aion LUNA User manual

LUNA OPTICAL TREMOLO 1
PROJECT NAME
LUNA
BASED ON
EFFECT TYPE
PROJECT SUMMARY
DOCUMENT VERSION
4ms Tremulus Lune
An all-analog tremolo featuring six knobs for fine control over every aspect of the waveform.
Tremolo 1.0.2 (2020-12-07)
BUILD DIFFICULTY
Intermediate
This documentation is for the PCB-only version of the project. The full kit documentation is similar,
but more specific in certain areas due to the customized hardware that is used.
IMPORTANT NOTE
Actual size is 2.3” x 1.86” (main board) and 2.3” x 0.86” (bypass board).

LUNA OPTICAL TREMOLO 2
TABLE OF CONTENTS
1Project Overview 7Drill Template
2Introduction & Usage 8Enclosure Layout
3-4 Parts List 9Wiring Diagram
5Build Notes 10 Licensing
6Schematic 10 Document Revisions
INTRODUCTION
The Luna Optical Tremolo is a modified version of the 4ms Tremulus Lune, a classic DIY optical tremolo
circuit that allows fine-grained control over the LFO shape.
Several of the Tremulus Lune circuit’s optional modifications are included standard in this PCB,
including the Symmetry control as well as an external gain adjustment control so you can achieve unity
volume with any setting.
The Luna adds a few improvements to the original design, including an input buffer to reduce noise and
some added filtering to counteract ticking from the LFO. All of the knobs are located on the front panel
in an efficient layout that is easy to build.
The new version of the Luna now uses standard 16mm potentiometers, which should make it easier to
source parts than the last version. It also now has the Rate LED integrated into the footswitch board.
USAGE
The Luna has the following controls:
• Rate is the speed at which the tremolo modulates.
• Depth sets the volume of the tremolo at the lowest peak of the waveform. You can turn it all the
way up for a choppy sound, all the way down for a clean boost with no modulation, or anything in
between.
• Symmetry allows you to adjust the position of the peak of the LFO in the cycle. On one end, there
will be a fast rise and a slow fall, like the attack of a piano. On the other end there will be a slow rise
and a fast decay, like a swell effect. The middle position is a normal tremolo sound with equal rise
and fall times.
• Smooth lets you set the shape of the LFO. On one end of the knob’s range, it’s a triangle wave. In the
middle, it’s a sine wave, and on the far end it’s a square wave.
• Spacing allows you to space out the LFO cycles. The width of the LFO pulse is the same, but there is
a delay between cycles—creating a unique effect that is very uncommon in tremolo designs.
• Volume sets the volume of the tremolo at the highest peak of the waveform.

LUNA OPTICAL TREMOLO 3
PARTS LIST
This parts list is also available in a spreadsheet format which can be imported directly into Mouser for
easy parts ordering. Mouser doesn’t carry all the parts (most notably potentiometers) so the second tab
lists all the non-Mouser parts as well as sources for each.
View parts list spreadsheet →
PART VALUE TYPE NOTES
R1 1k Metal film resistor, 1/4W
R2 1M Metal film resistor, 1/4W
R3 1k Metal film resistor, 1/4W
R4 47k Metal film resistor, 1/4W
R5 47k Metal film resistor, 1/4W
R6 1k Metal film resistor, 1/4W
R7 1M Metal film resistor, 1/4W
R8 220k Metal film resistor, 1/4W
R9 150k Metal film resistor, 1/4W
R10 220k Metal film resistor, 1/4W
R11 220k Metal film resistor, 1/4W
R12 2k7 Metal film resistor, 1/4W
R13 330R Metal film resistor, 1/4W
R14 1k Metal film resistor, 1/4W
R15 1k Metal film resistor, 1/4W
R16 1k Metal film resistor, 1/4W
R17 1k Metal film resistor, 1/4W
R18 100k Metal film resistor, 1/4W
R19 100k Metal film resistor, 1/4W
RPD 2M2 Metal film resistor, 1/4W Input pulldown resistor. Can be as low as 1M.
LEDR 4k7 Metal film resistor, 1/4W LED current-limiting resistor. Adjust value to change LED brightness.
C1 47n Film capacitor, 7.2 x 2.5mm
C2 1uF Film capacitor, 7.2 x 3.5mm
C3 2.2uF Film capacitor, 7.2 x 5mm
C4 330pF MLCC capacitor, NP0/C0G
C5 1uF Film capacitor, 7.2 x 3.5mm
C6 10n Film capacitor, 7.2 x 2.5mm
C7 10uF Electrolytic capacitor, 5mm
C8 33n Film capacitor, 7.2 x 2.5mm
C9 100uF Electrolytic capacitor, 6.3mm Power supply filter capacitor.

LUNA OPTICAL TREMOLO 4
PARTS LIST, CONT.
PART VALUE TYPE NOTES
C10 47uF Electrolytic capacitor, 5mm Reference voltage filter capacitor.
C11 100n MLCC capacitor, X7R Power supply filter capacitor.
D1 1N5817 Schottky diode, DO-41
D2 1N914 Fast-switching diode, DO-35
D3 1N914 Fast-switching diode, DO-35
Q1 2N5457 JFET, general purpose, TO-92 Can sub with a more common BJT transistor. See build notes.
VACT VTL5C3 Photocoupler, fast on/fast off See build notes for more information on photocoupler selection.
IC1 TL072 Operational amplifier, DIP8
IC1-S DIP-8 socket IC socket, DIP-8
IC2 TL022 Operational amplifier, DIP8
IC2-S DIP-8 socket IC socket, DIP-8
DEPTH 1kB 16mm right-angle PCB mount pot
RATE 100kC 16mm right-angle PCB mount pot
SMTH 500kB 16mm right-angle PCB mount pot
SPACE 500kB 16mm right-angle PCB mount pot
SYM 500kB 16mm right-angle PCB mount pot
VOL 50kA 16mm right-angle PCB mount pot
LED 5mm LED, 5mm, red diffused
IN 1/4" stereo 1/4" phone jack, closed frame Switchcraft 112BX or equivalent.
OUT 1/4" mono 1/4" phone jack, closed frame Switchcraft 111X or equivalent.
DC 2.1mm DC jack, 2.1mm panel mount Mouser 163-4302-E or equivalent.
BATT Battery snap 9V battery snap Optional. Use the soft plastic type—the hard-shell type will not fit.
FSW 3PDT Stomp switch, 3PDT
ENC 125B Enclosure, die-cast aluminum Can also use a Hammond 1590N1.

LUNA OPTICAL TREMOLO 5
BUILD NOTES
Vactrol selection
The Luna sounds best with a VTL5C3 workalike. Since the original VTL5C3 is no longer made, you’ll
likely need to find a substitute. Xvive and CoolAudio make their own version under the same part
number, VTL5C3, and both are available from Small Bear Electronics as well as several international
retailers. Alternately, Small Bear Electronics sells the Macron MI1210CLF-R which works just as well.
It’s also possible to make your own photocoupler by using an LED and an LDR. However, this is outside
the scope of this documentation and you’ll have to ask for help on a forum if you’re not sure what to do.
Note: Do not use a low “on” resistance photocoupler such as the NSL-32. The resistance (500 ohms to
1k) is so low that the gain ratio will be thrown off balance in the following gain stage. The volume control
will be unusable, and the combined high-pass filter with C3 will cut the bass significantly at the higher-
volume end of the cycle.
Input buffer
The original Tremulus Lune does not have an input buffer. Since the first op-amp stage is in an inverting
configuration, this means the source impedance directly affects the gain of the effect, and you will have
drastically different behavior if the pedal is connected straight to a guitar vs. coming after a buffer.
The Luna adds an input buffer to counteract this. The default configuration from the parts list & layout is
to use a JFET. However, due to the scarcity of TO-92 JFETs, the buffer can be configured to instead use a
more common NPN bipolar transistor such as a 2N5088 or 2N3094 with only one resistor change.
To use a BJT, omit R2 and use 470k for RX1. Then, insert the transistor as shown below:
Assuming E-B-C pinout, you just shift it to the left by 1 pin from where the JFET would normally go.
JFET selection
The 2N5457 is a great general-purpose JFET, but anything with a high VGS(off) value (also known as VP
or pinch-off voltage) will work well here. Other options include 2N5458, MPF102, PN4303, PN4304,
BF244A, BF245A among many more.

LUNA OPTICAL TREMOLO 6
SCHEMATIC
GND
2M2
1N5817
100uF
GND
+9V
100n
VA
100kC
1kB
500kB
500kB
47k
47k
TL072
100k
100k
GND
47uF
GND
TL072
TL022
TL022
1uF
1M
GND
1k
47n
1M
220k150k
GND
220k
10n
220k
2k7
10uF
GND
330pF
2u2
330R
1k
1k
GND
1k
1k
33n
500kB
50kA
1k
1uF
GND
VA
GND
VA
GND
VA VA
VB
VB
VB
1k
2N5457
VA
GND
OMIT
VB
RPD
D1
C9
IN
OUT
C11
RATE
1
2
3
DEPTH
1
2
3
SPACING
1
2
3
SMOOTH
1
2
3
VACTROL_B
VACTROL_B
R4
R5
IC1A
2
3
1
R18
R19
C10
84
IC1B
6
5
7
IC2A
2
3
1
84
IC2B
6
5
7
C5
R7
R1
C1
R2
R8R9
R10
C6
R11
R12
C7
C4
C3
R13
R14
R15
R16
R17 RATE_LED
D2
D3
C8
1
2
3
SYMMETRY
VOLUME
1
2
3
R3
C2
R6
Q1
RX1
GND
GND

LUNA OPTICAL TREMOLO 7
DRILL TEMPLATE
Cut out this drill template, fold the edges and tape it to the enclosure. Before drilling, it’s recommended
to first use a center punch for each of the holes to help guide the drill bit.
Ensure that this template is printed at 100% or “Actual Size”. You can double-check this by measuring
the scale on the printed page.
Top jack layout requires the use of closed-frame jacks like the Switchcraft 111X. Open-frame jacks will
not fit in layouts with 5 or more knobs due to the placement of the DC jack.
LED hole drill size assumes the use of a 5mm LED bezel, available from several parts suppliers. Adjust
size accordingly if using something different, such as a 3mm bezel, a plastic bezel, or just a plain LED.
0 1 2
CM
0 1
INCH
125B
ø3/8” ø1/2”
0.385”
0.625” 0.625”
ø3/8”
OUT DC IN
x: -0.775, y: +1.71 x: +0.775, y: +1.71
ø9/32” ø9/32”
x: -0.775, y: +0.41
ø9/32”
x: 0, y: +1.71
ø9/32”
x: 0, y: +0.41
ø9/32” x: +0.775, y: +0.41
ø9/32”
x: 0, y: -1.20
ø15/32”
x: -0.775, y: -1.20
ø5/16”
x: +0.775, y: -1.20
ø5/16”
CENTER (0,0)
SYMMETRY SPACING RATE
VOLUME DEPTH SMOOTH
FOOTSWITCHLED
ON/OFF
LED
RATE

LUNA OPTICAL TREMOLO 8
ENCLOSURE LAYOUT
Enclosure is shown without jacks. See next page for jack layout and wiring.
125B

LUNA OPTICAL TREMOLO 9
WIRING DIAGRAM
125B
IN +VGND RATE N.C. OUT
PCB
IN
GND +V +V JACK GND JACK
OUTIN
RATE GND PCB
OUT
Shown with optional 9V battery. If battery is omitted, both jacks can be mono rather than one being stereo.
Leave the far-right lug of the DC jack unconnected.

LUNA OPTICAL TREMOLO 10
LICENSE & USAGE
No direct support is offered for these projects beyond the provided documentation. It’s assumed
that you have at least some experience building pedals before starting one of these. Replacements and
refunds cannot be offered unless it can be shown that the circuit or documentation are in error.
All of these circuits have been tested in good faith in their base configurations. However, not all the
modifications or variations have necessarily been tested. These are offered only as suggestions based
on the experience and opinions of others.
Projects may be used for commercial endeavors in any quantity unless specifically noted. No
attribution is necessary, though a link back is always greatly appreciated. The only usage restrictions
are that (1) you cannot resell the PCB as part of a kit without prior arrangement, and (2) you cannot
“goop” the circuit, scratch off the screenprint, or otherwise obfuscate the circuit to disguise its source.
(In other words: you don’t have to go out of your way to advertise the fact that you use these PCBs, but
please don’t go out of your way to hide it. The guitar effects industry needs more transparency, not less!)
DOCUMENT REVISIONS
1.0.2 (2020-12-07)
Corrected inconsistent value for Volume pot between schematic and parts list (it should be 50kA).
1.0.1 (2020-11-02)
Corrected wiring diagram to show missing wire for Rate LED.
1.0.0 (2019-03-14)
Initial release.