entrainment; some have been scientifically proven, some haven't been proven, but make sense and are theoretically possible, and some sound like the deluded ramblings of a government conspiracy nut. Entrainment can relax or stimulate the brain; various frequencies have been shown to increase attention span, reduce stress, and aid in memory retention. In addition, entrainment can be used very effectively for hypnosis and meditation. There is some evidence that entrainment can, to a limited extent, replace sleep, although the only study I've seen used magnetic pulses to entrain the brain. Some people use it to achieve lucid dreaming, in which you realize that you're dreaming and take control. There is also, of course, a bunch of baloney floating around as well; people claiming everything from astral projection to telekinesis to regrowth of hair. Some even claim to have achieved enlarged genitalia through the use of brainwave entrainment. YMMV. If it works for you, email me and I'll let you know where to send the check.

This instructable will detail the construction of a modular pair of Audiostrobe-compatible LED glasses. I use a couple of entrainment programs, all of which can output an Audiostrobe signal. I've heard that photic entrainment, when combined with auditory entrainment, can be much more successful than the auditory stimulus alone. Upon pricing these glasses, I found that they range from $20-$60, and you had to buy a separate decoder device which starts around $115. Not only am I poor, but the thought of spending $60 on a pair of safety glasses with 12 LEDs glued onto them doesn't really appeal to me. So here's a set of plans for a modular Audiostrobe decoder. The decoder unit can switch between two outputs, so you can place two sets of LEDs on a pair of glasses and switch between them at will. You can either have two different colors of LED, different numbers of LEDs, or a different arrangement of LEDs on the glasses. The glasses themselves can be swapped out for a different pair, allowing you to keep several different styles for different needs or users. The decoder is built into an Altoids mint tin, because what Instructable would be complete without one of those?

The cost for the project will vary, depending upon what you have on hand and how good you are at scrounging. I already had everything except the audio jacks and the LM567, so I'm not sure exactly how much everything cost. The LM567 costs $1.80 at Digikey; I got mine 3/$1 at Electronics Goldmine. The jacks were $.53 apiece, and the 7805 costs $1.95 $.49 at Digikey. The electrolytic caps are fairly cheap; you only really need one of them if you're building this on the cheap. See step 1 for a list of what can be left out and what can't. The smaller ceramic caps and resistors are dirt cheap, but you either have to buy an assortment or buy a minimum amount (10 at Digikey). The switches I ripped out of a broken playstation controller (had an LED, too, though I didn't use it for this).
 
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Step 1: Some background info

After digging around on the Internet, I found a schematic detailing a circuit to decode Audiostrobe signals. I won't post it here because I was unable to contact MagicJim, the author, to get permission. I based my circuit upon that one; however, since he simply used the example circuit included in the LM567 datasheet, I'm fairly comfortable that I'm not infringing upon any copyright by posting this.

Audiostrobe works by encoding a high frequency (19200hz, apparently) signal into the audio stream. Most humans can't hear it, but a tone decoder can detect the signal and apply power to the LEDs when it is present. I'm not sure if the commercial decoders are this simple; maybe there's additional data sent with the stream, perhaps like a serial data line, only in audio. I was pleasantly surprised to find out that some software has brightness control built in, and it works with this circuit. After reading the tone decoder's datasheet, I'm clueless as to why. The decoder is a simple switch; if the tone is present, it connects the LEDs to ground, with no current or voltage regulation. The only thing I can think of is that the software uses PWM to drive the LEDs. In any case, this circuit works.

MagicJim commented that you need two circuits, one for each eye. Although dissimilar auditory stimuli work well, as in binaural beats and other techniques dealing with the two hemispheres of the brain, I've seen no studies showing any benefit to separate stimuli for the left and right eye. In any case, I was more interested in having selectable LED banks than in seeing how massive a migraine I could give myself by stimulating each eye separately, so both eyes are synced.

The decoder unit runs off of a 9V battery. Due to the inefficiency of linear voltage regulators, combined with the low capacity of 9V batteries, I don't expect battery life to be phenomenal. I originally planned to use the MintyBoost circuit to power it from two AA batteries. I didn't have the parts on hand, however, and I didn't feel like waiting for parts to arrive. I haven't been using the device long enough to get any real battery life data, and at any rate, I've been using old batteries that I had after replacing the ones in my smoke detectors, so it wouldn't be accurate anyway. If it turns out that battery life sucks, I may redesign the circuit to include the MintyBoost.

I've made a few changes to the original circuit. I added some ripple protection caps to the 7805. They're probably unnecessary since we're using a battery. I had planned on having a DC jack with contacts that broke when a plug was inserted. That way it'd run on batteries until you plugged in a source, at which point it'd automatically switch to the supply line. I scrapped that because there were too many cables going into the unit as it was. If you don't happen to have them on hand, you should be able to leave C6 and C7 out without any issues.

I also added a diode to protect against inserting the battery incorrectly. I placed a SPST switch for power, and a SPDT switch to choose between output lines. I also added a power indicator LED and accompanying resistor. If you don't want the indicator, LED1 and R3 may be safely left out.

The sound and signal input is supplied by a male to male audio cable. This cable can be hooked up to you computer's sound card if you're using entrainment software, your cd player if you're using commercial cds, or the output of a light and sound machine. I've used it with several different entrainment software packages, and it worked with all of them, but I haven't tried it with cds or l&s machines. I'd be willing to bet it works with cds, Hemisync for example, but I can't promise anything. L&S machines, on the other hand, are iffy. If they output a bog standard Audiostrobe signal, it should work fine. But if they utilize any special features, they may not work.

The cable for the glasses is a standard audio cable with a 3.5mm stereo plug. You can either cut one off of a pair of headphones or cut one end off of a male to male patch cable. I'd recommend the patch cable, as they tend to be a bit beefier, and can handle a bit more abuse.

There is a headphone jack included in the unit. Most entrainment software and cds require that you wear headphones, rather than speakers, while using them. I was originally going to just use an external cable splitter, but decided that the likelihood of me losing it and being unable to use the unit was great enough to justify the extra $.50 cost of an additional stereo jack.

Instead of using a 9V battery snap connector, I added some spring contacts. I've always hated snap connectors, and I've broken quite a few over the years. Unfortunately, I couldn't find any sacrificial electronics that were willing to give up their contacts, so I had to improvise. See step 4 for more info.

There are numerous design flaws in my unit. The actual glasses, for example, were built while I had MagicJim's circuit breadboarded, before I started making changes. I placed one set of LEDs on the glasses, wired them and expoxied everything into place, all the while thinking how great it would be if I could stick a second set of LEDs on the glasses. No, I thought, I don't want an extra wire dangling. It wasn't until roughly twelve seconds after the epoxy finished curing that it finally occurred to me that I could've used the second signal wire to power a second set of LEDs and use a SPDT switch to choose which one to use. That change made it into the circuit, but I haven't built a new pair of glasses yet.

There are several similar changes that could be made to make this unit better, but I'm going to detail the construction of the project as I made it. I know the unit I built works, but I can't guarantee any changes I suggest won't break it. In addition, by pointing out problems that occurred for me I might save somebody else some grief. At the end of the instructable, I'll suggest any changes I feel are necessary.

I'm not going to go into excruciating detail in certain areas that have already been covered well by other instructables. I'm not going to talk about etching the PCB, for example, because there are numerous instructables detailing exactly that. Nor am I going to go into extreme detail on things like drilling the holes for your jacks and whatnot. This is basically just the outline of what I did, what went wrong, and what I would change so that somebody else can do a better job their first time than I did.

I should point out that I am not an electrical engineer, nor do I know anything about electronics (a fact that will likely become painfully clear shortly). I don't know anything about audio, either, so I make no claims about the safety of your high-end sound card while using this. There's no amplifier in this circuit, and I've no idea how much of a drain it places on the signal. It's possible it can cause an impedance mismatch, and if so, your equipment might be toast. Additionally, there's no line isolation between the circuit and the signal input. You're placing an electrical circuit into a metal box and plugging it into your computer. If you were sloppy, you're going to have a bad day. You've been warned. If something bad happens, it's not my problem. Do not build this circuit if you can't take responsibility for what might happen. That dire warning aside, I've been using it for several weeks now, with two computers and a cd player, and haven't had any problems.

Oh, and for God's sake, if you've got epilepsy or some similar light-induced disorder, don't build a freaking machine designed to pulse light and then try to sue me, okay?
octalh says: Dec 21, 2011. 7:07 PM
Hi im using gnaural opensource software, i add a new isochronic tone voice but in the base freq i set to 19200 hz, i can see the beat in the spectro with adobe audition,this work with your audiostrobe?
dchall8 says: Jul 26, 2007. 12:43 PM
AaaaaaHA! Curse you evil brainwave entrainment glasses!! You are going to force me to post an Instructable for aluminum foil hats and reflective mylar glasses to reflect your evil LEDs and brainwave entrainments, things. Take THAT you pesky hypnosis-izers, aaaaaahahahahahahaha. I also have a 12-step Instructable ready for recycling an Altoids tin into a crush proof portable candy or cuff link holder. Otherwise, the technology in this is pretty cool, and you have paid very good attention to the small details.
Treknology in reply to dchall8Apr 28, 2010. 7:13 AM
Do you have filter-glasses for safely watching TV?
haunted_lady in reply to dchall8Apr 24, 2010. 5:35 PM
Weissensteinburg in reply to dchall8Jul 26, 2007. 5:00 PM
I think there is one for aluminum foil hats already,
LasVegas in reply to WeissensteinburgJul 26, 2007. 5:42 PM
Ah... But wide bandwidth hats? I wouldn't be satisfied with an aluminum foil hat that only filters out the AM band... ;)
T3h_Muffinator in reply to LasVegasJul 26, 2007. 5:55 PM
AGAGAGAGAGAG
Weissensteinburg in reply to LasVegasJul 26, 2007. 5:49 PM
Well then, I stand corrected.
silentdesperation says: Apr 25, 2010. 10:25 AM
I have wanted to get a mind machine for some time now, and would definitely like to give this project a try. Also now that NP3 is out I think it would greatly compliment it :D Thanks for the project instructions M8! :D
motoneta2 says: Nov 30, 2009. 2:55 PM
I´ve build the audiostrobe. I have one question: Do the glasses´ leds, while blinking, turns on and off? Because mine don´t...They just change the intensity of light. Is it right or something wrong?
If right, How could I make them turn on and off?

Oh...Thank you for sharing your project....


ronmaggi says: Sep 29, 2009. 10:07 PM
or you could put them on after you sat in your lazyboy...
pingpong_me says: Aug 30, 2009. 1:08 PM
Audiostrobe is not realy encoded... It's just an AM-signal at 19.2Khz. So you need a stereo AM-decoder to really enjoy the signal. Advantages are that the leds don't simply turn on/off but can varry in brightness.
tekproxy says: Jul 28, 2009. 7:15 AM
Well-made instructable!

I made one of these using the original schematics and it never quite worked right. This could be my fault. I always had to re-tune P1 to get the lights to flash. It was wonky. Then I found this discussion on how the circuit is actually wrong: http://health.groups.yahoo.com/group/bwgen/message/4401
fighto says: Jul 25, 2009. 1:26 PM
Should the capacitors be a certain voltage?
drewb0y says: Oct 25, 2007. 2:49 AM
I have built this circuit using your instructions plus a few embellishments. I added the switched power input jack, the potentiometers from the original schematics, and a second channel for left/right, also on the glasses i used 2 lead bipolar red/green leds and added a set of dpdt switches to switch eithr left/right to red or green. So far I have only tried it with BWGen and your test file and it seems to work. However when you run the setup on BWGen and it goes through the audiostrobe device testing, nothing happens. When using BWGen or the test file, the lights do blink when the potentiometers are adjusted properly. Have not tried Gnaural or any premade mp3s yet. Do you have any idea what the BWGen testing is looking for in order to pass the testing thst is missing? Thanks and great project.
Israel Ribas in reply to drewb0yApr 15, 2009. 2:05 PM
Hi drewb0y, Man, can i ask to you? Can you post (or email me) you project? ´couse I believe that the realy project (magikJim) it´s true about blink left/right separetly (sorry about my english, I´m from Brazil). This is the realy effect about brain waves. Thanks
chantling (author) in reply to drewb0yOct 25, 2007. 10:15 PM
Hmm, not sure what's happening here if the glasses blink properly otherwise. You're saying that when you click the button to test the glasses, they don't blink, but when you play a preset with BWGen, they do? That's very odd. BWGen gets no feedback from the glasses; this is just a passive test that you can use to make sure your glasses blink properly, so they don't "pass" or "fail". On the "Check Audiostrobe Output" screen, I check the "I have an Audiostrobe device attached to my sound system" box and hit the "Test Audiostrobe" button. This causes my glasses to flash at approx. 4Hz. Going to the next screen, you have the option to adjust the brightness level and waveform of the signal. It's probably already set at 100%, but if it's not, that may be where your problem lies. My unit gets dimmer as you go down until about 30%, where it just suddenly cuts off. If that's not the problem, try adjusting the output volume on your computer while it's testing. My glasses are pretty sensitive, but it's worth a try. The last screen allows you to set the zero brightness level. This apparently lets BWGen use the weakest (quietest) Audiostrobe signal level that reliably fires your glasses. I suppose some people might be able to hear the frequency used to trigger them, though it's supposed to be beyond the range of normal human hearing, and having it as low as possible would make it less intrusive. I don't usually change it from 50%, as I can't hear the carrier so it doesn't bother me, but my glasses will go as low as 30% before they start flashing. As long as they work when you're actually playing an Audiostrobe track, I wouldn't worry about it. Play with the settings on the second and third page, and see if that changes anything. I'm sorry I can't be more help, but I can't think of a reason that they would work in one situation and not the other. At least they work when you're playing a track and not when you're testing; it would suck if it was vice versa.
Israel Ribas in reply to chantlingApr 15, 2009. 2:17 PM
Hi chantling, About your vision about brain wave, the realy is that the balance of hemispheres of the brain is correctly (see in the net about EMDR). This affect the fisiology of the brain. Then, if you review the Audiostroble 1.02 project and rebuild to us some newer version I say: thanks! (sorry about my english). Look, I built your project but, the one that happens is that he blinks independently of being linked with sound and in the same speed. What did happen wrong in your opinion? Could you tell me something? Please, help me to solve this problem, I have there is a long time sought on these audiostrobe. Thanks.
mcfarlandmcfly says: Nov 12, 2008. 5:15 PM
I analyzed the spectral waveform of the brain wave output. It looks like the audio strobe signal ranges from 17.5kHz to 22.5kHz. And I checked that every time a pulse occurs on the audio strobe signal it corresponds to a light flash. Ex: the light is suppose to pulse at about 7Hz for the awakened mind part in the very beginning. The pulses exactly match a 7Hz signal. This means that all we need is a high pass filter set to pass all signals above 15kHz. Then we can just use that signal and send it to a comparator with a reference set a whatever threshold you want the light pulse at. This whole business with the tone decoding seems unnecessary to me. Anyways post back or email me if anyone has done this yet. Otherwise I will make this my Christmas break project. -Matt
JetCityOrange says: Aug 8, 2008. 7:17 PM
Yes, brainwave entrainment works. You don't need fancy software. I offer free binaural beat MP3 files on JetCityOrange.com

Different tones for specific brainwaves (alpha, beta, and theta). Download them and see for yourself. They're perfect for iPods or MP3 players. Headphones are a must for binaural beats to work.

enjoy!
dierke says: Feb 18, 2008. 3:28 PM
If Someone has all of the supplies to make it, I would be happy to purchase them from you. Just let me know.
dierke says: Feb 14, 2008. 5:31 PM
I'm new to this. What voltage are the Capacitors? And if I use red LED's, would i have to change the Resistor? I also cannot find 0.005uf Capacitors anywhere? does anyone know a website that i can buy all of this stuff at?
MAXxyz says: Jan 5, 2008. 3:00 PM
I have built this circuit twice now, and all that it does is to sound control the leds ... can anyone tell me what is wrong? its impossibe to find out anything about the IC... I checked it throgh again and again, and i really can't see what is wrong...
biggmatt2000 says: Dec 4, 2007. 10:54 AM
What was the intensity of the LEDs?
chantling (author) in reply to biggmatt2000Dec 13, 2007. 12:56 PM
Not sure. I used some that I had lying around the workbench. They're high intensity, but I don't know the specs.
Biotele says: Jul 27, 2007. 2:18 PM
You can use my rechargeable power supply and do away with the voltage regulator. The voltage regulator acts like resistor producing heat to drop the voltage.

http://www.instructables.com/id/EWGTDSKF2ZML6UK/

In place or center tapping the battery to get + and -, you need only to rip out three cells and replace them with LEDs.
chantling (author) in reply to BioteleJul 28, 2007. 10:42 PM
That's a good idea; I might consider it if battery life turns out to be an issue. I'd have to buy both a rechargeable 9v and a charger for it, though; my chargers only charge AA and AAA. Two questions, though; you made the comment that the LED blocks the normal flow of current. So I'd have to use the wires to connect the battery to my circuit? Also, the LEDs light while the battery is being used as well as when it is charging, correct? That's ~60ma of current going just to run the LEDs; that's more than 25% of the battery's output wasted. Am I off base here? So far, battery life's not as bad as I thought it would be; I have a battery that I thought was fairly drained, and I've used it for around 3.5-4.5 hours, I think. Still going strong. Haven't been doing a very good job keeping track of usage because the battery wasn't fresh to start with.
Biotele in reply to chantlingJul 29, 2007. 3:25 AM
You need solder a wire before the LEDS that will go to the project. The LEDs only light up when charging. They just drop the voltage level to the proper voltage to charge the rest of the cells.
chantling (author) says: Jul 28, 2007. 10:44 PM
Made a couple of changes. Had the wrong price for the 7805 from Digikey; added links to Electronic Goldmine for IC1 and IC2; discovered to my horror that the freeware tools don't have Audiostrobe support; and I was mistaken about NP3 being just around the corner.
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