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Updated
12.06.06
<= Ultimate 2b Construction
Notes for the Ultimate 2b
The RS Ultimate 2b
Theremin - A Gift from Lev Sergeyevich Termen
Design by Christopher - www.oldtemecula.com
Note: Deviating from my
exact instructions, will most likely
doom your project!
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"The
theremin is basic electronics. . . yet very difficult,
baffling even to my engineer builders"
My
circuit board with "Component Patterns" makes
construction straight forward.
Use sockets for the IC's, sometimes I remove the
TLC555 for a different sound.
Component
Polarization - Several
parts must mount in their correct direction!
Integrated Circuits:
U2
& U4
Both IC's have a notch on one side of their
package. With this notch to the left there should be a
dimple just above Pin #1 in the lower left side. This pin must solder at the location
Pin #1 is indicated.
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Transistors:
Q1 & Q2
The transistors have a half
moon shape. Both transistors mount in the same direction
with the Q2 flat side facing away from the board. Q1
flat side faces towards the IC's.
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Diodes:
D1, D2 & D4
Diodes usually have a
black line on one side of it's body. This is the
negative side. The line also represents the line
opposite the arrow when viewing a schematic.
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LED 1 & LED 2
The fat lead inside the clear plastic LED is the
positive side or anode. Solder this to the + plus side
indicated on the pc board. This works for the Radio
Shack LED but is not always the case. Read
the package your part came in for proper polarity and
direction.
These LED's
have a 12 degree projection angle and
throw a 3000 mcd beam out 3 feet (1
meter)
Other LED Colors have
higher operating voltages and don't work as effective in
the Ultimate 2b. |
Electrolytic Capacitors:
C10,
C12 & C15
These types of capacitors will have
+
or
-
symbol printed on it's
packaging. If a
-
negative
symbol is only shown
this solders opposite the
+
plus
indicated on my board. A plus side marking solders to the
plus side indicated on the board.
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| You can get lucky
and hear the theremin whistle immediately and not require major
tuning. Measure the C2
& C8 - 100 pf capacitors and use the two that closely
match each other in value. |
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Look over the Frequently Ask Questions
FAQ
before you begin this Project!
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Below are important building tips!
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The main area people have problems in building the RS Theremin
Ultimate 2b is their "soldering" or a poorly etched circuit board.
Don't etch until the Toner (ink) iron on/transfer looks good,
otherwise scrub it off and try again from what you learned.
The Ult-2b must not be built on an experimenter's plug-in proto board.
The RF oscillator section won't behave properly so your wasting your
time.
Another problem is when builders use some other version of coils not
realizing the importance and how critical yet simple my coil design
is. Equally important is the coil angle and distance to one another.
Any two of the same type general-purpose NPN transistors will work if
their pin out is the correct EBC (emitter - base - collector).
If you are able to measure the hfe of the transistors, use two that
are similar and less than a 200 in value. Ultimate-2b temperature
drift is not an issue but matching the transistors may add more
stability to the fine balance between the oscillators. Measuring also
eliminates transistor duds and verifies the EBC pin out..
If you are able to measure a capacitor's value, use two 100pf that
have the most identical values. This accuracy is needed to balance C2
& C8. (Two at 95 pf is excellent)
In my Ult-2b design the pitch will be affected slightly when built
into a small enclosures. Notice in my design photos that I always
mount the Ult-2b pc-board underneath rather than enclosing it. This
reduces deep voice, lower frequency wave shape distortion. Reflection
of the magnetic field between the coils occurs in closed wooden box.
I am curious how many people finish. Did you discover something that
was unexpected or unusual? Please tell me about it after you reach
your own construction conclusion. The theremin is an evolving magical
instrument with new ideas waiting to be discovered.
There are several things I search for in my theremin investigation,
affordability, unique voice character that's alive & musical with
linear & ideal note spacing. |
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1. RS
Components
List
You will want to
print this page.
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5.
Tuning the Oscillators
Most exciting
moment!
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2.
Etching your own PC
Board
PDF request info at bottom of the Ultimate 2b
home page.
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6. Volume Control
Using the Hand Held Solar Cell
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3.
Assemble your board
You are currently on this page.
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U2b
Schematic
Plus what
changes were made to version "b"
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4. Making
& Mounting the Coils
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Wave Shapes
What they sound like 04.29.05
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The
Lev
Antenna changes the
emitted RF wave polarization 90 degrees,
to a
right angle from the original. It also allows for a more controlled distribution
of the radiated magnetic field.
Contrary to what most people believe, theremin
control is created from your hands influence on the amount
of radiated
energy escaping the theremin antenna.
Interesting fact: The Lev
Antenna design can make the higher octaves two
inches from the antenna wider than the lower octaves in the outside playing
field? Not desired yet Strange &
Remarkable!
To be called a "true
theremin voice " it must be generated from
the heterodyning principle.
The oscillator frequencies must match one another
"perfectly". This would be the Null Point where no
sound is heard. Pulled slightly off Null is the difference that creates the tone.
400 cycles difference from Null or the other oscillators
frequency is what creates the 400 hz tone.
When the oscillators are far from matching in frequency
due to not being tuned, you hear nothing. When you have
your theremin tuned to a very high pitch, the theremin
control will seem to lack response unless your close to the
antenna.
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