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______________________________________________________________________________
| File Name : LDHELP.ASC | Online Date : 12/19/95 |
| Contributed by : Jerry Decker | Dir Category : BIOLOGY |
| From : KeelyNet BBS | DataLine : (214) 324-3501 |
| KeelyNet * PO BOX 870716 * Mesquite, Texas * USA * 75187 |
| A FREE Alternative Sciences BBS sponsored by Vanguard Sciences |
| InterNet email keelynet@ix.netcom.com (Jerry Decker) |
| Files also available at Bill Beaty's http://www.eskimo.com/~billb |
|----------------------------------------------------------------------------|
The following file was written to accompany the Lucid Dream project. There
are three files associated with the Lucid Dream project;
LDHELP.ASC - electronics tutorial
LDMON122.ASC - details and circuit to build the Lucid Dreamer
LDMON.BAS - QBASIC program to operate your device
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REM Sleep Monitoring and Signaling Circuit and Program
created by
John Goldsworthy - jgoldswo@coyote.csusm.edu
developed by
Boyd Johnson - johnson@spectra.com
Version Beta 1.22
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Mini Electronics Tutorial
This is a little primer to get people without an electronics background up to
speed to be able to build this circuit and know how it works. It will also
help you troubleshoot it if it doesn't work. I cut pieces out of a mail
message I had sent to someone trying to build it, so it may not be laid out
well at this point. Any corrections, additions, or best of all, pointers to a
good brief, on-line electronics tutorial would be appreciated.
Send to (johnson@spectra.com).
------------------------------------------------------------------------------
I'll start out with the basic concepts of electronics.
Resistance, as the name says, is something that _resists_ the flow of
electricity. It is not related to either flow or force. An analogy they
sometimes start with in electronics classes is drinking a very thick chocolate
malt. If you use a normal straw it is kind of hard to suck out the malt.
If you have a 1/2 inch wide straw it would be much easier, and if you had one
of those plastic coffee stir sticks with the tiny holes through it it would be
almost impossible to drink it. The difference is the resistance of the
straws.
Voltage is the force behind the electricity. It is highest at the power
source (battery, power supply, wall outlet) and gets lower as it goes through
the circuit back to the return. Using the malt analogy, voltage is the
"pressure (or vaccuum in this case)" you use when you suck on the straw. The
harder you suck on the straw, the more malt you get.
Current is the volume of flow of electricity. It is the malt in our analogy.
These three are totally separate concepts but they are the only three
variables in probably the most important formula in electronics, Ohm's law.
Voltage ("E", which stands for "electromotive force") equals current ("I", I
don't know what 'I' stands for) times resistance ("R"). That is, E=I*R.
Example 120 = 2 * 60.
If you have 120 "volts" of electricity going through a 60 "ohm" resistor you
will _always_ have 2 "amps" of current flow (providing the resistor doesn't
burn out :)).
Voltage and resistance are the two factors that are easiest to control. The
variables can be switched around using laws of math (dividing both sides of an
equation by the same thing) so that all three of the following formulas are
the same. E=I*R, R=E/I, I=E/R.
Using our analogy, if you cut the resistance in half by using two straws side-
by-side instead of one straw and suck the same amount (voltage) you will get
twice as much malt (current). If you double the resistance by putting the two
straws end-to-end you will get half as much malt. That is all there is to
parallel and series resistor circuits.
If you put resistors in parallel the same amount flows through each resistor,
but more current is flowing after they connect again into the circuit. If you
put two resistors end-to-end the same voltage is spread between the two
resistors, so with half the voltage only half the current will flow through
the resistors. That is the purpose of the resistors in my circuit. They
"divide" the voltage across several (2 or 3) "components" so by the time it
gets to the LED there is only 2 volts left.
One more related concept is "power". Power is the product of voltage and
current, so P=I*E. I won't go any further, but you can substitute the
equivalents of I and E from Ohm's law in there also if you don't know what one
of the variables is.
END OF TUTORIAL
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Some troubleshooting information for the Lucid Dreamer REM sensing circuit.
I used silicon diodes, but germanium diodes should work almost the same. The
only difference is silicon diodes "drop" .7 volts in saturation while
germanium diodes drop .3 volts. That just means the 5V you start with will be
4.7v instead of 4.3 volts after it passes through the diodes. You need to get
it down to about 2 volts by the time it gets to the LED, depending on how the
LED is rated on the package it came in.
You need to make sure that in any electronic circuit diodes are not backwards.
This includes all silicon based components such as diodes, zeners, LEDs,
phototransistors or transistors. One thing you should notice is with no power
to the circuit (NEVER MEASURE _RESISTANCE_ WHILE THERE IS POWER TO THE
CIRCUIT) the "resistance" across a diode will read drastically different
depending on which direction the diode is pointing, or rather what side of the
diode the red and black meter leads are. That is because the purpose of a
diode is to let electricity through in only one direction. That is why I
chose them. I don't want the voltage from one parallel port pin to loop back
to another parallel port pin.
If the circuit does not have power applied to it the DCV setting will not
display anything of value. Only something like a photocell will display
anything of value, because it is a source of power. The DCV range measures
voltage only, and if there is no voltage applied to the circuit nothing of
value can be read. I say nothing "of value" because even if you hold the
meter leads in your hands and have it on a very sensitive range you'll
possibly see something just from the minute electrical fields in your body.
On resistance also your skin will make a difference, so it's best not to hold
both leads with your fingers while measuring resistance of something.
The best way to test the circuit would probably be with the voltmeter. I'll
draw up a little chart showing _approximations_ of what you should expect and
what other readings could be caused by. I haven't measured them to see just
what they should be. Use the "Calibration" menu option of the ldmon program
and create test flashes by using sub-option B or C.
You need to use the voltmeter to find out if they are backwards. The meter
won't tell you until you get experience with _your_ meter seeing which meter
lead is positive and which is negative. It may or may not be the red for
positive. It probably is, but I never really checked many different meters
for comparison.
With power applied to the circuit, connect the black meter lead to the
negative power lead. In my circuit it is pin 5 (-) of the game port. Leave
it there for all voltage measurements _unless_ you are specifically measuring
the voltage _across_ a certain component. Now put the red lead on the
parallel port pin 2 side of the diode or resistor on that line.
MAKE SURE THE METER IS ON VOLTAGE AND NOT CURRENT OR RESISTANCE.
Failing to do so could burn up your meter. You will probably not ever need to
use the current measurement position on your meter if it has it. You have to
really know what you are doing before using it anyway, otherwise you burn out
your meter. Make the circuit activate from the Configuration menu, selecting
the (B) or (C) options, then pressing 0<ENTER> to flash it. Look at the
meter. It should be going between 0V and 5V. If so, your parallel port is
working right. Move on to the next step.
Move the red meter lead to the other side of the diode (assuming it is a diode
and not a resistor. I probably better make that one way or the other in the
diagram for troubleshooting help). Make it flash again. If the voltage
barely changes from 0V at all your diode is backwards. If it goes to 4.3 or
4.7V (germanium or silicon) it is correct. If it is _always_ nearly 5V your
LED is backwards.
Now move the red meter lead to the other side of the resistor just before the
circuit gets to the LED. The point on the wire makes no difference. A wire
is supposed to be just like a point in electricity and has very little
resistance. Make it flash again. The voltage _should_ go between 0V and 2V
now. If it is below 2V your resistor may be too big. If it is higher your
resistor may be too small (ohms, not size). However, the LED may mask
anything that's not a drastic difference, because it isn't a simple resistor
providing a constant resistance. It _tries_ to keep the voltage across it to
2V.
Here is the circuit from highest voltage on left to lowest on right. Since
all points along connected wires are electrically the same as if they were at
the same point I will change the diagram wiring to simplify it for test point
locations. The components are still laid out the same despite the difference
in appearance.
Red meter lead voltage test points (A) to (K) , joystick pins JS-1, JS-3, JS-
5, and parallel port pins PP-2 and PP-3 out of 8 pins. Keep the black meter
lead on test point (C).
5V ground
JS-1--(+) (-)
| |
circuit |(A) 500 (B) (C)|
1. ---> +-----------/\/\/\-----------IR----------------+
| |
|(A) 3.1K (D) (E) |
2. ---> +-----------/\/\/\-----------PT-------JS-3 |
|
(F) diode (G) 2.2K (H) (C)|
3. ---> PP-2--------->|----------/\/\/\--------+--LED---+
|
(I) diode (J) 2.2K (H) |
4. ---> PP-3--------->|----------/\/\/\--------+
Four circuits above have voltage tables listed below:
1. IR LED circuit
(A) (B) (C) Comment
___ ___ ___ ________________________________
5 2 0 Normal voltages
5 5 0 IR is backwards or burned out
5 1 0 Resistor is too high value or bad
2. PhotoTransistor circuit
(A) (D) (E) Comment
___ ___ ___ ________________________________
5 4 1 Normal voltage with no light
5 2 1 Normal voltage with bright light
5 5 ? LED is backwards or burned out
5 3 3 Resistor is too high value or bad
{I'm not sure about what should be at (E)}
3. First flash circuit line PP-2
(F) (G) (H) (C) Comment
___ ___ ___ ___ ________________________________
0 0 0 0 Flash is not enabled
4 3.5 2 0 Flash is active (INTENSITY 1-8)
4 1 1 0 Diode is backwards
4 3.5 1 0 Resistor is too high value or bad
4 3.5 3.5 0 LED is backwards or burned out
4. Next flash circuit line
(I) (J) (H) (C) Comment
___ ___ ___ ___ ________________________________
0 0 0 0 Flash disabled or INTENSITY 1
4 3.5 2 0 Flash is active (INTENSITY 1-8)
4 3.5 2 0 Flash is active (INTENSITY 2-8)
4 1 1 0 Diode is backwards
4 3.5 1 0 Resistor is too high value or bad
4 3.5 3.5 0 LED is backwards or burned out
If you use the camcorder IR LED viewing technique described in the
description, it's best in total darkness, and if you have a black-and-white
camcorder eyepiece it will be dull gray. It gets brighter gray when it is
pointed directly at the camera lens. Hold it as close to the lens as the
camera will focus. You may need to turn off auto-focus so it doesn't keep
trying to refocus in the dark.
> Maybe the IR and PT need more power than they're getting. The package says
> they can have a maximum of 20V. (On a different part it says it can only
> take a reverse voltage of 2 though).
I'm not an expert, but I believe that means it will take 20 volts when it is
backwards, not putting off any light (or in the case of the PT not changing
resistance). If it is forwards in the active state it is only supposed to be
2V.
> Since I have no real knowledge of electronics, I'm not sure how everything
> works, but in your diagram where the PT is connected up to pin one (+)
> then goes to connect with pin 3, what is pin 3 used for? Doesn't the PT
> need a negative voltage as well? (that's probably what pin 3 is right?)
Pin 3 is the joystick sensing line. There is internal circuitry on the I/O
board to return it to (-). On a normal joystick moving the stick changes the
value of resistance between 5V and the sense line on pin 3. That is exactly
what you are doing with the resistor and PT.
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