Quick and Dirty Photic-Stimulation Goggles ==========================================

Return to Biofeedback Index

WARNING: The use of these goggles may induce seizures in epileptics or people prone to epilepsy. Get your doctor's permission before using this device. I assume no liability or responsibility should you choose to do something as stupid as use these without a doctor's permission.


Although I've built these goggles myself, the following plans are untested; though it's such a simple circuit that you shouldn't run into any problems.


Updates of this file and other mind machine related files may be obtained via WWW: www.elf.com/pub/u/x/home.html

Parts required: * (2) clear super-bright LEDs * (1) LM3909 Led Flasher IC * (1) 47 microfarad electrolytic capacitor [C1] * (1) 9 volt battery * (1) 9 volt battery holder * (1) pair cheap swimming goggles or safety goggles * (1) switch [S1] * (1) small circuit board * (1) case - a plastic band-aid box will work fine * (+) speaker wire (for steps 7 & 8) * (+) duct/electrical tape Tools required: o___o____GOGGLES * solder iron | | | | |(+)battery * solder wire | | | | | * hand drill | | |8 |6 |5 | | ========== (-)| S1 [ LM3909 ] o = connecting wires C1 |____1========== (+)| |2 |4 | | | |_________| |(-)battery

NOTE: Read the entire article before attempting construction.

1. Put LM3909 IC on circuit board. 2. Solder pin (4) to the negative wire of battery holder. 3. Solder pin (5) to the positive wire of battery holder. 4. Solder pin (1) to one side of S1. 5. Solder other side of S1 to negative side of C1. 6. Solder pin (2) to positive side of C1. 7. Solder pin (6) to one side of a length of speaker wire. 8. Solder pin (8) to the other side of a length of speaker wire. The speaker wire will be attached to the goggles in the goggle construction section.

Constructing the Goggles ======================== 1. Drill one hole in the center of each eye of the goggles. To avoid having to use super glue to secure the LEDs, start with a smaller drill than you think you'll need. Then drill progressively larger holes until you can just barely push the LEDs through the holes.

2. An LED has two wires coming out of it - a short one and a long one. One is negative and one is positive. I don't recall which is which, so you'll have to figure this out for yourself. If the LEDs aren't connected properly, they won't light-up. Touch the wires coming from pins (6) and (8) of the LM3909 IC to one LED. If it doesn't light-up, reverse the position of the LED or the wires so that it does light-up. Then, keeping the wire coming from pin (6) connected to one side of the LED, attach the wire coming from pin (8) to the second LED and touch the remaining wires (one from each LED) together. If both LEDs don't light, reverse the position of the second LED.

3. Put the LEDs into the goggles in the sequence in which you got them to light in step #2. Solder a wire between the two inner-most wires of the LEDs (one from each LED, in the center of the goggles).

4. Solder the two remaining LED wires to the speaker wire.

Operation ========= Connect the battery to the battery holder, put on the goggles and close your eyes. Use the switch to select between the two flash rates. When the switch is open, the LEDs will flash at approximately 2 Hz (2 flashes per second). When the switch is closed, the LEDs will flash at approximately 5.5 Hz (5.5 flashes per second). To increase the speed of the flash rate, substitute a higher value electrolytic capacitor for C1.

Be forewarned that the flash rates given here are only approximate, as individual capacitors of the same value can vary slightly. Thus, if you're looking to recreate some namby-pamby breath of the earth frequency with an accuracy of two decimal points, you'll need to look elsewhere. The 555 Timer IC can give you more accuracy, but the circuit is considerably more difficult to build. Even the 555 may not deliver the precision you require. In this case, use crystals (and I don't mean the kind Shirley Mclean uses).

If you know of an easy way to alter this circuit such that one can throw in an extra switch and have the LEDs flash _alternately_, please e-mail me at "x@apocalypse.org".

Batteries =========

When I built my own goggles, I used a 4 AA battery holder rather than a 9 volt holder. I suggest using a 9 volt battery for the sake of keeping things more compact. However, 9 volts may be too much voltage for two super-bright LEDs to handle - and it's certainly too much for one LED to handle (if you run the wires of one LED over a 9 volt battery, it will surely burn itself out after about 5 seconds), so do what you wish. A 9 volt battery should be sufficient to handle 4 LEDs if you'd like to increase the brightness of your goggles.

(C) 1995 Xochi Zen - You may distribute this file freely as long as you do not alter its contents (including this notice) or charge money for it.

--------------------------------- EOF --------------------------------------

Return to Biofeedback Index