From: jgoldswo@coyote.csusm.edu (John Goldsworthy)
Newsgroups: alt.dreams.lucid
Subject: Circuit Plan
Date: 12 Jul 1994 07:16:44 -0700
Lines: 141
Well here goes. I here goes. I hope this plan makes it to the
newsgroup. As you can see vi and I don't get along yet. :) mkesk
Home Brew REM Circuit
OK, here is the circuit that I promised to make up for posting
on the Lucid Dream News Group. I can't claim that the results
you will get will be the same as mine since there are variables
that hve to be worked out by the person constructing the device.
Namely the positioning of the LED emitter and receiver in the
plastic eyepiece nd the triggering levels set up for the comprator.
That said here is the circuit.
Diagram 1.) Eyepiece
A. C. B. A. Infrared LED
___\_|_/___ B. Infrared sensitive phototransistor
3 3 C. Mini LED (I used green)
___/ \___ All components available from
Radio Shack.
The eyepiece consists of one half of a pair of swim goggles
purchased for approximtely $1.89 at a local dept store sports
section. I chose a goggle that utilized a flat viewing surface
for the user since this facilitated an easy to determine what
angle the emitter and receiver oppose each other. Upon reexamining
my eyepiece that the angle I used was approximately 30 degrees.
This is not to say that this is the optimum angle for this type
of use, it is only what I found that worked well for me. I
drilled the holes using a common electric hand drill, taking care
to first drill a pilot hole using small diameter bit so as to
establish pathway for the larger bit that allowed the LED and
phototransistor. The size of my pilot bit was a #36 and the finishing
bit was a #21. The #21 produced a hole that was very close to the
desired diameter of the LED and with a little help from a rattail file
I was able to produce a good snug fit. A tight fit is important as
you don't want the emitter and receiver shifting in their positions
respective to one another since this would alter the signal produced
by the REM eye movement.
Diagram 2.) Circuit
Legend: (-) = circuit ground (+) = 9 volts (from battery)
PT = phototransistor IR = Infrared LED
741 Op-Amp (Pins are OPI = Opto-isolator
A. B.
(-)--/\/\/\/\--(+) (-)--/\/\/\/\--(+)
/\ /\
3 Z------------------Y
0 3 __________
PT 3 \3 * 3\--(+)
0 @---\3- 741 3\ Z---\Z------?\-----> (1.)
C. C--------\3+ Op-Amp 3\-----Y 3 OPI 3
Z/\/\/\/\-Y Z\3 3\ Z--\3 3\-----> (2.)
C---Y 3 @----------Y 3 @------Y
3 (-) (-)
(-)
This 7805 is used to power the
Z--------? infrared emitter in the eyepiece.
3 LM7805 3 The resistor is used to limit
3 3 current nd protect the emitter.
@--------Y
] ] ] 1200 ohms
(-) (+) ---/\/\/\/\/--0 IR 0---->(-)
This is the heart of the circuit. The 741 Op-amp is being used as a
comparator. For those of you who don't know about electronics a
comparator does the job of comparing an incoming signal voltage against
a refernce voltage. When the input signal exceeds the referance voltage
the output of the op-amp swings high to the supply voltage. In the above
circuit, the incoming signal is the voltage being taken from the voltage
divider made up of PT and C. It is fed into the non-inverting input of
the op-amp and compared aginst the refernce being fed into the inverting
input. The inputs are located by counting the pins on the op-amp starting
at the asterisk and proceding CCW. Number 2 pin is the inverting input
and number 3 pin is non-inverting. The bridge containing PT is the portion
of the circuit requiring the most tweaking to get the desired response to
show up at the computer's game port. I placed a voltage divider in the
form of a potentiometer (A.) so I could regulate the voltage that was
available to the top of the input bridge circuit. I also placed a
potentiometer in the lower half of the PT voltage divider so I could balance
and tune the resistance of this half of the divider withth the resistance
the PT presented to it when I was wearing the eyepiece. The value for (A.)
is not crucial as it only supplies voltage and any pot. can do this. The
value of (C.) that I found worked best for me was 100K (kilo ohms). The
output of the op-amp found at pin number 6. I fed this into an opto-isolator
simply to protect the game port from the circuit itself. This really is not
necessary as the unit is only powered by a 9 volt transistor battery. You
could easily substitute a transistor working as a switch or a small 5 volt
relay. Numbers (1.) and (2.) are the output and return from the game port of
the computer. At your game port there are pins looking like this,
_________________
\ * * * * * * * /
\-------------/
Counting from the left, number one pin is 5 volts, this goes to either
(1.) or (2.) of the output side of the opto-isolator, transistor, relay,
or whatever you use to pulse this voltage. Pin number three of the game
port diagram is the return for the 5 volts. As the comparator snaps out
a response to your REM eye movement the 5 volts coming from and returning
to the computer varys accordingly.
SOFTWARE
The program that I wrote to monitor the number of REM's during the night
was written in Quick Basic. I'm not posting it here as it is fairly long
and this post is getting pretty big as it is. The program, in short, starts
by doing a loop which watches the system clock until a preset time is
reached. As soon as this time is reached it begins watching the game port.
It will count the pulses at the game port for a specified time period.
If the number of pulses is over a certain amount, it increments a variable
and resets the counter to begin fresh count. If the variable reaches or
exceeds a certain number within its own specified time frame the computer
outputs a 5 volt pulse from the printer port to the green LED in the
eyepiece. The program then waits so as not to keep prompting you with the
LED and perhaps awaken you out of the dream it just informed you about.
After this waiting period the program resets all counters and begins fresh
counting. If the above mentioned variable does not reach or exceed the
specified number in order to qualify for a LED prompt to the sleeper, the
program simply resets in the same way as above and begins watching again
as this would signify that dreaming was not in progress and probably only
random eye movement or system glitches were responsible for any count.
That's it for me right now. :) I am typed out. If you have any questions
email me and we can sort out details. Hope this helps any of you wanting
to build a cheaper version of a lucid dream prompter. I am only guessing,
but the cost for parts alone would probably only run around $20 to $30.
This is sans the computer of course. :)
So Long For Now
John
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